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What does The Fresh Prince of Bel-Air, Morning Glory by Oasis, the sound of a dial-up modem and the SIR3 radar system all have in common? They were all things that helped to make the 1990’s. We asked SUMO Directors Dr. John Gater and Peter Barker to take a trip down memory lane and look back at their 'old' geophysical equipment. After this, we began to see how far geophysics technology has come since. SUMO Geophysics was founded by the merging of SUMO Group members GSB Prospection Limited and Stratascan Limited, both of which were established in the late 80's-early 90's. It's safe to say that since then, members of the merged SUMO Geophysics have seen their fair share of geophysical kit. Peter Barker (originally the founder of Stratascan) has a wealth of geophysical knowledge and still has a stash of his 'old' equipment including the GSSI Subsurface Interface Radar 3 system (SIR 3) which he purchased in 1990.  The SIR 3 was a first generation digital GPR system designed for a broad range of environmental, geotechnical, geological, and engineering applications. When Peter first bought the SIR 3, it ran off a 12-volt battery and was even used in an early Time Team episode by his now colleague, Dr. John Gater. While the SIR 3 is no longer used at SUMO, it provides a good contrast to the current digital systems. When Peter bought it new in 1990, it was state of the art technology! Dr John Gater (the original founder of GSB Prospection) also dug out some images of his earlier geophysics years. The image below shows an electrical imaging survey being completed. This process involved probes being manually inserted into the ground. Following this it would be moved apart manually, once a reading had been logged. He explained how this process could take half a day to survey just a single line. In contrast, this would now take about 10 minutes with modern technology. Above: John Gater completing an electrical imaging survey with the late Arnold Aspinall and Jim Pocock from Bradford University. Above: Dr. John Gater completing a near surface geophysics survey using a magnetometer So, how far has near surface geophysics come? Geophysical technology has greatly improved over the decades. Since the use of equipment such as the SIR 3 systems, SUMO now employs the latest GSSI Duel Frequency Ground Penetrating Radar (GPR) equipment. We even have High-Density GPR survey options with both manual and cart-based kit. The speed of data collection, processing time as well as the quality of the data collected, has all advanced dramatically and 3D outputs mean clients can now get full visibility below the ground with a SUMO GPR Survey. As well as these advantages: Modern equipment is much more lightweight and often only needs a single operator. Data loggers are inbuilt (no more writing down data readings on a clipboard in the rain!). The volume and speed of data collection is vastly improved. The kit is largely weatherproof meaning we can respond no matter the weather conditions. Data analysis on computers can be carried out on site instead of returning to the laboratory to process the data. GPS has also revolutionised our work and provides accurate locational data. There is no need for 30m tapes to set out grids and tie them in to points on OS Maps, as done previously. Geophysical data is now geo-referenced, so it can be accurately laid onto base maps or even Google Images. Above: Example of High Density GPR data collected by SUMO Geophysics Above: Ground Penetrating Radar data in a 3D output So, whilst some of the romantics amongst us may occasionally hanker after the ‘good old days’, the surveyors, in-the-field appreciate the benefits of modern technology and our clients enjoy the improved speed and accuracy of its output: a win / win situation.

3D modelling is the process of creating a three-dimensional computer model which represents a 'real-world' object. It is used in a wide variety of industries. This includes gaming, architecture and product development. There is no surprise that the construction industry has followed in these tech-advancing footsteps and has adopted these developments. The above 3D model, created by SUMO Measured Building, is an example of the various lighting conditions and backgrounds which can be applied to a 3D model. It is these details which help to create the most realistic visualisation of the building in various conditions and locations. What types of modelling do we do at SUMO? There is a range of 3D offerings at SUMO including: Photogrammetry, and SketchUp, Revit and AutoCAD models. Each of which have a range of applications. In our opinion, the focus shouldn't necessarily be on which software you use to create the model. The focus should rather be the eventual use of the model (what will its purpose be?) and how the information is presented to the end client. Why do we recommend 3D models for survey purposes? 3D models are a fantastic method for visualizing and rendering graphic designs. They are rapidly gaining popularity due to the benefits they provide. This includes: greater accuracy, efficiency, and reduced final project costs. With 3D modelling becoming the new 'norm', we are now able to pack 'more' into less. At SUMO we see an ever-growing demand and interest in all things 3D. Our clients have always been willing to take the tech journey with us and enjoy numerous benefits to their projects. So, what are the benefits? Models are easily shareable and can be edited or updated. Experience shows that our 3D models can identify potential problems for client much earlier in a projects timeline. Easily accessible data which can be maintained throughout the life-cycle of a project. What you need to know when commissioning a 3D model? Establish what your models purpose will be. It may seem obvious, but you need to be clear with your surveyor about the usage of the model for example: Is the model for verification? A visualisation for your team or client? For demolition purposes? To aid planning? For design purposes? Being clear about aims such as these can mean vital information is not missed, or expenses unnecessarily incurred. It also means that the model you do eventually commission will have the accuracy that is the most suitable for the job. For example, a model of a site scheduled for demolition, commissioned with ‘all bells and whistles’, might incur huge costs to gain such a high level of detail, but may be entirely inappropriate considering the site is going to be destroyed. In this case, a lower accuracy, cheaper modelling option would be more suited. The above example of a SketchUp 3D model was produced by SUMO as the most suitable option for our client’s individual needs to visualise the property.  SUMO liaised with the client to tailor a 3D deliverable suitable for their needs. All whilst minimising the cost and time taken to complete the model by using the most appropriate software for the job. At SUMO we aim to understand each of our client's individual project needs and to tailor our service accordingly. We pride ourselves on producing high quality 3D models at a competitive price, whilst keeping the client's best interests in mind. We achieve this by using the most appropriate, tailored models to suit their individual site and project needs.

The PAS 128 specification for underground utility detection provides a robust methodology for delivering utility surveys in the UK. Introduced in 2014, it focuses on the levels of accuracy that you can specify when commissioning a PAS 128 compliant underground utility survey. But how does it differ from other survey options and more importantly; is it the best use of your budget? What is PAS 128? PAS 128:2014 is the latest specification for underground utility detection. It differs from other survey options  The purpose of the PAS 128 specification is to set out the accuracy to which survey data is captured. As well as this, the quality expected from the data and the confidence that can be placed in the data will be included. Although, it is not relevant for all utility surveys. Where it is appropriate to specify a PAS 128 survey, there will be benefits for the client, the practitioner and the general public. The specification covers: The project planning and scoping process. The classification system for quality levels based on the survey category type, the location accuracy, the need for post-processing and the level of supporting data. Desktop utility records search. Detection. Verification. Location. Deliverables. PAS 128 provides a strong procedure for delivering utility surveys in the UK. There are four Survey Category Types. These are referred to in the specification and each one focuses on levels of precision specified in an underground utility survey that is PAS 128 compliant. Why was PAS 128 needed? It aimed to combat the inconsistent costs and service levels across the utility survey industry. To highlight inferior data being provided by inexperienced surveyors. Inaccurate data on the existence and location of utility assets can be detrimental to a projects smooth running. A lack of reliable information during the design and construction phases can result in expensive errors. The safety of workers and the public can be put at risk as well as many other needless problems. As a result, it is vital that accurate information for the location of underground utilities is available. Accurate mapping of utility networks helps to improve asset modelling capabilities with more resolute outcomes. The benefits of PAS 128 ensure a high level of accuracy and certainty of the results for each utility detection survey. This increased accuracy and reliability provided to the client enables them to plan effectively for all utility-based activities. Survey quality types We can help answer the question 'are you getting the best use of your budget'. We want to demystify a complex technical area and improve communication between clients and practitioners; it is important to understand the hierarchal approach PAS 128 has to the production of utility surveys. There are four survey quality levels which the client can specify: A through to D. It is written for practitioners to adhere to, with clients specifying the survey they require. Your survey provider should help you in determining the most appropriate intensity with which it is carried out. Above: The 4 quality levels of PAS 128 and their relative cost. Above: PAS 128 Quality Levels of information. Two technical directors at The SUMO Group were appointed to the Drafting Panel and the Steering Group by ICE and BSI to assist with the writing of the PAS 128 specification. This was also part funded by SUMO. The guiding role that SUMO played in the creation process, means that we have an in-depth understanding of how PAS 128 works.  Also, the best and most economical approach to applying PAS 128 certified survey options to your site and budgetary needs. At SUMO we understand that many client’s commissioning a survey are obligated by ‘higher powers’ to specify a PAS 128 compliant survey. However, the relevance of methodologies can be easily misunderstood. We are often (mistakenly, in our opinion) asked for the highest, most costly quality level of PAS 128 survey to be completed throughout a site. It is a common misconception that by asking for the highest-level survey, you will receive the best survey. In fact, in most cases this isn't actually the best approach. Asking for the highest quality level of PAS 128 may be too intensive for your specific site area. But this could also needlessly raise your survey costs. The PAS 128 specification was written to allow for the survey area to be subdivided so that various and appropriate levels of PAS 128 survey can be applied to different areas. Referencing the quality level tables above means that we can satisfy a projects' needs whilst also addressing safety and financial requirements with varying quality levels and relative costs. For example: “I need an M4P PAS 128 survey; because it’s the best” Yes, it is the most intensive PAS 128 survey option. However, it may not be the best solution for your specific site. “Tell me why” Your site is predominantly open greenfield, partly tarmac carpark and may not require the intensive survey grid used in an M4P survey. Conducting an M4P survey throughout this specific site will also take longer to survey and will cost considerably more. In this case, an M1P survey for the greenfield space and an M2P survey for the carpark may be the best solution. It will still be fully PAS 128 compliant and it will also be considerably cheaper than a full M4P survey! So, to answer our question – Are you currently getting the best use of your budget when commissioning a PAS 128 survey or could we help you to do so, whilst saving money? PAS 128 is setting the standards within the survey industry. Survey providers offering PAS 128 compliancy must adhere to these specifications and standards. Having said this, you know that with PAS 128 you're getting the most assured standard of survey for your money. The comparison of quotes should also be much easier, as all compliant quotes should be based on a similar methodology. Having a brief understanding of PAS 128 whilst commissioning your survey will ensure the best chance of maximising your budget. Any quality survey provider which offers PAS 128 compliancy such as SUMO will be able to discuss, agree and scope the survey with you. Unfortunately, in our view, PAS 128 does not provide enough client guidance on commissioning a survey. However, clients have a defined role in the PAS 128 survey process.

The possible application of geophysical techniques is vast. In our experience however, it is generally thought that geophysics is reserved for application to heritage sites or areas containing archaeology only. However, there is a much wider use for these techniques including Civil Engineering, as detailed below. Above: SUMO Geophysics Director Dr John Gater holding a geophysical magnetometer. So, what does 'Geophysics' mean? In their book Revealing the Buried Past; Geophysics for Archaeologists by Chris Gaffney and SUMO Director John Gater, the authors suggest the following: “The examination of the Earth's physical properties using non-invasive ground survey techniques to reveal buried archaeological features, sites and landscapes.” The Oxford English Dictionary simply defines the term Geophysics as “The physics of the earth”, a much simpler explanation! Archaeological geophysics has become a specialist subject in its own right, but nearly all of the techniques used in archaeology have actually been borrowed from geological or exploration geophysics. In some cases, it is only the implementation that has been radically changed. What equipment is used? The types of instruments that are used can be classified in a number of ways. For example, some need to be inserted into the ground, others simply require contact with the ground while some of the instruments are carried above the surface. However, the most important difference between the techniques is whether or not they introduce an external phenomenon or if they measure what is there directly: they are termed 'active' and 'passive' respectively. Above: A list of geophysical techniques used for locating, delimiting and investigating archaeological sites. How can Geophysics be used for Civil Engineering? Just as geophysical techniques can discover hidden Archaeological features, they can also identify a range of features typically found on engineering sites and the process of surveying an engineering site is very similar and often uses the same equipment. Although the techniques in the table above are used widely in Civil Engineering, those techniques in the bottom half are used equally as much as those at the top. This is because the targets are different: Rebar Voids Buried obstructions Clay Pipes Drains Badger setts Metal pipes Cables such as mains electricity or internet cables Remember, any survey provider worth their salt will be able to guide you through the commission of your survey and answer your queries. At SUMO we are dedicated to making sure our clients understand the process from start to finish. Plus, we can even give further assistance with face-to-face presentations to explain your survey data.

Topographic surveys are a must-have for any professional who needs a record of the physical features of their site. Whether its 1000 acres of land or simply your back garden; SUMO’s Senior Surveyor Patrick Cullity talks through the basics of topography. We look into how it can apply to a variety of sites. What is Topography? The Oxford English Dictionary definition of the word topography (often referred to as ‘topo’ within the survey industry) is the arrangement of the natural and artificial physical features of an area. A topographic survey records a mapped representation of the physical features of an area. Typical features that are mapped include: road features, buildings, walls, fences, street furniture, surface utility covers, trees and vegetation (the list is endless). What is the process? Topographic surveys are completed using a total station and topographic pole. The total station is positioned within the survey area. Then the Surveyor records various physical features using a topographic pole. Each of these recordings is referred to as a ‘survey point’. Above left: Topographic total station Right: Topographic pole. Every point surveyed is traced by the total station, which stores the data for post-processing. Each point is surveyed in 3D and the Eastings, Northings and Elevation are recorded. Due to the data being collected in 3D the completed topographic survey can therefore be supplied in a 2D drawing or 3D model. So, is all the equipment the same? There is a great range of equipment available within the topographic survey industry. These are also new technological advances available as well. Typically, for small to medium sized site areas, conventional total stations or GPS receivers are often used. They are the most appropriate equipment for the specific site area and size of the project. Although, on larger sites, digital aerial photogrammetry (UAV) may be used. This can be much cheaper due to the speed of data collection over a larger scale area. As well as this, it cuts the ‘man-hours’ needed to survey sites of a larger scale, reducing costs further. What equipment does SUMO use? All our SUMO surveyors are identically equipped with the latest Trimble Robotic total stations and GPS surveying units, which utilise the VRS network. This is for referencing the surveys to the Ordnance Survey Grid and Level datum. Example Survey drawing: What are the applications of the technique? The applications of the technique are endless. Referring back to the definition of a topographic survey, it is a mapped representation of the physical features of an area. This means that the technique (in theory) applies to any physical site. The limitations of the technique, which would disallow an area to be surveyed conventionally, are that the equipment must be able to function correctly within the space. As well as this, the surveyor must be able to safely survey the area. Even in these instances where a conventional topographic survey is not suitable, there is still the option for the use of Aerial Drones (UAV) to survey those hard to reach areas. What are the benefits of having a Topographic Survey completed? A topographic survey creates a mapped representation of the physical features of an area, which aids visualisation. Topographic models are used extensively in many sectors. This includes planning, design and construction in Civil Engineering projects, environmental projects and many more. In these cases, a full topographic drawing may prove essential to the smooth running of the project. The benefits of commissioning a full topographic survey will be seen throughout the life cycle of the project SUMO prides itself on providing the best quality survey drawings in the industry. They provide fully colour-coded as standard and are available in hard and electronic copy. For more information on Topographic surveys and how SUMO can apply this technique to your project contact us today.

It’s well known within the survey industry that underground mapping surveys completed at the pre-demolition stage of a project yield all-round benefits. However, in our experience many clients don’t understand the importance of the survey work being completed pre-demolition. This can result in demolishing more than just their site, but also the quality of their survey results. A key part of a utility survey is being able to understand the site and its prior use. Knowing the environment that the surveyors will be working in is critical. Whether it’s the project estimating in the office or undertaking the survey itself. The site could be a relatively low-risk greenfield site, or a much higher risk site such as a hospital. But knowing what they will be working with will dramatically improve the quality of the survey deliverable. What are the benefits of a pre-demolition survey? At the pre-demolition stage the site information is only available whilst it has been untouched. Simply by walking the site, a surveyor can use reasonable judgment to build a picture of what is underground. This would be from identifying features such as manhole covers, ground scars and lamp columns. Even identifying frosted glass on buildings (indicating a toilet block) suggests there will be evidence of foul drains in the area. These factors should be considered, as they will be lost after demolition. The benefit of this information is that more detail can be added to the final deliverable. This gives the client a better picture of what’s going on underground and reduces the risks associated with the next stages of construction. Why are people still commissioning surveys post-demolition? Many clients tell us that the cost of a post-demolition survey can be lower than that of a pre-demotion survey. However, it is our experience that these clients are often unaware of the actual reason for this reduction in cost. It is because a post-demolition survey limits what is provided to the client. Unlike a pre-demolition survey where the surveyor can deliver drawings which show a network of pipes and cables with detailed references; it is often the case in a post-demolition survey, that the client will receive a limited drawing containing spurious findings. As well as this, large numbers of unknown buried features can be due to the lack of information obtainable from a post-demolition site. As such, SUMO always encourages clients to have utility survey work completed pre-demolition. This mitigates the significant risk associated with features that haven’t been located. The equipment and working on post-demolition sites: There is a common thought of ‘why do you need to visit my site before demolition, can’t the equipment still find buried features, post demolition?’ Well yes, in theory it can, but only if the remaining ground conditions are suitable. However, the likelihood is that the ground conditions will become severely limited as soon as the demolition has occurred. Thus, increasing the risks associated with the next stages of the project. There are a number of reasons why there could be equipment limitations on a post-demolition site. Including: The equipment may be unusable due to the lack of infrastructure. Manhole chambers may have been buried and lampposts destroyed, so in these circumstances, there would be nothing for the surveyor to clamp Electromagnetic Location equipment to. In these site conditions where the equipment relies on infrastructure being present, the surveyor will be limited to carrying out a much less effective ‘free hand sweep’ with poorer results. The post-demolition ground conditions may have become unsuitable for many types of survey equipment. This could the use of Ground Probing Radar (GPR). This is is essential for finding non-metallic pipes and cables. They require a smooth and flat surface to produce optimal results, limiting the survey further. So, what are you risking by getting your survey completed post-demolition? It is likely that planned demolition sites are going to be re-developed. Therefore, the ground opened up during later building processes. By taking unnecessary risks to save on initial survey costs, you may end up spending considerably more over the course of the project. This could mean potential fines from hitting buried utilities. Other risks also include: Personal injury - this could range from minor to fatal incidents. Consequential loss claims due to downtime. Reputational damages. So ask yourself, are you willing to take the risk? If not call SUMO now for a free quote without commitment.

Geophysical techniques can be applied to a wide variety of sites to investigate numerous types of materials and structures below the ground. We’ve put together this list of features that can be found by geophysical survey techniques. 1: Air Voids and Cavities Buried vaults, crypts, culverts, sewers and heating ducts are just a few examples of where voiding can occur. Voiding caused by burials and crypts can be identified within current or former ecclesiastical sites using an archaeological survey. Other indicators of voids are swallow holes and subsidence, which can be found in many locations such as greenfield sites, roads and brownfield sites. Typically, near surface geophysics techniques such as Ground Penetrating Radar, Ground Conductivity and Microgravity can  be used to find these features. 2: Buried Mineshafts The approximate locations of old mine shafts and adits are recorded on historic maps and records. Some may have been capped and others not recorded at all will be difficult to find. A geophysical survey can be the most cost-effective method of locating them before development work commences. Buried mine shafts are interesting in that a range of geophysics techniques can be used to characterise the buried features. Initially we’d recommend to a client the use of Ground Penetrating Radar and Ground Conductivity. The use of magnetometry can be used to find the remains of any metal structures associated with the pithead gear. Above: Example Radargram showing the location of a buried mineshaft. 3: Buried Fuel and Attenuation Tanks The discovery of buried fuel and attenuation tanks can create health, safety and environmental concerns. As well as this, there can be significant cost implications. The identification of buried tanks and their location is therefore essential at the design stage and may be of particular relevance to the redevelopment of brownfield sites. Buried fuel tanks should be easily identified using Ground Penetrating Radar, Ground conductivity or Magnetometry survey techniques. Above: The image shows buried attenuation tanks. Above: Radargram showing the location of buried attenuation tanks. Above: This example of Ground Penetrating Radar data shows the location of buried attenuation tanks. 4: Air Raid Shelters Throughout the UK thousands of air raid shelters were constructed during World War II. These varied from large public shelters built with bricks andreinforced concrete through to small private shelters using corrugated steel panels. Many of these were removed after the war, however, others remain buried and are often encountered during construction works. Ground Penetrating Radar, Ground Conductivity and possibly Electrical Resistance Tomography ERT would be the techniques we would use for identifying air raid shelters. Above: This image shows the structure of a typical Air Raid Shelter that would have been used during the war. Above: This example of Radar data shows the location of buried Air Raid Shelters. 5: Land Forms and Geomorphology Before construction and infrastructure projects start, it often proves necessary to characterise landscape features to assess their suitability for design purposes. This could include attributes such as depth of drift cover to bedrock, body of water profiling and sediment thickness, or the extent of sink hole formation. Ground conductivity and ERT has the ability to find Palaeochannels and near surface rock outcrops. The depth of rockhead can be mapped through the use of GPR. Lastly, Magnetic surveys can be used to detect igneous intrusions. Above: Example of Seismic Refraction data. This cross-section of data shows the depth of conglomerate and limestone. Above: Example of Seismic Refraction data. This Plan View of the site shows the depth to the Bedrock. 6: Waterfronts Significant areas of voiding can be created where water under pressure has forced its way through masonry and brick linings. Typically, we would find this sort of voiding in harbour walls and quays by using Ground Penetration Radar. 7: Badger Setts As a protected species, it is important to identify the existence and extent of any badger setts before commencing construction work. Often having deep and intricate tunnels, badger sets can be best discovered using Ground Penetrating Radar. 8: Rebar Rebar can successfully be located by Ground Penetrating Radar and Cover Meters. It is often a survey technique we pursue when our clients have plans for drilling but are unable to obtain previous records of the rebar’s location. Above: SUMO Geophysics can utilise a palm antenna to locate rebar. It is the ideal piece of equipment to locate features such as rebar and tension cables. Above: Example of Ground Penetrating Radar Radargram showing the location of rebar. 9: Hidden Flues and Chimneys Identifying building features such as these would be best suited to High-Frequency Structural Radar. This technique can also find similar embedded features and voiding caused by crumbling masonry and water ingress. Above: This example of radar data shows the location of a former fireplace. SUMO Geophysics has over 30 years’ experience within the archaeological & geophysics survey industry and unrivalled knowledge. Contact us today with your quires and we would be happy to give you further information about the use of geophysical techniques.

In an industry that is constantly evolving and looking towards the newest methods of working, it can come as a surprise that although there is a will to move forward there isn’t always the way. SUMO’s Tony Rogers explains why although we are seeing an increasing shift towards full 3D outputs, we are regularly asked for traditional 2D deliverables. Above: 2D plans and elevations at St Albans Cathedral created by APR Services So, Tony, what is your initial reaction to the continued work in 2D as opposed to shifting fully to 3D? In our experience, our clients tell us that the use of 3D is generally only beneficial at the design stage of a project. Design professionals such as architects will often benefit by working in 3D. Although, most other trades within the building process continue to work in 2D. So with this mixture of client needs, I am not sure there will ever be a full shift to 3D. In fact, 2D drawings are actually required throughout the entire build process by many trade professionals. Although it is possible to extract basic 2D drawings from 3D models, this process tends to need further manipulation. The use of 3D can be inappropriate for many projects and environments due to the following factors: 3D costs more to work with. It often requires a higher level of skill and more expensive equipment to interpret. Creating work in 3D can generate an unnecessary level of detail. Meaning that you have a very complex and data hungry data set which is not needed. You mentioned that 3D can be inappropriate for certain projects and environments. Can you tell us more? Yes, the obvious area where this point is most true is Heritage work. Usually in Heritage projects, features aren’t square or regular. We find that everything is individual and needs to be drawn independently. Modelling in 3D to this level of detail for such projects is difficult as well as having the potential to be very expensive. That said, we can still capture the intricate details via 3D laser scanning. Then we generate the 2D output as discussed further below. An example of a project such as this is St Albans Cathedral. APR Services (now part of the SUMO Group) have been surveying this site in stages for the last 15 years. The initial data captured using 3D laser scanning. We then used the scan data to provide detailed plans and elevations (often down to individual bricks) in 2D to meet the needs of the Conservation Architects. Above: A section of the 2D survey deliverable from St Albans Cathedral. Above: This photograph of the St Albans Cathedral shows the external appearance of the building. In the final survey drawing, the bricks have been individually drawn for the highest-degree of accuracy. The walls of St Albans Cathedral are not straight. As well as this, other features are irregular and the floors are not level. 3D models would not be appropriate or useful as there too many irregularities within the building. This is generally expected from a building of this age. So, what are the main challenges with 3D modelling Heritage sites? 3D software, such as Revit, is designed for creating new buildings and structures from scratch in a virtual environment. Whereas the sites that SUMO survey exist within the ‘real world’ and have to be portrayed in a CAD environment. 3D software (often ideal for the design stages) lacks the tools to measure the level of irregularity found on heritage structures. What deliverables do SUMO generally produce as requested by clients? In recent years, the wider use of Laser Scanners allows surveyors to capture everything easily in 3D in one mobilisation. This cuts the need for more visits to capture extra data. It also gives us the option to offer clients this data as a 2D and/or 3D deliverable. We can capture the finest details as a ‘cloud of points’ using the laser scanner. However, converting this point cloud data to 3D solid objects is not an easy task. This is because Meshes used during the modelling process are very heavy to manipulate. As well as this direct modelling is complex and time-consuming. Often we create 2D drawings or what we call ‘ortho images’ of complex features as this is all that is required for the work to carry on. We can also provide the point cloud for clients to then model from themselves. This is becoming more common as clients can decide the tolerance they will model to, rather than the surveyor. In addition, whilst 3D views make it easy to see how something looks, you cannot physically measure or manipulate them without specialist tools. Can you give us a summary of why surveyors are still experiencing larger volumes of 2D requests? The majority of clients request 2D drawings as they are still working or designing in 2D. This is often the case, particularly on the smaller projects. It is a slow transition to 3D. I believe advances in the software are still needed before it is going to become the ‘norm’. There is a need for skill advancements, as it’s not an easy task for many of the people using the information to be able to manipulate 3D models. We have been using 2D drawings for many centuries. So it is not surprising that it will be a while yet before we are all willing and able to give up the medium.

The SUMO Survey is an adaptable utility survey designed to meet the needs of a wide range of clients looking to minimise the risk of service strikes. With years of experience in providing the SUMO Survey to clients, we discuss the question; can SUMO locate all underground utilities? Addressing the question directly, yes in theory SUMO can locate all underground utilities, however, there are always limitations. Having developed a proven methodology over many years, there are various survey techniques which make up a SUMO Survey. A combination of techniques applied in a systematic manner, such as manhole-cover lifting, electromagnetics (in both passive and active mode), Ground Penetrating Radar (GPR) and statutory plan analysis help to make up our advanced methodology. We can use each survey technique’s strengths to our advantage. This way we have the best chance for the detection of buried utilities no matter their material type. Why does SUMO use different utility survey techniques on a site, wouldn’t it be better to just choose the most suitable one? With a vast range of applications and differing site conditions, it is not always as simple as a ‘one survey fits all’ approach. Plus, with the use of lots of survey techniques, you can gain the optimum ‘picture’ of what’s beneath the ground. Try and think of it like having multiple perspectives on something. The more perspective you can get, the better ‘picture’ or understanding you can get. There are also certain limitations to each individual survey technique when used in isolation. This is the very reason why SUMO’s utility survey offers a combined approach in order to have the best possible chance of locating all utilities. What are the limitations of each individual survey technique? The SUMO Survey involves 4 key elements including: Manhole-cover Lifting, Electromagnetics, Ground Penetrating Radar (GPR) and statutory plan collation. Below we will discuss them as individual survey techniques. Whilst highlighting their limitations when used in isolation. Manhole-cover lifting Lifting a manhole cover can give a surveyor 100% visual confirmation of the location and depth of buried utilities within the confines of a manhole. But the restrictions to this survey technique are that the cover could be full of water or debris. This means it could even be sealed shut or covered by an obstruction, therefore stopping the surveyor from using this technique. Also, this technique only allows for the confirmation of utilities within the confines of the manhole itself. So as soon as the utility is outside of the surveyor’s visual reach it is mapped using alternative survey techniques. Once out of the surveyor’s sight, the pipe could change material, taper or change depth. For this reason, we use alternative survey processes to confirm the location of utilities once they are outside the confines of the manhole. In the instance where assessing manhole covers is not achievable, SUMO would use alternative survey techniques to determine the depth and location of buried utilities. The diagram below illustrated manhole-cover lifting. Above: Diagram demonstrating how a surveyor can lift a manhole covers to verify the location of utilities within the confines of the manhole. In this instance, the manhole is free of limitations such as water and debris. This means that the surveyor can confirm and measure the depth to the utilities. Above: Diagram showing the inside of a manhole. This example shows the inside of a manhole. The green fluid in this image is Drain Trace, a coloured fluid used to trace the location of pipes. Electromagnetics (in active and passive mode) In passive mode, the Electromagnetic Locator (EML) can detect cables which emit a power or radio signals. It does this by detecting the magnetic field emitted by the pipe or cable, but it does not detect the utility itself. In passive mode, the surveyor will walk the site with EML and will mark on the ground where a signal is then located. A good way to explain the use of EML used in passive mode is using the example of a street light. At night the street light will turn on, meaning the cable to it is powered up. It will then emit a magnetic field detected using EML. During the daytime, the street light will not be supplied with power. This means there will be no magnetic field emitted and the cable cannot be detected in passive mode. In active mode, SUMO introduces a known frequency into the pipe or cable which can be traced. We create a magnetic field by clamping onto the metallic pipe or cable (i.e. anything that can carry a current) and inducing a current which is then carried through the service and traced from above ground. Introducing a known frequency to the utilities is only achievable where there are metallic pipes or cables exposed. Exposed pipes are usually found through an opened chamber or during excavation. Duct and drainage can be mapped using a tracer wire which is a length of copper wire sheathed in nylon, known as a sonde. The sonde is threaded into a duct or drain and traced from the surface but, any blockages along the pipe route would limit our findings. What’s more, where utilities are in close proximity to each other, cross induction may occur. This is where the signal can ‘jump’ from one cable to another due to their proximity. An example of cross induction is a communications cable which runs next to a power cable. The signal emitted by the power cable could transfer to the communications cable. This causes a false reading on the communications cable. The communications cable would then be detected by the equipment, but, it would have to be labelled with caution as it has been detected as emitting a power signal; even though it may have previously been visually identified as a communications cable by the surveyor lifting a manhole-cover.  Where this occurs we would highlight an ‘area of concern’ as there are multiple cables in one area which cannot be identified.
Ground Penetrating Radar (GPR) Above: This photo shows the High-Density Ground Penetrating Radar equipment that SUMO utilises. GPR has the ability to detect any pipe or cable regardless of the material. This is where we have the best chance of locating plastic and fibre optic cables. It works by emitting a pulse of energy into the ground. It travels through the subsurface until it hits something anomalous to the norm. At which point some of the energy reflects back to the receiving antenna. The time that it takes for the signal to travel back to the receiving antenna is measured and this can be converted into depth estimates. Where these anomalies appear consecutively in adjacent radar traverses it is interpreted as a linear feature (which suggest a pipe, duct or cable). GPR, like any other detection device, has its limitations. Unfortunately, these are due to the law of physics and are out of the surveyor’s control. The GPR unit needs to be operated on relatively flat ground as the antenna (the section of the equipment which emits and receives the radar signal) must be also kept flat on the ground. It needs to allow enough ground coupling for the signal to penetrate the earth and return. If the ground is uneven, the signal will dissipate before it has a chance to enter the ground. In turn, this causes a weak signal to be emitted into the ground. This makes a somewhat accurate detection of the depth of features unachievable.  Where an area of land is too uneven or overgrown, we would not be able to detect plastic and fibre optic cables, so there would be limitations in this area. GPR antennas come in a variety of frequencies. High-frequency antennas will detect anomalies of a few centimetres but will have a very poor depth of penetration. For example, a 1GHz antenna can penetrate to shallow depths of approximately 0.5m and will be able to detect individual rebars within concrete. Whereas a low-frequency 200MHz antenna may penetrate to 3m+. But it will only detect larger items and it is because of this, it is not suitable for locating all services. A mid-range frequency is generally employed for a utility survey and this usually penetrates the ground to around 2-2.5m depth. But, this is affected by the ground conditions. For instance, dry sand is a very good medium for radar signals (a typical depth of 2.5m or upwards may be achieved). In contrast, very dense clay is a poor medium (a typical depth of 1.0m may work), as the clay absorbs the radar signal. Depth estimates are generally very good i.e. +/- 10% accurate. As a rule of thumb, the GPR will only detect anomalies which have a diameter which is 10% of their depth. This means that a 100mm diameter service will be detected at 1m, but it may not be at 1.5m. Therefore, one of the most difficult things to locate is plastic domestic gas service which are very small, but often at a depth of over 0.8m and therefore unable to detect. In this scenario, we would note an ‘assumed route’ on the drawing. The final limitation of GPR is that it can prove difficult to pre-determine how the site may affect the penetration of the signal. As ground conditions can differ over several metres as well as changing throughout the course of the site visit. The GPR system that SUMO utilises is self-calibrating and uses a multi-frequency antenna. Over many years of experience, we trust this achieves the best results irrespective of the ground conditions. Statutory plan collation If available, we will utilise statutory plans. These plans can help us to gain a better understanding of the existing infrastructure. It often gives information on the presence of the following features: Telecommunications Fibre Optics Gas Pipelines Water Mains Sewers Electric cables There are unfortunately restrictions, as the accuracy of these plans can often vary between utility providers. We sometimes find that the plans supplied to SUMO are very accurate. They may even supply us with information such as material type, pipe diameter and other useful measurements. But, we also often encounter statutory plans which will lack information. For example, we may only be given a general area where the utility could be located and what type of utility it is, proving somewhat insufficient for our needs. In an urban context, we find the accuracy of plotted utilities is generally within 2-4m. But in a rural context, it can be 40-60m out. Despite the varying accuracies of the plans, SUMO uses most of these resources where possible. Plans can often help the surveyor to label a buried utility marked as an “unknown” pipe or cable and can act as a checklist of information. Statutory plans allow the surveyor to re-confirm that the survey work is as accurate as possible. For example, if the surveyor believes they have located all the pipes and cables within the survey area but the statutory plans show that there may have been one missed, it allows the surveyor to double-check their working. If after re-confirming their work on site and still being unable to locate a utility which is present on the statutory plan, they can inform the client that there is a possibility that a pipe or cable in the area has gone undetected. In the situation where the location of a utility is not possible, but it is shown on a plan, we would mark the route as “assumed” on the ground or drawing to warn the client of its presence. This further highlights the technique’s limitations that clients must remember that statutory plans are not always accurate. It could, in fact, be the plans which are in error and not that the surveyor has been unable to detect all the utilities. So, by combining individual survey techniques SUMO can locate all underground utilities? In theory, yes! SUMO has developed a proven methodology which combines the benefits of many survey processes to produce the best quality and most accurate survey data. Having more options available means that there is a greater chance of achieving the most accurate data. It also allows SUMO’s utility surveys to be very adaptable. If one technique is unsuitable for a site due to its limitations, then we have an array of alternatives to work around this. However, there are always limitations. On some sites, every technique will work well. On others, we find there are plastic cables at depth, uneven ground, clay geology, blocked manhole etc. Which all affect the outcome of the survey. As well as our combined survey offer, we always ask that the client gives us as much information as possible about the site conditions. This gives us the best chance of locating all utilities by applying the right tools for the job. SUMO has also invested a lot in the training of surveyors to make them multi-disciplined. This allows for further efficiencies and associated cost savings due to a reduction in the workforce needed to survey the site. With years of experience in providing utility services to countless clients, we highly recommend the SUMO Survey approach to any professional who is looking to reduce the risk of service strikes.

In today’s industry, survey equipment theft is a growing problem. With technological advancements forging the way for more adaptable, specialist kit; this has also come with a price tag that appeals to wandering hands. We asked SUMO’s Topographic Director Paul Williams some key questions regarding equipment theft and its impact upon survey companies. Paul, what are your general thoughts on equipment theft? It is a real issue that we see occurring time and time again. In my opinion, there is a general lack of education regarding the worth of surveying equipment as well as a lack of seriousness attached to the crime. This has the knock-on effect that the chances of recovering the instruments are reduced, due to slower response times. In my opinion, this is completely inadequate when you consider that stolen equipment is quickly moved around from place-to-place and often shipped abroad. In addition, most reports are classed as ‘thefts’, when in my experience they could arguably be classified as aggravated robberies. Because of this, cases are often closed due to a lack of further evidence. Are you noticing an increase in equipment theft? Like anything, there are peaks and troughs. Although not definitive, there was a lull in reports of equipment theft over the recent summer, that I saw on social media and in the news in general. I even spoke to a representative at Korec, who expressed that they too had noticed the summer decline in incidents. We had hoped that this decrease was a result of the increased publicity of Locate to Protect (L2p) and other manufacturers attempts to install theft recovery and location tracker equipment. However, this period of decreased incidents quickly changed as I personally saw recent online reports of more than 6 equipment thefts of both Laser Scanners and Total Stations within a very close period. What’s more, SUMO fell victim to this foul play when we had a Trimble S6 Total Station stolen around the same time. So, it seems at the moment as though there is an increase in theft, however, until there are adequate police resources available, we are quite literally on our own in most circumstances. Do these equipment thefts occur in certain parts of the country or are they ‘at random’? In my experience, most thefts occur around the London area which makes sense, as there is a lot of ongoing construction. The Survey Association (TSA) produce a bi-monthly bulletin detailing equipment theft across the UK and this information is very useful to reference as a surveyor. Are the crimes organised? I believe that most survey equipment thefts are organised, in that there are often multiple thieves and in my experience, these are a group of 3 or more individuals. Furthermore, there are suspected crime groups dedicated to the theft of survey equipment. We were fortunate enough to recover a previously stolen Total Station and through the involvement of PANIU (The Police and Agriculture National Intelligence Unit formed in 2008 to help tackle the growth in stolen plant and agricultural equipment), it was believed there was an entire network organising theft across the UK. What impact does equipment theft have upon individual survey companies, as well as on the industry as a whole? It has a varying impact on a company dependent upon their size, but it certainly has a huge financial impact for any business. It is also extremely inconvenient as it results in delays to the daily running of the scheduling, operations and despite our best efforts, it can sometimes affect our clients due to the time delays created. For smaller survey companies that may, for example, have just one instrument, I would expect they impact from the same daily running and operational issues. However, they may have the additional loss of their entire day’s data, which too has huge ramifications. I have also seen evidence where companies have included additional costs to their quotes to accommodate for a security guard. However, I have also seen these quotes not being favoured by their clients because the totalled costs are much higher with the addition of security. What’s more, there will always be surveyors willing to complete the same project at a more competitive rate without the addition of security, hoping that they won’t fall foul to thieves. This cycle can have an impact on a company before they have even got to site as they have either been unsuccessful in winning the project (potentially having financial implications) or are taking extra risks in order to complete the work. Aside from the impact on the companies, I think it’s important to remember that equipment theft has a huge influence on the member of staff who, let’s not forget, has been subjected to a robbery (which can vary in aggression). What more can be done to prevent survey equipment theft? Well, that is the ‘million dollar’ question! Dare I say it, but more Police and a better understanding of the specialist nature of survey equipment is needed. Equipment manufacturers have also introduced theft control measures such as kill switches and more. Plus, there are various other safety measures including lanyards to attach equipment to solid features such as nearby lampposts. However, it’s my experience that nothing will stop a determined group of thieves. This is especially true as there is currently little response at the time of the incident. Eventually, the word will get around to these criminals that the kit can be tracked and traced but until then, it’s a case of highway robbery. What are your thoughts on the impact of equipment theft? Leave a comment in the section below.

SUMO Aerial-Cam’s Adam Stanford has gained expertise over a career spanning more than 30 years. As a leading pilot within the industry, his involvement has been vital in many well-known archaeological projects across the globe. This includes Adam’s long-standing participation in the Stonehenge Riverside Projects. We took some time to ask Adam about his participation in the projects so far... So, Adam what has your involvement been with the Stonehenge projects so far? It all started back in 2006 when I founded Aerial-Cam. After many years working as a field archaeologist I wanted to specialise in archaeological photography, more specifically in on-site aerial work. Back then, aerial solutions were particularly limited, and I started out by using a large 21m telescopic mast that I mounted on my Land Rover! This proved to be a very good method for recording excavations from a height. As well as this, the use of my mast was much more versatile than traditional methods which involved the use of scaffolding towers and wobbly ladders. The first involvement I had, came when I was asked to try out the Aerial-Cam equipment that I had at the time on a research excavation called the Stonehenge Riverside Project. The results I gained proved the be invaluable to the project and following this, my ongoing participation in the project began. Later, I was asked to return to the site each season for excavations around the Durrington Walls, the Cursus, Stonehenge and the Avenue. This is how we ended up discovering the site that is now known as Bluestonehenge. Bluestonehenge is a site in Wales from which large stones were taken and erected by the river Avon. What’s more, we now know that these stones eventually made their way to Stonehenge as well. The subsequent discovery of Bluestonehenge set the scene for further investigations into the origin of the bluestones, and this saw the birth of the Stones of Stonehenge Projects. Aerial-Cam now undertakes annual visits to Pembrokeshire to complete surveys and excavations. What equipment are you currently using to complete the project and has this changed over the years because of technological advancements? Equipment and techniques have evolved substantially over the last twelve years. The Stonehenge projects have been a fantastic opportunity to try out this new equipment and perfect new techniques so that they can be applied to other projects, commercial and academic alike. Over the course of the project, we have used all manner of methods to position cameras where we have needed them. These methods include attaching cameras onto vehicle mounted masts, handheld telescopic masts, poles, kites and even manned aircraft. In the last in five years or so, we have also attached cameras to a range of different UAV’s and Drones. The biggest change I have seen over the last twelve years, is how the imagery that the cameras capture is used to benefit a project. When I started out, it used to be about getting evidence or record photographs of the site from a certain perspective. But, nowadays we take a lot of general photos across the site and use these to create 3D data using the latest Photogrammetry software and powerful computers. You could say (in some cases) that the images captured by our cameras have become part of the process as opposed to the deliverable themselves. The 3D models, digital elevation models and orthomosaic outputs that we can now generate provide a fantastic resource for site recording, analysis and interpretation. They allow for the analysis of earthworks and changes in the state of vegetation in ways we couldn’t do before. This allows for an understanding of the potential and nature of archaeology. This stands even when it’s not visible on the surface of a landscape. Have there been any challenges along the way or new things you’ve had to adapt to? In terms of the project itself, all long running archaeology projects tend to suffer from funding challenges from time to time. However, the crossover from the academic sector into the commercial sector has helped funding considerably. The biggest challenge from a wellbeing and equipment perspective is always the weather. I have experienced all sorts of challenging conditions which make working with the Aerial equipment difficult at times. As well as this, I usually return from south-west Wales rather soggy and windswept. Your work has been instrumental in finding new sites in the Pembrokeshire area. Can you tell us what new discoveries you have made and how you go about uncovering new sites using Aerial-Cam’s equipment? The aerial photogrammetry surveys we undertake are a very good way of understanding the landscape in a study area and they can also highlight previously unknown monuments. The photogrammetry data is similar to Lidar however, photogrammetry is much more targeted and at a greater resolution. On the Stones of Stonehenge Projects, we have found many sites using aerial survey methods. These sites include Bronze Age barrows, ring ditches, a ring cairn, an Iron Age settlement, a Roman Villa and a Medieval burial mound with slate lined graves. These discoveries were not necessarily the archaeology we were looking for, but they are still fantastic finds none the less. What has being part of such important projects been like for you and what have you taken away from them? So far, it has been an incredible journey being a part of these projects and it’s not over yet. I can take away from this experience the knowledge that I have helped to accumulate a huge amount of information, survey results and an enormous archive of images from both the Stonehenge and Pembrokeshire monuments. What’s more, the journey has also created what will be lifelong friendships from the kind of camaraderie I experienced during my time in the forces many years beforehand. All those involved in the projects are working on increasing an understanding and discovering the answers to what Stonehenge was all about. As well as helping to answer questions about why the Neolithic people of five thousand years ago brought together such an extraordinary monument as Stonehenge. There is still a lot more to do yet and I look forward to my continued involvement. What’s the next big adventure for you? Through the Stonehenge projects, I have been fortunate enough to be asked to work on other research projects across the globe. Other projects I have been a part of include the Rapa Nui Landscapes of Construction Project where I ended up doing five trips to Easter Island in the south Pacific. As well this, I have been a part of pilot projects in various destinations such as Qatar and Tunisia, which have all been amazing experiences. My next adventure keeps me on home turf, as we survey some exciting projects throughout Great Britain at a variety of sites such as Castles, Hillforts, lovely country churches and fascinating fields of earthworks.

Photogrammetric Surveys enable rapid data capture using specialist cameras, either fitted to Unmanned Aerial Vehicles (UAV), or attached to tripods and masts. Photogrammetry as a methodology is as old as modern photography and whilst its use declined with the development of laser scanning, in recent years with the rising popularity of UAV's and improvements in associated software, photogrammetry has ‘taken off again’. Overlapping digital images are recorded, which allow the collected survey data to be combined. Modern photogrammetry software can analyse oblique (both horizontal and vertical) and convergent images, as well as parallel images. The current software even permits the use of oblique images from flights that circle the subject, rather than flying in the more typical overlapping swaths used for aerial mapping. SUMO uses the latest technology including UAV’s and mobile masts to survey areas which may be impractical or costly to survey with conventional technology. The advantages of aerial surveys include reduced costs, increased reaction time and best value solutions when combined with the flexibility of conventional methods. It's important when providing Aerial Surveys to have skilled and qualified staff, as well as the necessary licenses and permissions to undertake such surveys. Our pilots are fully qualified to fly UAV's and all flights carried out by SUMO will be conducted within the CAA framework with appropriate risk assessments carried out. ATC (Air Traffic Control) clearances will also be obtained where required and this also extends to liaising with the local police. SUMO’s photogrammetric and aerial services include environmental, conservation and heritage surveys, commercial, industrial and structural inspection. All of these have outputs including photography, photogrammetry and video as well as Pointclouds and meshes. Typical applications of the type of the work that SUMO conducts include: Historic Building Recording - A photogrammetric survey of historic structures, producing 3D models, elevation orthophotographs (rectified photography) and 2D stone by stone detailed line drawings. Roof Inspection - Photographic, photogrammetric and/or video inspections of roofs and inaccessible areas of structures. This eliminates the extra costs associated with scaffolding as well as the risks to personnel working at height. Topographic Survey - Digital terrain models, digital surface models orthorectified (orthophotos) and mapping of large areas. Broadcast Quality Filming - Video production with amazing birds-eye views. Stripped Area Survey - Rapidly records the detail of features of large areas in photo-textured mapping. Above: The example above shows a 3D model created using photogrammetry data collected by SUMO Aerial-Cam. The widespread use of laser scanning for surveying the built environment has made a significant step in surveying those otherwise hard to reach areas. Yet there are still areas that remain inaccessible without the use of costly scaffolding and elevating work platforms. These include confined roofs and high buildings, as well as large landscapes where photogrammetry would be an appropriate and cost-effective solution. In fact, combining Aerial and Laser scanning technologies can often be the best solution. Below is an example of a combined survey approach at the Hampstead Parish Church. Terrestrial 3D laser scanning was initially undertaken at Hampstead Parish Church to quickly capture the elevations of the church.  However due to the building design and the lay of the land, the roof was almost completely obscured and to overcome this, a drone was operated from the ground using separate flights for each side of the church, in order to keep the drone in sight. To match the dataset from the drone to the dataset from the terrestrial laser scanner, it was essential to get good coverage of the site and in order to register the aerial drone data, numerous common points between the terrestrial and aerial drone data were picked. The drone data was then converted to a pointcloud and combined with the scan data to get the comprehensive data set required to create the drawings for the client. Above: Deliverables - A land survey, detailed roof plan and 2D elevations of the church were provided to the church. Photogrammetry is also often used for detailed historic recording to create ortho-images and textured meshes, where the quality and the true colours can provide conservation specialists with extra information that is hard to achieve from other techniques, such as laser scanning alone. Above: An example of Aerial photography taken at Rochester Cathedral using Aerial drones. To summarise, Photogrammetry is very much a developing method of surveying and capturing information thanks to massive advances in both the hardware and software involved. It is also fuelled by the rise in popularity and availability of drones, both for commercial and private use. Whilst working with the latest technology, at SUMO we are keenly waiting to see and embrace the next generation of photogrammetric solutions that are no doubt waiting in the wings for this very modern surveying technique.