Thirty-four years ago, I began my career as a site engineer standing in the mud of Ireland’s utility trenches. Let’s face it, it is always muddy onsite in Ireland! The Irish have a saying, “It only rains twice a week here; once for four days and then for three.” The pipelines I laid back then were never as-built, survey located, or even photographed. As of this writing, I’d bet there is no accurate utility plan depicting a geo-referenced location of any pipelines
that my team and I installed. Sadly, there are millions of miles of other buried services around the world backfilled in this same manner, with no “As-Builts” to help future generations of utility locating professionals.
Creating accurate “As-Built” plans of new utility installations is always a top agenda item with Underground Utility Damage Prevention communities. It is a costly and challenging task to capture accurate subsurface utility data once a system has been backfilled and forgotten. Whether a new utility installation in a greenfield site or a reconstruction of aging infrastructure in urban areas, updating and maintenance of accurate plans for underground utilities is a constant challenge. While many major projects require contractors to survey locate new facility installations, small and medium size constructors
typically don’t have a contract to hire a land surveyor to make periodic site visits. This periodic survey is required to capture precise coordinates and elevations; data that is needed to create an accurate “As -Built” plan.
Therein lies the problem. If a utility contractor isn’t required or paid to survey locate new utility lines, how can the underground asset owner’s Geographic Information System (GIS) get updated to reflect the new installation? Moreover, many asset owners don’t have a GIS work flow that can incorporate data such as ambiguous photographs, swing-tie measurements, handwritten notes, field sketches or low-grade survey coordinates
captured by a site contractor. In fact, most asset owners can’t accept new GIS utility data unless it is captured by a land survey or GIS professional.
As a result, it is not uncommon to have to employ a contract locator to locate even recently installed non-traceable underground utility lines, with little to no ongoing site documentation. If a survey was completed during the installation work, the task of locating and mapping the new line would be a simple process. And, greater protection from
incident and liability would be in place, with the parallel benefit of better, more accessible asset documentation for the owner.
It is in the best interest of every utility contractor to survey and capture the conditions and position of a newly-installed facility daily. This will help with documentation and payment schedules for completed work activities, as well as to build a repository of data in their own commercial territory.
After all, proof of work completion in accordance with project specifications is mutually beneficial to the contactor, site engineer and project owner. Documented data could include the depth of cover, piping details, manhole and vault construction, and valve placements.
But what if there was a cost-effective and highly reliable way for a contractor to capture the position, spatial details and image of a newly built line? What if a contractor could purchase, or lease, a handheld 3D laser system that could quickly survey the trench before backfilling and have the data stored and uploaded to a laptop in the site trailer or work truck? Or what if you could equip each locate team with an accurate sensor and photo scanner to rapidly capture surface marking and other details which could be placed into
larger 3D site models?
If such a system existed, would it not be a gamechanger for all parties in the utility construction industry? The fact is, it does exist and has been in use on construction sites
for several years. LiDAR (Light Detection and Ranging) is a mature technology which has existed for decades. Land surveyors and geospatial professionals use terrestrial LiDAR for topographic and 3D mapping of jobsites. Airborne LiDAR is deployed on drones and aircraft for aboveground asset inventory surveys and structure inspectional and security programs. Image and sensor-based 3D capture is used for aboveground piping design and retrofit planning, often within dedicated CAD software suites or “plug-ins” to capitalize on
efficiency, clash avoidance and ensure design compliance. Captured data file sets are efficient and compressed so field and laptop operations can happen in real time or with quick and inexpensive USB and memory card transfers.
Today, LiDAR and 3D imaging systems have benefited from rapid advancements in hardware, software and production costs. Thanks to research and product developments in areas where LiDAR is used, from autonomous vehicle sensor development to seabed mapping algorithms, we are now more than ever capable of capturing reliable 3D data from a utility
trench or underground utility chamber.
The “As Built” Solution: Manhole and Underground Digital Documentation (MUDD ) Technology
While traditional survey-grade terrestrial laser systems require highly skilled land surveyors to operate and register LiDAR survey point clouds, new Simultaneous Locating and Mapping (SLAM) algorithms have enabled the auto or continuous registration
of point cloud and 3D imaging systems. Static, or tripod, scanners require expensive equipment and rigid setups. The ability to bring LiDAR or accurate light sensors to a continuous range walking or mobile system creates new possibilities.
This significant processing step is built into several handheld devices that can be operated by almost anyone on a jobsite interested in capturing MUDD data like the exact site conditions during the course of a work day. The captured data can then be uploaded to a conventional laptop and saved or uploaded to the office or customer.
Having visualization of the data on site is an incredibly powerful tool that is easy to learn and use. The technology behind MUDD provides a cost-effective solution enabling contractors to take control of locating and mapping of their own projects. Using an accurate 3D-capture model documentation to anchor mark-ups and re-work notes, work progress or Health and Safety information is a value-adding proposition and overall time saver.
Sites captured can be annotated at the scene and saved using a few simple pulldown menus from a Locate Operations-specific toolbar. Combining photo images, point cloud technologies and site annotations into a single legible dataset will create millions of 3D data capture records from trenches and in utility chambers in a digital format that can
be positioned and uploaded to GIS or future Building Information Modelling (BIM) platforms.
If seeing is believing, then 3D MUDD locating and mapping may be a multi-faceted solution to a long-standing underground damage prevention and merged reality visualization challenge. Visualizing the One Call 811 mark-outs and the 3D point cloud of buried facilities can provide a risk management and conflict resolution tool that
saves time, money, and lives.
This capability is not far off, and will be able to absorb the site data captured by these scanners and techniques today. This digitization of locate documentation is an x,y,z-based process. Luckily, capture code and algorithms share common digital formats – the 3D information will not become unreadable or de-valued, and will serve as a continuum of information when a site is revisited and further scanned.
We all agree with the Common Ground Alliance (CGA) that damage prevention is a shared
responsibility. Therefore, it should be the task of all contractors, surveyors, engineers and inspectors to capture high-quality, useable underground utility data.
Maybe, I am not just a part of the problem after all. Maybe, I am a part of the solution. However, this much I know is true, I am still stuck in the “MUDD”.
Michael Twohig is Subsurface Utility Mapping SME at DGT Associates in Boston, Massachusetts. He can be reached at Michael.TwohigIMS@gmail.com or by phone