Technology Spotlight: LiDAR Improves Efficiency and Accuracy

At RJN, we always stay abreast of the latest technologies in the industry. If there is a new technology available that can make our field investigation techniques more efficient, accurate, and cost-effective, then we will definitely pursue it by either acquiring it ourselves or collaborating with contractors who possess the new technology. In both cases, be it RJN or a contractor with whom RJN is working, the teams responsible for using the latest technology will be experts with it, able to maximize that technology’s capabilities.

But having access to the latest technologies and being trained on how best to use those technologies is not enough—experts like the engineers and technicians at RJN also need to exercise good judgment, strong strategies, and creative problem-solving to decide when using these new technologies would be most beneficial to our clients.

LiDAR is one of many multi-sensor technologies. Multi-sensor technologies may use one or more of the following features:th

  • CCTV/HD CCTV
  • Laser
  • Sonar

 

Why Use Multi-Sensor Technology

With regards to sewer inspection programs, the RJN team may choose to conduct multi-sensor inspections using advanced technology when significant flow exists in interceptors or on large diameter lines; when debris under the flow needs to be measured; when corrosion above the flow needs to be measured; and when capacity of pipes needs to be assessed and the extent of deterioration needs to be determined.

Other reasons why clients and RJN might choose to use multi-sensor inspection methods include when there is only remote access to manholes (for example, in forest preserves and park districts) as well as when the sewers haven’t been inspected for a very long time, if at all, and it is suspected that there might be a great deal of debris and/or corrosion. Another reason is that many of these technologies take less time than other more traditional methods of inspection. In addition, they often provide a more comprehensive and detailed picture of the system being studied.

Some multi-sensor inspection technologies are better under certain circumstances than others. Despite some limitations, each type of multi-sensor technology has major benefits when used in the appropriate situation. Let’s take a more detailed look at one of these technologies: LiDAR.

What Is LiDAR?

LiDAR stands for “Light Detecting And Ranging.” It is active remote sensing technology that measures distance with reflected laser light.

lidar

How Does LiDAR work?

LiDAR measures the distance to surfaces by timing the outgoing laser pulse and the corresponding returns. The formula for distance in this case is time multiplied by speed of light divided by 2.  In keeping track of the angle at which the laser is fired, the technicians and engineers can calculate the X, Y, and Z position of each “return” (data point).

LiDAR inspection works like radar by emitting photons in all directions to create a 3-dimensional model of the pipe.  It identifies pipe wall conditions, including bends in a pipe, measures inside of offset joints, and holes in the pipe and laterals. It also measures inside diameter so that remaining wall thickness can be estimated.

There is also such a technology as “mobile LiDAR.”  Next year we will feature a profile of a major stormwater mapping project in San Antonio that used mobile LiDAR, among other advanced technologies.  Bookmark our blog and be on the lookout for that feature in the coming soon!

Benefits of LiDAR

LiDAR has many benefits, including:

  • Providing highly accurate data for rehabilitation methodology
  • Predicting life expectancy of existing pipe
  • Emitting quantitative data for proactive decision-making

LiDAR at Work

RJN effectively used LiDAR on many projects. For example, on the Sewer System Analysis of Basins 11, 14, and 16 performed as a subcontractor with Fisher & Arnold for West Memphis, Arkansas, RJN used LiDAR to inspect 2,182 LF of 42-inch reinforced concrete pipe that transported the majority of the city’s wastewater flow to the treatment plant. In using LiDAR, RJN was able to gather and analyze a fuller picture of the sewer system conditions and determine the remaining useful life of this critical infrastructure.  Sections of the pipeline that suffered thecorrosion most severe corrosion were identified.  With insights gathered from LiDAR, RJN made useful recommendations for repair.  The LiDAR was much more advantageous to the study for that large diameter part of the sewer line than the usual CCTV would have been.

 

Overall, by bringing our clients the latest and greatest advanced technologies like LiDAR, RJN improves results while also saving time and money.