I’ve been working with LiDAR data for over 15 years and a lot has changed about the technology, but one thing remains the same: there are dozens of applications for LiDAR technology within the railroad. As the technology has improved it’s become easier to work with and understand, and more and more potential applications have been added to the list of possibilities.
While a LiDAR point cloud is a snapshot in time, it is a snapshot of absolutely everything within line of sight, measurable to an accuracy that rivals the surveyor or field worker with a tape measure in hand. Let’s think about that for a minute. Where is your next project: a mall renovation, airport terminal expansion, highway bridge redesign, or rail yard reconfiguration? In each of these scenarios, the time, effort, safety risk, and cost to survey every single structure and asset within the scene would be astronomical. With LiDAR, you make a handful of passes through the site with your scanner and the collection is done. Post process the data and now you have a centimeter-accurate 3D point cloud containing all the information you’ll need to get started on your project.
This is about as far as the casual users who have seen LiDAR have gone. Some have seen fancy fly throughs in and around structures to demonstrate the true “virtual world” or “digital twin” LiDAR can create but it’s still just that, a fancy representation. What we, as consumers, need is actionable information.
What I’ll do below is walk you through some real examples of what you can now do with that point cloud.
Clearances, in my humble opinion, are the bread and butter of LiDAR. Roads need consistent scans of all tunnels, bridges and other obstructions along their rail in order to confidently decide to move oversized objects (High & Wides) down their lines. LiDAR is an ideal tool for this. They can set it and forget it by mounting the LiDAR on an engine, geometry car, or track inspector Hi-Rail and scan on a consistent basis to build confidence in the current dimensions. Running those dimensions, or plates, through that LiDAR model provides a go/no-go decision for clearance managers and identifies infringements that need to be removed or remediated like overgrown vegetation, leaning posts or poles, bridge beams that may have shifted or come loose, or track shifts putting the cars too close to a platform, etc..
Ballast Deficiencies & Surpluses:
Ballast is ordered on an annual basis and it’s difficult to gather good quantitative data on individual local needs. With so many factors contributing to ballast movement throughout the year, capital plans are most often completed on a revolving basis so sections get new ballast every x years or based on x tons per year, etc. LiDAR clouds can be used to compare existing conditions with engineering standards and a specific measurement can be obtained, then a score assigned and compiled so purchasing can prioritize the needs based on actual measurements. In some cases, overages can be identified and regulators can then push or spread into areas with deficiencies. These can all be identified once an area is scanned, quantified and compared against standards.
Asset Identification and Change Detection (PTC Change Management):
I got my start in LiDAR on projects to identify assets and look for change. Now when I began, PTC wasn’t even a twinkle in our eye. It has since been bestowed upon us and it isn’t going away. Keeping track of hundreds of thousands of assets, to a high level of accuracy, on a very timely basis is extremely difficult if you don’t automate the process. LiDAR is the perfect solution as clouds can be used for comparison against themselves, looking for deltas. Roads own most everything in their right-of way and somewhere back at HQ sit several departments that own and are responsible for those assets. If you run LiDAR across your network for PTC and 6 months later decide to identify and inventory all your greasers, or heated switches, or Road Crossing Control boxes…no need to hire new surveyors, build a new mobile collection app or even revisit the field. You can build a new algorithm for the object and rerun that same LiDAR data to look for them. Any type of field data collection process to build an inventory is the most time consuming and resource intensive in the field collection phase. LiDAR eliminates that need for multiple assets.
Building Facility Inventory and Maintenance Inspection:
LiDAR can be used for long corridor scanning on a rail bound vehicle or carried on a drone. Drone-based LiDAR is great to provide large acreage areas with many complex structures and assets like buildings and other facilities. Rail yards are ideal for this as they are often very busy and dangerous environments for surveyors to be walking around. One of the pillars of Precision Scheduled Railroading is maximizing your assets, and buildings and facilities have often been overlooked as they are maintained and operated by a wide variety of departments and not assessed for utilization as a whole. A yard LiDAR inventory can quickly provide you counts of buildings, lat/long locations, areas, heights, opportunity to assign and assess, etc. Drones can also go places that are not easy to physically access like along roofs, gutters, piping and scaffolding, etc. Need to determine distances for a new fiber run between buildings, repaint a building, put on a new roof? These are all examples of where having a full point cloud of a yard allows you to go back and extract out info you may not have needed at first but now don’t need to go back to the field to obtain.
Legal Accident Scene Recreation:
My experience with LiDAR for legal use came after several of my “GIS Evangelizing” sessions where I spent time walking many departments through high level explanations of what LiDAR was and what coverage areas we had. Upon completing one of my sessions, I was asked if we had a specific section of track where there had been a crossing accident several years prior. We did and were in the area again and were able to recollect the same stretch. We now had LiDAR of the accident scene roughly one year prior and 10 years after the accident. We were able to match both 3D models based on several similar elevation marks on existing structures. With that, we were able to show that the elevation of the tracks and ballast had not changed but that the approach from the public street crossing had changed significantly. This evidence allowed our legal team to definitively prove our rail had not created an unsafe crossing, saving significant amounts of money.
One of the advantages of LiDAR is it picks up everything it hits. Vegetation is often overlooked as an asset LiDAR can identify. One reason is it is hard to quantify the vegetation since no one has the time nor patience to be notified of every branch along 20,000 miles of track that’s inside an envelope. Let’s look at it differently then. What if we quantified the “amount” of vegetation and then grouped those quantities in quarter mile increments? What if, as your LiDAR is scanning, we compared run over run and looked for changes in growth against time between runs and identified rapid growth?
What other ideas or “business questions” could be asked by those tasked with solving problems along the rail corridor? I’d like to translate those to our skilled team of LiDAR technicians who can turn data from a subjective issue into quantifiable decision making information.
One of the important line items for any construction project is field survey. This is necessary for both existing conditions or as-builts as well as final construction as-builts. I started my career in civil engineering, spending time out in the field doing traditional field surveys for these exact use cases. It can take days to weeks, depending on the size of the site, to conduct a full survey. Crews are often walking in and around equipment, structures, streets and driveways, etc. LiDAR allows that collection to be done in as little as one pass, handing off the asset extraction and creation of engineering plans to office personnel in a much safer, more efficient manner. Post-construction is done the same way with a final record of everything within line of sight that the laser picked up in as little as one pass of a vehicle. A railroad right-of-way can be collected at track speed in one pass, without engineering track time for ground based surveyors.
I’ve touched on several use cases at a very high level, but each one I have personally accomplished several times with LiDAR. If any of these cases ring true for you and your organization I invite you to reach out and ask me what else it can do or how to go into greater detail so you can realize the full value of LiDAR.
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