The Benefits of Mobile LiDAR in Transportation Projects
Mobile LiDAR (Light Detection and Ranging) is an emerging technology that not everyone understands. Even geomatics professionals sometimes have a hard time explaining what it is, and how it can be a benefit to the transportation industry.
To counter that, researchers and professionals from across the country developed “Guidelines for the Use of Mobile LiDAR in Transportation Applications,” a national reference guide offering best practices for integrating mobile LiDAR into state departments of transportation (DOT) workflows. The guide is useful for novices and those with a background in working with mobile LiDAR data, as it provides a technical section in addition to an educational section among its 243 pages.
“You don’t necessarily need mobile LiDAR expertise to pick up the document and use it,” said Michael J. Olsen, professor of geomatics at Oregon State University, who led the team of researchers that produced the guide. “However, the more you know about it and the more you use it … obviously the easier it’s going to be to apply.”
That’s why the guide is necessary. Many state DOTs have been muddling through mobile LiDAR integration on their own. Some states, such as California’s Caltrans, have developed – or are developing – their own best practices. The national report, funded by the Transportation Research Board and the National Cooperative Highway Research Program, is designed to assist local transportation agencies with the adoption of mobile LiDAR by establishing a “standard reference and a common basis for understanding and communication,” the report states.
During a webinar to discuss the report, Olsen said the guidelines aren’t intended to replace state or other groups’ efforts to develop best practices but to work in concert with them. Indeed, all 50 state DOTs responded to the research team’s questionnaire about mobile LiDAR use. The results showed that state DOTs see the value of mobile LiDAR, despite some roadblocks, as mobile LiDAR data collection rates are doubling every 18 months.
The biggest issue, of course, is cost, since many state transportation budgets are cash-strapped. Repeatedly during the webinar, Olsen and others pointed to the cost savings of mobile LiDAR adoption. That’s because the data can be used over and over by various state or local agencies. Developing partnerships with these other agencies will help transportation departments reduce the initial cost, which the research team concedes is high.
Fred Persi, principal at Persi Consulting, said cost savings are enormous because surveyors don’t have to return to the field time after time to collect additional data for different projects. When everyone is using the same data, costs of acquiring that data is reduced, he said. It also eliminates the question of which set of data can be trusted, since the integrity of mobile LiDAR is typically paramount. In this way, state transportation agencies can maximize their investment with only one vehicle in the field.
“If you can collect this data once … it can be mined over and over and over again by multiple groups and multiple people doing multiple things,” Persi said.
Olsen emphasized that point, saying that a project’s lifecycle doesn’t end when that particular project is complete. “The missing link … for any engineering project is that we’re very good at acquiring information before and throughout the project, but then when the project is completed, we don’t really update our records properly,” Olsen said. “We’re lucky if we get as-built drawings that are digitally stored and even then we don’t tend to update it. Really, the key to a lifecycle is to continue to use these technologies to update it afterward and create a very accurate model of what’s there.”
In other words, that data needs to live so it can save money on future projects in the same location. The 3D, digital models that mobile LiDAR provides can be used as a base map time and again. Adoption of 3D digital models by transportation agencies throughout the country is on the rise, as the federal government has provided funding through initiatives such as MAP-21, the federal government’s Moving Ahead for Progress in the 21st Century Act.
Mobile LiDAR, obtaining highly accurate 3D information by driving a collection vehicle at highway speeds, can help usher in this new paradigm for state DOTs; it is often called the digital highway or transportation information modeling.
The full transition from 2D paper modeling to 3D digital models throughout the United States could take another decade. That’s why education – and how geospatial professionals might educate upper management – is a key component of the guide. Olsen said mobile LiDAR is gaining popularity since those who use it are reportedly satisfied with the results. One drawback they found, researchers said, is that users of mobile LiDAR could have utilized it in other ways on a particular project had they known more about how to use the data beforehand.
Gene Roe, editor at LiDARnews.com, suggested on the webinar that mobile LiDAR has many applications for the transportation industry, including safety, operations, maintenance, construction, project planning, project development, research and asset management. Along with Marcus Reedy, vice president and director of geomatics for David Evans & Associates, he advised that transportation groups need to invest in the proper training of personnel.
Reedy also suggested that agencies invest in computing infrastructure, since mobile LiDAR file sizes are large and high-speed networks are required to process the data. Managing all that data is an issue state agencies and geomatics professionals are struggling with, since not many have switched to a cloud-based format. The guide says that in order to maximize the investment of mobile LiDAR, the volume of data will have to be managed in a way that “insures timely and streamlined access to the data across the entire enterprise.”
Different strategies for managing the data are explored in the document. One key is finding the right person. The guide recommends that an experienced geomatics professional should be involved throughout the entire road construction process.
“If you can get somebody with a passion for this, who likes to work with point clouds and can get into the processing, into the numbers side of the game, they would probably be a good person to have,” Reedy said.