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Mobile LiDAR Surveys for Engineers-Efficiency, Accuracy, & a Forward Thinking Approach

By Mark McKlin, Professional Engineer at Zahner & Associates, Inc.

Civil Engineering has always relied on accurate surveys and survey data in order to fully understand the existing conditions and to produce the best possible design. Traditional topographic surveys used to take a substantial amount of time, and if the survey was of a lengthy corridor or specified route, the surveyed surface produced from said traditional survey had to be created from a grid of points collected. This grid was often not tight enough to produce a true representation of the actual existing surface. Using Mobile LiDAR to perform the same types of corridor and route surveys takes less time, is safer for field personnel and the existing surface created from the point cloud is much more accurate than a traditional survey could produce. Another advantage to using Mobile LiDAR over traditional survey methods is the ability to gather specific data from the LiDAR scan once the survey is complete. Site anomalies and variances from as built plans can be confirmed through the scan data after the fact without the need for returning to the site to check these issues. In addition, many LiDAR scanners shoot high quality photography that accompanies the scan data which again, is a major advantage over traditional methods. Overall, Mobile LiDAR surveys gather every detail of a site whereas the data gathered from a traditional survey is limited to the field crew’s interpretation of what data is needed for any given project.

One service that a Mobile LiDAR scan done by Zahner & Associates can provide is a quality survey of pedestrian facilities. Design standards by the ADA impose parameters that are very specific when it comes to the design of pedestrian facilities. A Mobile LiDAR scan of a street intersection for example can provide very accurate data of sidewalks, curb ramps, handrails, crosswalks, and signage etc. Existing conditions can be evaluated against the ADA standards and future designs can be executed in a cost-effective approach. Many municipalities have miles and miles of pedestrian walks and paths, many of which were built prior to ADA pedestrian facility requirements. These existing features can be scanned by Mobile LiDAR to produce a database of facilities while taking an inventory of features that do not meet the ADA standards. Municipalities can then streamline their projects to get their facilities within ADA requirements in the least amount of time.

Zahner & Associates believes that clients want accurate relevant survey data in a timely manner. Having an Engineer on staff can assist in this task. Many surveys are going to be used by design Engineers, and having an Engineer on staff helps to produce a survey that has future designs in mind. Site specific features are often the primary items that design Engineers are most interested in. Prior to surveys, many design Engineers relay their needs to ensure that all relevant data is collected. Having this discussion between Engineers creates a healthy client relationship and can help eliminate unnecessary work and the need to revisit a site to survey items that may have been overlooked.