Mobile lidar point cloud of a bridge identified for ad hoc collection


Indiana, like all states in the US, collects clearance data on every bridge in the state to meet federal reporting requirements and to inform infrastructure management needs. INDOT is obligated to report numerous bridge clearance measurements as part of the Federal Highway Administration’s National Bridge Inventory. Additionally, new construction and aging infrastructure impacts bridge clearances so measurements must be consistently taken to support uses such as oversize/overweight permitting. INDOT collects, maintains, and reports six types of clearance measurements and other data on over 2,100 bridges throughout the state. Unique to INDOT was the desire to perform ad hoc measurements throughout the state as construction activities warranted as well as perform statewide, programmatic measurement collection.

To meet these needs, INDOT selected Continental Mapping to collect data, derive measurements, and produce reports on each bridge. INDOT chose Continental Mapping because of the company’s ability to effectively manage statewide and ad hoc collection and the reliability of results from its mobile mapping system, from which the six required clearance measurement types are derived. INDOT and the travelers of Indiana’s roadways benefit from Continental Mapping’s experience, stellar safety record, and the value of a competitive price point assisting in keeping their highways safe.

Continental Mapping understood and executed INDOT’s requirements for multiple phases of data collection, both ad hoc and statewide. The ad hoc collections are performed as needed and prioritize bridges that, due to construction or other alteration, need verified clearance data quickly. The statewide collection is performed every two years to update the state’s complete inventory and satisfy federal reporting requirements.

INDOT required six unique clearance measurements for each bridge, including multiple types of both vertical and lateral measurements. Continental Mapping collected mobile lidar data and 360-degree imagery of each bridge. The mobile mapping lidar sensor captures up to 700,000 points per second and the cameras captures high-resolution spherical imagery. Measurements were derived from this data, and through rigorous in-field validation all measurements met or exceeded INDOT’s ±1-inch relative accuracy requirement.

Example of a custom SIS sheet Continental Mapping created for INDOT

Example of a custom SIS sheet Continental Mapping created for INDOT.

Continental Mapping used in-house tools to automatically populate Structure Information Sheets (SIS) for INDOT that provide information on each bridge to state employees and the public. The SIS reports include bridge location, bridge identification, photos, and all clearance measurements. The SIS reports are available online through INDOT’s website. The bridge information assists INDOT in satisfying federal reporting, managing the state’s bridges, and is key to keeping Indiana’s highways, and the millions of people who use them, safe.