Overview
Surface Inspection for Better Roadways
The transportation industry uses 3D sensors in a variety of applications such as inspection of pavement for highways and airport runways. These applications include profiling of the surface to determine texture and wear, which have an impact on ride quality, traction and noise generation.
Pavement is inspected during construction to ensure desired quality levels are met, and over the lifetime of the pavement to monitor wear. Accurate surface inspection helps to determine short-term maintenance and repair priorities, as well as measure the efficiency and effectiveness of maintenance policies. The result is improved maintenance, better roads, fewer accidents and lower costs for motorists.
Transportation applications place extreme demands on 3D sensors. Robust operation is mandatory as sensors must operate in an uncontrolled outdoor environment, exposed to sunlight, large temperature variations, shock and vibration. Surfaces inspected vary from black asphalt to bright new concrete.
LMI has been a leading provider of 3D sensors to the transportation industry around the world, since 1979. Our current RoLine sensors are the latest generation of laser line based 3D sensors for transportation applications, to reliably measure today’s complex coarse textured pavements, including tined surfaces.
The Transportation Division works closely with System Integrators, OEMs and government agencies to deliver the most effective solutions for their particular 3D sensor needs.
Applications
New Pavement Inspection
Measuring pavement smoothness during construction determines conformance with specifications and indicates if repair action, such as grinding of nonconforming sections, is required.
During construction, inspection is carried out by lightweight profilers, typically instrumented golf carts or ATV’s. One or two LMI RoLine sensors are mounted on the profiler coupled with accelerometers, distance measuring devices, GPS sensors and data acquisition systems. The profiler is driven down the pavement at low speed, providing detailed profiles for analysis.
In Service Inspection
In service pavements are monitored for wear, profile degradation, roughness, cracks, and rutting, using high speed profilers. High speed profilers are typically trucks, fitted with two RoLine sensors, one in each wheel path, and similar instrumentation to lightweight profilers.
In service inspection adds a further challenge, since it is highly desirable to carry out inspection at highway speeds to avoid traffic disruption. Today’s RoLine 3D sensors provide very high sampling rates to satisfy these requirements.
Tined Road Surface Inspection
Cement Road surfaces are tined, or grooved, to allow water to flow away from the surface. The effective road to tire contact is determined by the width of each tine at the top surface. 3D road scanning that uses a series of single laser points across the vehicle may have each laser point projected on top of the tine or down into the groove at any instance in time as the road inspection vehicle is travelling down the road. This is a limitation that makes it challenging to determine what is really being measured, the top or bottom of the groove.
To overcome this LMI has developed the RoLine 1130 and 1145 sensors to project a laser line across the road surface. This allows the 3D sensor to effectively measure the full profile of the tines (grooves and peaks) on the road surface. The surface along the peaks of the tines which represent the tire contact is called the 'Bridge' value. To make the RoLine an effective 3D sensor for the road inspection industry, it has a built in algorithm to continuously calculate the 'Bridge' value at highway speeds.