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 ride quality and texture, which influences friction and noise generation. Pavement is inspected during construction to ensure desired quality levels are met, and during the lifetime of the pavement to monitor wear to determine short-term maintenance and repair priorities, to ascertain the efficiency of maintenance policies and for long-term network evolution. The result is improved maintenance, better roads, fewer accidents and lower costs for motorists.

Transportation applications place extreme demands on 3D sensors. Robust sensor operation is mandatory, operating in the uncontrolled outdoor environment, where sensors are exposed to sunlight, large temperature variations, shock and vibration. Surfaces inspected vary from black asphalt to bright new concrete.

Since 1979, LMI has been a leading provider of 3D sensors to the transportation industry, around the world. 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 & Original Equipment Machine Suppliers and government agencies to deliver the most effective solutions for their particular 3D sensor needs.

Applications

New Pavement Inspection

Measuring pavement smoothness for ride quality 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 allow the 3D sensor to effectively measure the full profile of the tines (grooves and peaks) on the road surface.  The top surface along to peaks of the tines that represent the tire contact is called the 'Bridged' value.   To make the RoLine an effective 3D sensor for the road inspection industry, it has a built in algorithm to measure the 'Bridged' value continuously at highway speeds.