Boston-based startup StreetScan has developed vehicle-mounted sensors that inspect road pavement to provide empirically based surface and subsurface assessments for use by municipal road maintenance operations.

StreetScan vehicles carry out the monitoring in the normal flow of traffic and afterwards deliver a pavement condition map through a web application that provides detailed road condition data to assist decision makers in maintaining and improving their road network.

Diagram of the StreetScan road-monitoring process. Image credit: StreetScan. Many cities allocate their maintenance budgets based on pavement condition surveys that rely on surface observations carried out by inspectors. According to StreetScan, these can be costly, time consuming and intrusive on the traveling public.

StreetScan's system collects pavement-related data via acoustic, radar and optical sensors:

· Acoustic technology uses tire-induced vibrations and sound waves to determine surface texture, roughness and overall condition. The waves are recorded with directional microphones and a dynamic tire pressure sensor.

· Millimeter-wave surface radar array technology characterizes road profile and rutting depth and maps surface defects and features such as potholes, water or metal (manholes and other utility covers).

· Video camera is used to capture surface defects for verification of results from the other sensors, analyzing cracks for their type and severity.

· Ground-penetrating radar arrays map subsurface information such as pavement layers (thicknesses and electromagnetic properties) as well as rebar corrosion and delamination of bridge decks.

In its first year of operation, StreetScan has already mapped hundreds of miles of roads using its sensor technology for municipalities around Massachusetts, including Beverly, Littleton and Newton.