Alignment Data Collection of Highways Using Mobile Mapping and Image Analysis Techniques

The Mobile Mapping System (MMS) is an advanced tool useful in the survey of linear infrastructures such as highways. One of its main applications is the collection of three-dimensional data used to derive the geometric characteristics of roads (i.e. alignment, lane width, shoulder dimensions) and other elements of the road surroundings (i.e. traffic signs, lighting systems, barriers, drainage elements). It is a tool which is useful in several applications and research fields (i.e. road cadastral, safety and human factor studies, road infrastructure quality control). In this paper, the results of an investigation dedicated to the evaluation of the geometric characteristics of highway alignment are presented. The program investigation has been conducted by using image analysis techniques to process the data collected by a dedicated MMS. A prototype vehicle has been developed and fitted out with three geodetic GNSS receivers, a low cost inertial measurement unit (IMU) with a built-in GPS receiver (GPS/IMU) and a webcam. The highway alignment has been derived as the average point of the two trajectories followed by the MMS or alternatively in accordance with the horizontal markings of the pavement. The trajectories have been derived from GPS/IMU data processing while the markings have been automatically recorded by a webcam. Each frame has been geo-referenced on the basis of the data collected from the GPS/IMU sensor. A data validation procedure has been carried out to verify the accuracy of the proposed surveying method