On January 1, 2012 the Federal Government launched a Germany-wide field trial with long heavy goods vehicles (HGV). This trial has different focuses based on a special traffic ordinance. This regulation requires a scientific monitoring for the field trial by the Federal Road Research Institute (BASt). Reasons for the field trial was to find effects of long HGV on traffic safety, traffic flow, traffic quality and on the geometric design of traffic facilities which are caused by long heavy goods vehicles. The present study describes in this context the trafficability on at-grade intersections and roundabouts on German motorways. To this aim, the real operation on intersections of the long HGV has been analysed. Therefore the driving behavior, the driving geometry and the resulting space required was measured of each long HGV. The measuring systems were digital cameras and laser scanner. The laser scanner recorded the edge of the HGV with coordinates and save this data in a local coordinate system. The data was imported in a CAD-software, and a tractrix curve for each HGV was prepared. In the end the tractrix curve of each long HGV were compared with a normal truck. The real measured tractrix curves of the long HGV would fit on guideline planed intersections (with exception of the tested long HGV type 2). The swept area of the long HGV is coverd of the intersection. To get this result, the long HGV must drive a ideal line on the intersection. This ideal driving line was not measured in this trial. The drivers were always a bit too far to the right or left site in her driving line. So they drove over the hard shoulder or the neighboring lanes (not the banquet). At business and under pressure of time, deviations of the ideal driving line must be accept. In the short term it would be more tolerable to drive over the hard shoulder on intersection. But in the long term is a widening of the driving lanes useful. On roundabouts the long HGV needed all available space, to drive one or three-quarters. In a three quarter turn in the roundabout, the outer edges covered the hard shoulder. In a full turn in the roundabout, the long HGV overran the outer boundaries of the roundabout in the exit lane. The lowest deviations from the reference vehicle have type 1 and 5. This long HGV are better or corresponded with the reference vehicle. The tractrix curve of the tested long HGV (except type 2) matched together with the geometric design of at-grade intersections while driving with ideal driving line. When there are small deviations from the ideal driving line, the long HGV drove over the hard shoulder. (Author/publisher)
Samenvatting