In Germany, there are high capacity roads which are used by long-distance traffic and local traffic while relieving the subordinate road network. The crosssection of these roads which are designed urban or motorway-like consists of at least two lanes per direction of travel, which enable them to handle high traffic volumes. High capacity roads are not a category in the existing guidelines of the German 'Road and Transportation Research Association' and therefore there are no corresponding design recommendations. The existing design elements in some cases differ significantly from the currently valid rules for existing categories of urban streets or motorways. The main task of this research project was the development of design parameters for high capacity roads in consideration of traffic safety, travel speed, noise protection measures as well as aspects of urban development and urban planning. At first, a terminology for urban and motorway-like high capacity roads was developed based on a literature research. On this basis, a survey on roads of this type was conducted among German municipalities with more than 200.000 inhabitants. It was determined that a large number of high capacity roads exist in the German road network. On the basis of the survey of the municipalities, a research collective of 13 high-speed lines was finally selected for further detailed analyses. The detailed analyses provided insights into the different areas of analysis and impact. It was recognizable that high capacity roads fulfill their traffic and development functions as far as possible efficiently and safely. Elevated intersections proved to be more beneficial compared to non elevated intersections regarding the analyses of the travel speed and traffic safety. It should be noted that at elevated intersections the pedestrian and bicycle traffic is often relocated to the surrounding road network and thus, compared to non elevated intersections, no corresponding effects on the travel speed and traffic safety occurred. However, if aspects of accessibility for road users of non-motorized individual traffic, urban planning integration or noise protection aspects are consulted, non elevated intersections are more suitable than elevated ones. Priority-controlled intersections and land accesses with low traffic volumes did not adversely affect the traffic speed or the traffic safety of high capacity roads. Furthermore there were no negative aspects of accessibility for road users of the non-motorized individual traffic and urban integration. When considering the noise emissions of high capacity roads, closed buildings with more than three floors also proved to be suitable, also with regard to urban planning aspects, for shielding the downstream areas. The developed design parameters and recommendations were intended to introduce the so far nonexistent road type of the high capacity road into the existing guidelines of the German 'Road and Transportation Research Association' taking into account not only transport issues but also urban planning and urban development aspects. (Author/publisher)
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