Influence of Roadside Impedance on Speed and Capacity of Urban Streets

Abstract

Abstract The elements of roadside friction have been defined as those activities that are taking place on the side of the road or even on the road, and which may affect on the uninterrupted traffic flowing. These elements are usually very common in highly populated regions in the developing countries, while they are random and low in the developed countries. In this research, the roadside friction elements were limited to on-street parking of vehicles first and the second side, vehicles stopping temporary and pedestrians crossing. Three links of arterial streets were chosen in the city of Baghdad; Palestine Street and Palestine Street, Zayouna region and 14-Ramadan Street, AL Mansoor. The data had extracted during two periods: the peak period and the non-peak period. The flow-density relationship was plotted and the values of the correlation coefficient (R2) were extracted for the two periods. A comparison was made between the empirical and extracted free-flow speed from the field. The percentage difference in FFS for Palestine Street was the maximum, as it reached 29.13%. The percentage reduction results in the capacity values display that Palestine Street, Zayouna Region has a maximum result which was 33.92%. While the minimum percentage 4.07% was for 14-Ramadan Street, AL-Mansoor region. This study spotlights through the results obtained the need to include side friction elements in traffic-related studies, especially for proper planning of urban roads.