VSS 9 2015

2 | Lane choice at C2 related to bus position and flow state. 2 | Choix de voie en C2 selon la position du bus et l’état de la circulation. 2 | Fahrspurwahl an der Stelle C2 in Bezug auf die Busposition und den Verkehrsflusszustand. The position of each vehicle respective to the bus was re- corded at the locations C2 and C3, and classified as follows: • No bus influence • Within bus influence – In front of bus – Next to bus – Behind bus In the next step, each vehicle was checked if it discharged at capacity or not. A capacity state implies that cars are travel- ling with the smallest headways that they are willing to keep. Here, it was assumed that during the capacity states, vehicles would pass C1 with headways of less than 2.5s. With this criterion, at C1, where vehicles arrive more or less randomly distributed, capacity could be calculated by dividing the number of cars during one capacity period by the duration of the period. At C2, the random distribution is disrupted by the traffic signal. To calculate capacity there, a more complicated algo- rithm was developed, which contrasted theoretical (or “vir- tual”) departure times (if there were no traffic signal) with the actual departure times. C1 represents the capacity of a dedicated bus lane system, while C2 and C3 typify the mixed road use system. Since the same vehicles pass both systems, capacities can be compared and delays can be calculated. Results Lane choice At C2, drivers are free to change to the right lane or stay in the left lane. As expected, in the absence of a bus, the utilization of the left and the right lane is almost balanced. However, when there is a bus within the traffic flow, the right lane is used less often by the vehicles driving ahead of the bus. Probably, some drivers want to be sure not to block the following bus and thus stay in the left lane. The cars next to the bus naturally flow in the left lane, while the following drivers mostly choose the left lane as well. As the buses usu- ally go slower than other traffic, because they have to halt at bus stops, a. o., the cars can avoid additional delays by driving in the left lane. However, the preference of the left lane could not be observed during capacity periods. In times when demand is high, the distribution of vehicles to the two lanes was almost perfectly balanced out. Drivers then accepted sharing the rightmost lane with buses in order to better exploit the road’s entire capacity. Dynamische Busspuren in Zürich: Auswirkungen des multimodalen Verkehrs auf städtische Netzwerke Eine übliche Strategie, um den öffentlichen Verkehrsmit- teln in städtischen Verkehrsnetzen Priorität einzuräumen, besteht in der ausschliesslichen Zweckbestimmung von Busspuren. Indem Busse vom allgemeinen Verkehr ge- trennt werden, wird die Minimierung von Verspätungen im öffentlichen Verkehr ermöglicht und gleichzeitig der all- gemeine Verkehr entlastet. Die neuere Forschung hat das Konzept der dynamischen Busspuren vorgeschlagen, um städtische Strassen besser zu nutzen. Um deren Vorteil für die städtischen Verkehrsnetze in der Schweiz einzuschät- zen, wurden die Wechselwirkungen von öffentlichen Bus- sen und Autos empirisch analysiert. Die Ergebnisse zeigen auch, wie unterschiedliche Busbetriebs-Strategien sich auf die Auto-Belastbarkeit einer Strasse in Zürich auswirken. DE FACHARTIKEL | ARTICLES TECHNIQUES | 29 VSS_SV_09_2015.pdf 29VSS_SV_09_2015.pdf 29 28.09.15 10:4028.09.15 10:40 VSS_SV_09_2015.pdf 29VSS_SV_09_2015.pdf 2928.09.1510:4028.09.1510:40

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