VSS 9 2015

1.18) in order to compare C1 and C2. At C2, two lanes are ac- cessible to cars instead of only one. The comparison showed that capacity at C2 was almost exactly doubled thanks to the second lane, i.e. the capacity per lane is the same at C1 and C2. Hence, no smoothing effect could be observed at C1 de- spite the segregation of the two modes. The presence of a bus in the mixed-use road reduces capacity by up to 36 % (behind a bus) and by 21 % on average. This cannot be explained with the lane choice, since both lanes were equally charged during capacity periods. The capacity drop must result from the reduction of travel speed under the influence of a bus. However, the capacity of a mixed-use road is always higher than in the dedicated bus lane system. As expected, general traffic benefits from the second lane. Conclusions Two different bus operating strategies were empirically compared, namely mixed-use lanes and dedicated bus lanes. The results show that the car capacity per lane remains the same if a lane is dedicated for bus-use only. While this result contradicts the expectations from the literature based on HOV lanes, it could be expected for congested states in urban areas where traffic lights completely stop cars (i.e., very little opportunity for lane changes remain in queued conditions). However, in mixed-use conditions, the presence of a bus in the traffic flow was found to reduce the capacity by 20% due to the lower speed of the bus. There are many dedicated bus lanes in Zurich. The results of this work indicate that at these locations a dynamic bus lane would ameliorate the flow conditions of general traffic: All capacities measured at C2 and C3 are higher than at C1, where there is a dedicated bus lane. One should also consider the fraction of time during which vehicles are affected by buses: About 20 buses per hour pass by Winzerhalde, which is a medium frequency. The dataset includes 190 vehicles influenced by a bus and 1170 vehicles that pass C2 when there is no bus present. Therefore, only about 14% of all ob- served vehicles suffered delays caused by the bus during the morning peak. In a dynamic bus lane instead of mixed road use, this percentage would certainly be a bit higher, because the influence of the bus would reach further downstream. Also, the flow reductions would be greater, since the right lane would be closed ahead of the bus. Still, capacity would not fall under that of a lane next to a dedicated bus lane at any time. One can thus reasonably assume that even with much higher bus rates, cars would benefit from a dynamic bus lane. The results are for a specific site. It is difficult to conclude that a smoothing effect would not be observed anywhere in an urban network, but it is expected that this effect would not be as pronounced as previously observed on highways. Also, note that drivers in Zurich are typically very respect- ful of public transportation modes. Therefore, it is probable that the observed damage caused in the traffic flow by buses is close to the upper bound of what would be observed in general. JEUDI 26 NOVEMBRE 2015 DÈS 8 H CONFÉRENCE JERI «PROBLÈMES INSOLUBLES RÉSOLUS» SwissTech Convention Center, EPFL Lausanne www.confjeri.ch Programme et présentations: Teneur en liant optimale des enrobés avec recyclé Sara Bressi, EPFL-LAVOC, Lausanne Revêtement bitumineux hors-norme pour le Viaduc de Millau Dr François Olard, Eiffage Travaux Publics, Lyon (France) Arrêts de bus: «Success stories» Dr Mehdi Ould Henia, Nibuxs sàrl, Ecublens Fin de la congestion récurrente sur l’autoroute entre Morges et Ecublens Jade Chapoton, RGR Ingénieurs conseils, Lausanne Réduction des risques avec les enrobés phono-absorbants Jean-Louis Cuénoud, Infralab SA, Romanel/Lausanne Outil de calcul de la juste température d’enrobage pour l’éco-conduite des centrales Dr Bertrand Pouteau, Eurovia, Bordeaux (France) Opération «coup de poing», le remplacement du pont de la Mouline à Lausanne Olivier Simon-Vermot et Jean-Hugues Marchal, MARTI SA, Lausanne Renseignements et inscription: Laboratoire des voies de circulation (LAVOC), EPFL ENAC IIC LAVOC Station 18, CH–1015 Lausanne Tél: +41 21 693 2345, fax: +41 21 693 6349 | secretariat@confjeri.ch | www.confjeri.ch Coût: Participation à la journée fr. 270.- (comprenant documentation, pause café, apéritif, repas de midi avec boissons) Anzeige VSS_SV_09_2015.pdf 31VSS_SV_09_2015.pdf 31 28.09.15 10:4028.09.15 10:40 Tél: +41216932345, fax: +41216936349 | secretariat@confjeri.ch | VSS_SV_09_2015.pdf 31VSS_SV_09_2015.pdf 3128.09.1510:4028.09.1510:40

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