Express lanes / public transport priority
Delays induced by the operation of traffic signals typically account for 10% to 25% of the total travel time of buses. This has an impact on the quality of the service for users, may lead to lower public transport ridership, and has impact on fuel consumption and related emissions of public transit services. The creation of bus lanes (or express lanes) and the implementation of transit signal priority (TSP) for buses can enhance their efficiency and travel times. With TSP, buses are equipped with sensors that allow them priority when approaching traffic lights. TSP strategies can reduce CO2 emissions, as well as enhance the impact of other measures, such as a change in fuel source. Nonetheless, traffic management measures, and particularly TSP, can also increase CO2 in a given area, e.g. if these measures cause an increase in congestion for other vehicles that offsets any emissions reductions achieved by more efficient bus travel.
New forms of TSP are being developed by using intelligent transport systems and new signalling methods to be able to enhance their mitigation potential, as well as to reduce the negative externalities regarding other vehicles. Traffic management centres and vehicles will share traffic information in standardised format, and based on such real-time data individual vehicles can obtain guidance for time-, energy- and noise-efficient travel. Intermittent bus lanes or bus lanes with intermittent priority are also solutions that could be considered, depending on the capacity of the road under consideration.
Estimating the impact of bus lanes (with or without TSP) on CO2 emissions is difficult, especially when taking into account the effect they may have on traffic overall. It is often assumed that express lanes lead to a reduction of CO2 emissions, but results depend on road network and mobility patterns (for instance through the possible increase in congestion for other vehicles). Mitigation potential can also vary across space. Although CO2 reductions from traffic management measures could be substantial on one particular road, their wider impacts across the transport network as a whole could still be marginal, or even negative.
Creating bus lanes requires minor infrastructure investments for road signage. If bus lanes are introduced at the expense of roadside parking space, it can imply a loss in terms of revenues from parking fees. Introducing TSP implies the equipment of traffic lights and buses with the necessary technology.
In the United States, it was estimated that implementing TSP ranged from USD 8 000 (US dollars) to USD 35 000 per intersection.
Prioritising public transport through bus lanes or TSP generally incurs travel time savings. For instance, a jumper lane TSP (a short stretch of special lane with a leading transit signal phase interval to allow buses to bypass a waiting traffic queue) can reduce bus delays by 3% to 17% compared with a mixed-lane TSP. The creation of bus lanes that are open to other vehicles can incentivise the use of car-sharing services, alternative fuel vehicles or smaller vehicles, which can incite more sustainable travel behaviour reduce overall traffic emissions.
Giving priority to buses in urban areas can contribute to increasing road congestion for other vehicles, and therefore an overall increase of emissions (e.g. in Thessaloniki, the implementation of a bus lane led to an increase of emissions in the road axis where the lane was created [+6.7% for CO2; +6.9% for carbon monoxide and +2.7% for hydrocarbons; wider emission impacts were not assessed).
ITF (2021) Transport Climate Action Directory – Express lanes / public transport priority
https://www.itf-oecd.org/policy/express-lanes-public-transport-priority
Aakre, E. and Aakre, A. (2017) Simulating transit priority: Continuous median lane roundabouts, https://doi.org/10.1016/j.procs.2017.05.400
Alam and Hatzopoulou (2014) Reducing transit bus emissions: Alternative fuels or traffic operations?, https://doi.org/10.1016/j.atmosenv.2014.02.043
Baker et al. (2002) An Overview of Transit Signal Priority, https://trid.trb.org/view.aspx?id=723986
Balke et al. (2000) Development and evaluation of intelligent bus priority concept, https://doi.org/10.3141/1727-02
Basbas et al. (2011) The implementation of a contra flow bus lane in the city of Thessaloniki: Energy and environmental impacts.
Chiabout, N. ,Xie, X. and Leclercq, L. (2012) Road Capacity and Travel Times with Bus Lanes and Intermittent Priority Activation. Analytical Investigations, https://doi.org/10.3141/2315-19
Dion et al. (2004) Evaluation of potential transit signal priority benefits along a fixed-time signalized arterial, https://doi.org/10.1061/(ASCE)0733-947X(2004)130:3(294)
Goinga, Y. W. A. () The effects of bus priority on the delay and emissions of busses and the other vehicles A Copenhagen case study, https://pdfs.semanticscholar.org/a276/f189621b6dcf96125bb827b01f1a5ab4f205.pdf
Legislative Analyst's Office (2000) HOV Lanes in California: Are They Achieving Their Goals? http://www.lao.ca.gov/2000/010700_hov/010700_hov_lanes.html
Li et al. (2012) Evaluate bus emissions generated near far-side and near-side stops and potential reductions by ITS: an empirical study, https://doi.org/10.1016/j.trd.2011.09.012
McDonnell, S., Convery, F. and Ferreira, S. (2008) Using Bus Rapid Transit to Mitigate Emissions of CO 2 from Transport, https://doi.org/10.1080/01441640802012920
Sanz Cañelles, D. (2009) Análisis operativo y medioambiental de los sistemas de prioridad semafórica, https://upcommons.upc.edu/handle/2099.1/8476
Urban Mobility Solutions () Solutions factsheet- 2-1 Dedicated bus lanes.
Viegas J. et al. (2006) Demonstration of The Intermittent Bus Lane in Lisbon.. IFAC Proceedings Volumes, Volume 39, Issue 12, January 2006, Pages 239-244, https://doi.org/10.3182/20060829-3-NL-2908.00042
Vujic, M. Mandzuka, S. and, Greguric, M. (2015) PILOT IMPLEMENTATION OF PUBLIC TRANSPORT PRIORITY IN THE CITY OF ZAGREB, https://hrcak.srce.hr/140945
Wang et al. (2016) Emissions Analysis for a Transit Corridor Under Different Improvement Strategies, https://doi.org/10.3141/2570-08
Zhou and Gan (2009) Performance of Transit Signal Priority with Queue Jumper Lanes, https://doi.org/10.1177/0361198105192500127
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