The smoothing effect of carpool lanes on freeway bottlenecks

Cassidy, Michael J.; Jang, Kitae; Daganzo, Carlos F.

doi:10.1016/j.tra.2009.11.002

Cited by 23 publications

(23 citation statements)

References 16 publications

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“…Later studies focused on the effects of BRT systems on both cars and buses (i.e, Shalaby, 1999;Japson & Ferreira, 2000;Currie et al, 2007;Arasan & Vedagiri, 2010;Cassidy et al, 2010). Using various methods (such as simulation or theoretical evaluation), these studies often conclude that it is difficult to justify the implementation of BRT systems if the effects on car traffic are also considered.…”

Section: Bus Priority Strategies Targeted To Linksmentioning

confidence: 99%

“…The authors determined that for cars to remain operating at an acceptable level of service (C), a volume to capacity ratio of approximately 0.55 and a road space allocation of 34% (for a 3 lane roadway) for buses would be needed. Finally, theoretical analysis conducted in Cassidy et al (2010) showed that it is possible to reduce total VHT by segregating bus and car traffic on circular beltways when the smoothing effect is considered. However the analysis assumed that bus demand is fairly high and was further idealized in that it ignored many complications of real-world traffic such as driver behaviour.…”

Section: Bus Priority Strategies Targeted To Linksmentioning

confidence: 99%

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Strategies for sharing bottleneck capacity among buses and cars

Guler

Cassidy

2012

Transportation Research Part B: Methodological

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In urban settings where space is at a premium, bus lanes can often only be created via the conversion of existing general-use lanes. This can be politically infeasible in cities where bus flows are low, because the converted lanes would be under-utilized and thereby squander road space. The roadway bottlenecks would then as a result create even greater delays and queuing for car traffic.The present thesis explores novel ways in which buses and cars might share lanes within select bottlenecks. Details of these shared-lane strategies vary, depending upon a bottleneck's local operating conditions. In all cases, cars would be inserted into a shared lane in ways that impart few delays to the buses. These insertions would allow for the unused space between buses to be used, lessening the damage otherwise incurred by car traffic at bottlenecks. Hence, by reducing the car delay at bottlenecks it may become feasible to deploy ordinary bus-lane conversions elsewhere throughout a city's road network. The ordinary lane conversions would enable buses to bypass the car queues that still form at bottlenecks.Analytical assessments unveil the wide range of bus flows for which these strategies increase a bottleneck's car-carrying capacity, in comparison to reserving one of its lanes for buses only. Simulations of a real case study indicate that significant reductions in car delays can result while increasing bus speeds as much as ordinary conversions.

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Section: Bus Priority Strategies Targeted To Linksmentioning

confidence: 99%

Section: Bus Priority Strategies Targeted To Linksmentioning

confidence: 99%

Strategies for sharing bottleneck capacity among buses and cars

Guler

Cassidy

2012

Transportation Research Part B: Methodological

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“…This factor also depends on the number of remaining free lanes: the higher the number of lanes, the smaller the overall effect (i.e., the higher the ). Merging effects and the impact of lane changes have been studied in freeway environments, either with an endogenous model [43][44][45], simulation [46,47], or empirical data [48,49]. In this paper, as it will be later shown, the parameter can be easily calibrated with a simple simulation experiment performed in a controlled manner.…”

Section: Formulationsmentioning

confidence: 99%

Designing Dynamic Delivery Parking Spots in Urban Areas to Reduce Traffic Disruptions

Roca-Riu¹,

Cao²,

Dakic³

et al. 2017

Journal of Advanced Transportation

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Pick-up and delivery services are essential for businesses in urban areas. However, due to the limited space in city centers, it might be unfeasible to provide sufficient loading/unloading spots. As a result, this type of operations often interferes with traffic by occupying road space (e.g., illegal parking). In this study, a potential solution is investigated: Dynamic Delivery Parking Spots (DDPS). With this concept, based on the time-varying traffic demand, the area allowed for delivery parking changes over time in order to maximize delivery opportunities while reducing traffic disruptions. Using the hydrodynamic theory of traffic flow, we analyze the traffic discharging rate on an urban link with DDPS. In comparison to the situation without delivery parking, the results show that although DDPS occupy some space on a driving lane, it is possible to keep the delay at a local level, that is, without spreading to the network. In this paper, we provide a methodology for the DDPS design, so that the delivery requests can be satisfied while their negative impacts on traffic are reduced. A simulation study is used to validate the model and to estimate delay compared to real situations with illegal parking, showing that DDPS can reduce system's delay.

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“…Cassidy et al . revealed smoothing effects, that is, favorable influences of carpool lane on the whole traffic flows. In addition, Patire and Cassidy observed that lane‐changing maneuvers induced by periodical speed disturbances mainly resulted in outflow reductions in uphill freeway segments.…”

Section: Related Workmentioning

confidence: 99%

Investigations of interactions between bus rapid transit and general traffic flows

Chen

Jiang

et al. 2014

J of Advced Transportation

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SUMMARYBus rapid transit (BRT) is a popular strategy to increase transit attraction because of its high-capacity, comfortable service, and fast travel speed with the exclusive right-of-way. Various engineering designs of right-of-way and the violation enforcement influence interactions between BRT and general traffic flows. An empirical assessment framework is proposed to investigate traffic congestion and lane-changing patterns at one typical bottleneck along a BRT corridor. The BRT bottleneck consists of bus lane, BRT station, video enforcement zone, and transit signal priority intersection. We analyze oblique cumulative vehicle counts and oblique cumulative lane-changing maneuvers extracted from videos. The cumulative vehicle counts method widely applied in revealing queueing dynamics at freeway bottlenecks is extended to an urban BRT corridor. In the study site, we assume four lane-changing patterns, three of which are verified by the empirical measurements. Investigations of interactions between buses and general traffic show that abnormal behaviors (such as lane violations and slow moving of the general traffic) induce 16% reduction in the saturation rate of general traffic and 17% increase in bus travel time. Further observations show that the BRT station and its induced increasing lane-changing maneuvers increase the downstream queue discharge flows of general traffic. The empirical results also contribute to more efficient strategies of BRT planning and operations, such as alternative enforcement methods, various lane separation types, and optimized traffic operations.

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The smoothing effect of carpool lanes on freeway bottlenecks

Cited by 23 publications

References 16 publications

Strategies for sharing bottleneck capacity among buses and cars

Strategies for sharing bottleneck capacity among buses and cars

Designing Dynamic Delivery Parking Spots in Urban Areas to Reduce Traffic Disruptions

Investigations of interactions between bus rapid transit and general traffic flows

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