High-occupancy/toll lanes: where should they be implemented?

Real data show that reserving a lane for carpools on congested freeways induces a smoothing effect that is characterized by significantly higher bottleneck discharge flows (capacities) in adjacent lanes. The effect arises because disruptive vehicle lane changing diminishes in the presence of a carpool lane. The effect is reproducible across days and freeway sites: it was observed, without exception, in all cases tested.Queueing analysis shows that the effect greatly reduces the times spent by people and vehicles in queues. By ignoring the smoothing effect at one of the sites we analyzed, for example, one would predict that its carpool lane increased both the people-hours and the vehicle-hours traveled by well over 300%; when in reality the carpool lane and its attendant smoothing reduced both measures. The effect is so significant, in fact, that even a severely underused carpool lane can in some instances increase a freeway bottleneck's total discharge flow. This happens for the site we analyzed when carpool demand is as low as 1200 vph. It follows that strategies designed to induce smoothing by other means also hold promise for managing congestion, both for freeways that have carpool lanes and those that do not. Possible strategies of this kind are discussed.

show abstract

“…Let us now see what a conventional analysis (wrongly ignoring the smoothing effect) as in Dahlgren (1998Dahlgren ( , 2002 and Kirshner (2001) …”

Section: The Real Impacts Of Carpool Lanes On People and Vehicle Delaymentioning

confidence: 99%

The smoothing effect of carpool lanes on freeway bottlenecks

Cassidy

Jang

Daganzo

2010

Transportation Research Part A: Policy and Practice

View full text Add to dashboard Cite

show abstract

“…Road pricing can also take the form of 'value pricing' in which travellers can choose between a free but congested roadway and a priced roadway. High-occupancy toll (HOT) lanes for instance − mainly present in American urban areas − offer an uncongested roadway to people who are willing to pay a time-varying toll (or ride in carpools) on an otherwise free and congested road (Brownstone and Small, 2005;Dahlgren, 2002;Small and Yan, 2001;Sullivan, 2002). People attaching a lot of value to reducing travel time (i.e., people having a high value of time (VOT); mostly related with high incomes) might be more inclined to pay for an uncongested roadway compared to others.…”

Section: Introductionmentioning

confidence: 99%

Road pricing in a polycentric urban region: Analysing a pilot project in Belgium

Vos

2016

Transport Policy

View full text Add to dashboard Cite

In order to cope with growing car use and congestion, academics often suggest road pricing as a way to reduce car use and internalise external costs (such as congestion and air pollution). However, implementations of road pricing schemes are rather limited and mainly focus on large cities (i.e., cordon charges). Recently, the three regional governments of Belgium − a highly urbanised and polycentric country -have commissioned a pilot project of an area-wide, time-and locationdifferentiated road pricing scheme, hence differentiating charges according to the time of the day and the type of road used. Results of this project indicate that kilometres travelled by car mainly reduce in urban areas, while car use on motorways only reduces to a limited degree. Furthermore, results indicate that urban residents adapt their travel behaviour more than suburban and rural residents, probably because urban dwellers have more alternatives to travel than driving personal cars only, especially on the short run. In this paper, we will analyse the preliminary outcomes of the conducted pilot project, look into the limitations of this project and suggest an alternative road pricing scheme.

show abstract

“…At the same time, in some areas, the knowledge that especially certain segments of car drivers have high valuations of travel time savings has been exploited by allowing single occupancy vehicle drivers to pay a toll for using HOV lanes, turning them into high occupancy toll (HOT) lanes (see e.g. Li, 2001;Dahlgren, 2002). The present paper presents a novel application in this context, looking at allowing drivers to pay a toll for using a dedicated express bus lane on the New Jeresy approach roadway to the Lincoln Tunnel for priority access to New York City.…”

Section: Introductionmentioning

confidence: 99%