UC Berkeley Center for Future Urban Transport: A Volvo Center of Excellence

Under the right conditions -- serious traffic congestion, a permissive regulatory environment, and frequent and reliable transit services -- rail transit investments can powerfully shape cities and regions. Rail transit’s city‐shaping powers are due to market forces and policy interventions. By enhancing accessibility (the ability of those living, working, or shopping rail near stops to quickly reach desired destinations) rail services increase the value and desirability of properties in and around stations. Market pressures by themselves rarely produce transit oriented development. To leverage private investments in and around stations, pro‐activism and a certain amount of risk‐taking on the part of local governments are often needed. This report includes case studies from several cities, along with a policy lessons summary. Land value impacts and value capture opportunities are described.

This paper considers the optimization of public infrastructure systems, recognizing that these systems serve multiple user classes. Under the guidance of a policy-making body, the analyst chooses both the system design, including its layout and control, and the prices to be charged for the service. The goal of the optimization is to maximize society's welfare recognizing that the system's performance will in general depend on the system's demand, and vice versa. The optimization problem is first formulated in its full complexity. Under defined circumstances, the problem decomposes into three sub-problems that can be solved sequentially. The resulting design is independent of how net user benefits are measured. If the policy-making body does not specify cost or demand targets, and instead assesses benefits by means of consumer surplus then the optimum design is still the solution of a conventional design problem with fixed demand. In this case, however, the demand has to be obtained iteratively using a marginal cost pricing rule.

"Near-side stops" are bus stops located a short distance upstream of a signalized intersection. A bus dwelling at a near-side stop can impede queued cars upstream as they discharge during their green time at the intersection. Added car delays and residual queues can result. All else equal, the closer the stop’s location to the intersection, the greater the potential damage to car traffic. Models for locating these near-side stops to achieve target levels of residual queueing among cars are formulated using kinematic wave theory. This same approach was also used to develop a strategy for further mitigating residual car queues by temporarily detaining some buses from reaching the stop. This bus-holding strategy can be applied selectively, so that the times that held buses depart from the stop are not affected. The strategy therefore will not delay buses over the longer run. Assessments indicate that this holding strategy can significantly reduce instances of car delays and residual queueing, especially for stops that are located very close to their intersections.

This paper investigates the relationship between transit and urban densities in the United States. An analysis of light rail systems finds that a residential density of about 30 people per gross acre near stations is needed to in order to make them among the top 25 percent of rail transit investments in terms of cost effectiveness; for heavy rail systems, the density is 45 people per gross acre. Increasing density around stations would greatly increase ridership, particularly when jobs are located within one-quarter mile of the stations and housing is located within one-half mile. Stakeholders in the small city of Stockton found high levels of density unacceptable, and supported transit improvements, such as bus rapid transit, only when there would be no impact on private vehicle traffic.

Slow speeds in a special-use lane, such as a carpool (HOV) or bus lane, can be due to both high demand for that lane and slow speeds in the adjacent regular-use lane. These dual influences are confirmed from months of data collected from all freeway carpool facilities in the San Francisco Bay Area. Both influences hold for other types of special-use lanes, including bus lanes. New US regulation stipulating that most classes of low-emitting vehicles, or LEVs, be banned from slow-moving carpool lanes. While LEVs invariably constitute only about 1 percent of the freeway traffic demand in the San Francisco Bay Area, forcing some or all of these vehicles to regular-use lanes can significantly add to regular-lane congestion, and that this, in turn, can also be damaging to vehicles that continue to use the carpool lanes. Counterproductive outcomes of this kind are predicted first by applying kinematic wave analysis to a real Bay Area freeway. The site stands to suffer less from the regulation than will others in the region but the site’s people-hours and vehicle-hours traveled during the rush are predicted to each increase by more than 10 percent and that carpool-lane traffic will share in the damages. Real data from the site support these predictions. Further parametric analysis of a hypothetical, but more generic freeway system indicates that these kinds of negative outcomes will be widespread. Constructive ways to amend the new regulation are discussed, as are promising strategies to increase the vehicle speeds in carpool lanes by improving the travel conditions in regular lanes.

The morning commute problem for a single bottleneck is extended to model mode choice in an urban area with time-dependent demand. This extension recognizes that street space is shared by cars and public transit. It is assumed that transit is operated independently of traffic conditions, and that when it is operated it consumes a fixed amount of space. As a first step, a single fixed-capacity bottleneck that can serve both cars and transit is studied. Commuters choose which mode to use and when to travel in order to minimize the generalized cost of their own trip. The transit agency chooses the headway and when to operate. Transit operations reduce the bottleneck’s capacity for cars by a fixed amount. The following results are shown for this type of bottleneck: 1. If the transit agency charges a fixed fare and operates at a given headway, and only when there is demand, then there is a unique user equilibrium. 2. If the transit agency chooses its headway and time of operation for the common good, then there is a unique system optimum. 3. Time-dependent prices exist to achieve system optimum. Finally, it is also shown that results 2 and 3 apply to urban networks.

This study explores possibilities for advancing bus rapid transit (BRT) systems and associated higher density land development in the Central Valley of California. It uses photo-simulations and stakeholder reactions to visual images to gauge public attitudes toward what would be a fairly radical transformation of urban environments in traditionally car-oriented settings.The kinds of transformations that would be needed to economically justify higher quality BRT services will likely require better and more frequent bus as well as amenities in the form of street trees, landscaping, street furniture, improved building facades, bike lanes, and the like. By eliciting views and responses from local stakeholder interests about BRT service design and surrounding development patterns, the work sought to provide a platform for stimulating open public dialogue on factors that could be vital to successful project implementation.

Bus systems are naturally unstable. Without control, the slightest disturbance to bus motion can cause buses to bunch, reducing schedule reliability. Holding strategies can eliminate this instability. However, the conventional schedule-based holding method requires too much slack time, which slows buses. This delays on-board passengers and increases operating costs. This paper studies a family of dynamic holding strategies that use the current state of all buses, as well as a virtual schedule. The virtual schedule is introduced whether the system is run with a published schedule or not. We found that with this control method, which we term general control method, buses can both closely adhere to schedule and maintain regular headways without too much slack. Thus the general control idea is applicable to bus lines with both long and short headways. Although the optimal set of control parameters can be found numerically, a one-parameter version of the control method can be optimized in closed form. This simple method was shown to be near-optimal. To put it in practice, one only needs the arrival times of the current bus and the preceding bus relative to the virtual schedule. This simple method was found to outperform alternative control methods (i.e., require less slack for the same headway variance). While the paper mostly focuses on recurrent small disturbances under quasi-deterministic demand, it also shows that the proposed control method can deal with large disturbances.

Innovative strategies for deploying bus lanes are proposed for field tests in Amman, Jordan. The objective is to reduce delays to buses in the network while minimizing delays to other vehicular traffic. The proposed strategies may be far better options than conventional, static bus lanes, given the test site’s large car demand and low bus frequency. The experiment is designed to be conducted in simple, safe ways, without the need for investment in permanent infrastructure.

Traffic flow theory is used to analyze the spatio-temporal distribution of flow and density on closed loop homogeneous freeways with many ramps, which produce inflows and allow outflows. It is shown that if the on-ramp demand is space-independent then this distribution tends toward uniformity in space if the freeway is either: (i) uncongested; or (ii) congested with queues on its on-ramps and enough inflow to cause the average freeway density to increase with time. In all other cases, including any recovery phase of a rush hour where the freeway's average density declines, the distribution of flow and density quickly becomes uneven. The flow-density deviations from the average are shown to grow exponentially in time and propagate backwards in space with a fixed wave speed. A consequence of this type of instability is that, during recovery, gaps of uncongested traffic will quickly appear in the unevenly congested stream, reducing average flow. This extends the duration of recovery and invariably creates clockwise hysteresis loops on scatter-plots of average system flow vs. density. All these effects are quantified with formulas and verified with simulations.