On incentives and optimal effort to improve bus transit performance

ABSTRACT

This paper studies incentive-based subsidy to transit systems to improve performance. It derives a formula for optimal effort that equalizes marginal cost and marginal benefit and derives some principles from it among which is that the larger the value of a transit system’s performance criterion the larger the effort it will exert to improve it. Next, using a constrained cost minimization approach it derives a nonlinear cost function that includes optimal effort and estimates it using an unbalanced panel data of single mode U.S. bus transit systems. The results show that optimal effort is the equivalent of seven full-time employees (15,243 labor hours) per year and in real terms it results in 0.6% cost saving (US$198,331) and US$836,796 in incentive subsidy per observation. The implications of these findings are examined.     

Freight generation and geographical effects: modelling freight needs of establishments in developing economies and analyzing their geographical disparities

Transportation - Freight generation (FG) models are important to transportation authorities and planning agencies as they can be used to forecast local/regional/state/national freight movements for...     

On the beaten track: a view of US West-Coast container port competition

More than a century ago far-sighted railroad builders and steamship operators were seeking the shortest intermodal itineraries between the eastern United States and the Orient. A combination of locational fact and the factual outcomes of 19th century railroad building left Chicago roughly equidistant in railway mileage from what became the four great US West-Coast port complexes in the Los Angeles, San Francisco, Portland and Seattle regions. Their nearly equivalent rail access to Chicago and points east has renewed significance in the container era.

This paper concerns the efforts of US Pacific seaboard ports to stay 'on the beaten track' with respect to container shipments between Asia and the eastern United States. The West-Coast ports are transit points dividing the transcontinental and transoceanic segments of long intercontinental journeys. From origins to destinations there are, in fact, many possibly feasible itineraries, including all-water routes.

The West-Coast ports have considerable control over their own site improvements. On the other hand, with respect to transiting container traffic, the ports may influence, but are unlikely to control, their own situations. Since the major container port facilities are very often on long-term lease to large intermodal carriers, the latter are making the important shipping and routeing decisions. The carriers tend in fact to set the tone and level of port competition.

What is the nature of the competition between container ports? Is it a figment of the publicist's imagination and perpetuated by irrelevant statistical boasting? Is it perhaps something forced on the ports by carriers eager to play one port off against another in a 'lowest bid' game? At what geographical scale might port competition be most useful or, maybe, least wasteful?     

Impact of high occupancy vehicle lanes on carpooling behavior

High occupancy vehicle lanes have become an integral part of regional transportation planning. Their purpose is to increase ridesharing by offering a travel time advantage to multiple occupant vehicles. This paper examines the extent to which an HOV facility increases ridesharing. Using data from the Route 55 HOV facility in Orange Country, California, changes in the carpooling rate on Route 55 are compared to that of a control group of freeway commuters. The analysis shows that the carpooling rate among peak period commuters, and particularly those who use the entire length of the facility, has increased. However, there has been no significant increase in ridesharing among the entire population of Route 55 commuters. Results suggest that barriers to increased ridesharing are formidable, that travel time savings must be large in order to attract new carpoolers, and that further increases in capooling will likely require development of extensive HOV lane systems.     

A simulation‐based reliability assessment approach for congested transit network

This paper is an attempt to develop a generic simulation‐based approach to assess transit service reliability, taking into account interaction between network performance and passengers' route choice behaviour. Three types of reliability, say, system wide travel time reliability, schedule reliability and direct boarding waiting‐time reliability are defined from perspectives of the community or transit administration, the operator and passengers. A Monte Carlo simulation approach with a stochastic user equilibrium transit assignment model embedded is proposed to quantify these three reliability measures of transit service. A simple transit network with a bus rapid transit (BRT) corridor is analysed as a case study where the impacts of BRT components on transit service reliability are evaluated preliminarily.     

A comparison of two methodologies for selecting transit performance indicators

Two contrasting methodologies have appeared in the literature for selecting indicators to evaluate the performance of public transit firms. One methodology specifies the criteria that the selected performance indicators must satisfy. The other methodology requires the specification of operating objectives by the transit firm for the purpose of then selecting performance indicators. This paper compares the two methodologies and discusses the attributes of one methodology versus those of the other methodology. Also, a major difference in the premises of the two methodologies is demonstrated.     

Optimal slack time for timed transfers at a transit terminal

At transit terminals where two routes interchange passengers, total system costs may be reduced by allowing some “slack” time in the vehicle schedules to decrease the probability of missed connections. Transfer cost functions are formulated and used to determine optimal slack time for simple systems with transfers between one bus route and one rail line. Some analytic results are derived for empirical discrete and Gumbel distributions of bus arrival times. Relations between the optimal slack times and headways, transfer volumes, passenger time values, bus operating costs, and standard deviations of bus and train arrivals are also developed numerically using normally distributed arrivals. However, the proposed numerical approach can optimize slack times for any observed arrival distributions. The results provide some guidelines on desirable slack times and show that schedule coordination between the two routes is not worth attempting when standard deviations of arrivals exceed certain levels. Possible extensions of this work are suggested in the last section.     

Real-Time Fuzzy Obstacle Avoidance Using Directional Visual Perception

This paper presents a novel vision-based obstacle avoidance approach for the Autonomous Mobile Robot (AMR) with a PanTilt-Zoom (PTZ) camera as its only sensing modality. The approach combines the morphological closing operation based on Sobel Edge Detection Operation and the (μ-kσ) thresholding technique to detect obstacles to soften the various lighting and ground floor effects. Both the morphology method and thresholding technique are computationaUy simple. The processing speed of the algorithm is fast enough to avoid some active obstacles. In addition, this approach takes into account the history obstacle effects on the current state. Fuzzy logic is used to control the behaviors of AMR as it navigates in the environment. All behaviors run concurrendy and generate motor response solely based on vision perception. A priority based on subsumption coordinator selects the most appropriate response to direct the AMR away from obstacles. Validation of the proposed approach is done on a Pioneer 1 mobile robot.     

Grade measurement with an instrumented car

Grade information may be needed for route surveys and is important when fuel consumption is studied. An instrumented car was used to measure acceleration along the road surface by double differentiating accumulated pulses generated off the drive train. A second acceleration measure included the component due to gravity relative to the car body. The difference between these acceleration measures contains grade information but it also influenced by suspension dynamics and pitch of the car body. The effect of suspension dynamics was removed by filtering which limited the minimum wavelength to 160 m. The effect of pitch was removed by a correction based on acceleration, jerk and the square of vehicle speed. The correction was computed from data collected on a level airfield runaway. The method is verified for a high capacity arterial road. Grade is measured to within 0.001 rad (95% confidence limits). Elevation derived from the grade data was consistent with road construction drawings to the same limits.