published journal article
conference paper
Development of advanced technologies for real-time road traffic congestion detection is required by advanced traffic management systems (ATMS) and advanced traveler information systems (ATIS). However, provision of dynamic intra-lane and inter-lane traffic information such as queuing and lane-changing remains incomplete in emerging technologies. This paper is intended to introduce a prototype of a new framework capable of real-time detection of incident and non-incident congestion on freeways. It employs dynamic estimates of lane traffic characteristics including queue lengths in blocked lanes tin the case of lane-blocking incidents), the number of vehicle in each lane, and mandatory lane-changing fractions in lanes with traffic congestion for the use of real-time road traffic congestion detection. On-line lane traffic count and occupancy data collected from point detectors are used as the major input to the proposed framework. The framework is founded on the basis of 1) nonlinear stochastic system modeling and estimation which involves the use of an extended Kalman filter and 2) the modified sequential probability ratio test technology (MSPRT). Preliminary tests had been conducted, indicating the feasibility of employing the proposed framework for the use in real-time incident detection on freeways. Further tasks will include tests for the case of non-incident congestion. The research presented here may help stimulate research in related areas such as incident management systems, automatic vehicle tracking and monitoring systems, and automatic road congestion warning systems for further use in ATMS and ATIS.
working paper
The growth of the Internet has rekindled interest in the relationship between communications and travel. New communication technologies have expanded the range, the type, and the number of transactions that can take place without travel. A number of promotions capture the new tradeoffs between communications and travel: initially, the Internet was referred to as “the information superhighway” and Microsoft ran an ad campaign dubbed “where do you want to go today?” The connection between travel and bytes has been summed up as “The Death of Distance” (Cairncross, 1997). A parallel evolution in telecommunication and transportation was envisioned more than 150 years ago with the inventions of the telegraph and telephone. The telephone was expected to “speed the movement of perishable goods,” “reduce the travels of salesmen,” and “let (itinerant) workers stay at home to be phoned for jobs” (Pool, 1983). Today, the Internet has fueled similar expectations, and many of them center on travelrelated issues. The Internet might relieve demand for new road capacity, slow down the rate of new vehicle ownership, and divert existing travel trips to less congested times. The Internet might help create more sustainable growth in transportation, by providing virtual accessibility. In this paper, we explore the transportation aspects of consumer electronic commerce (e-commerce). Shopping activities are currently automobileintensive in many countries, and increases in e-commerce could portend important changes in transportation patterns and activities.
published journal article
policy brief
Drayage trucks (i.e., heavy-duty trucks that move containers and bulk freight between ports and rail facilities, distribution centers, and other nearby locations) are a critical part of port operations, however, they also adversely affect air quality. In California, drayage fleets are facing strict regulatory pressure under the Advanced Clean Fleets (ACF) regulations. Starting in January 2024, all newly registered drayage trucks in the CARB Online System must be zero emission vehicles (ZEVs), so either a battery electric truck (BET) or hydrogen fuel cell electric truck (HFCET). By 2035, every drayage truck operating in California must be zero-emission. To successfully meet this policy goal, it is important to understand the viewpoints of drayage fleet operators. However, there is limited knowledge about how fleets of various sizes, especially small fleets with 20 or fewer vehicles (which make up 70% of the sector), are responding to ZEVs and related policies. To bridge this gap, the study team surveyed both small and large drayage fleet operators at the Ports of Los Angeles and Long Beach, with 71 companies participating. As part of the survey, fleet operators were asked to choose a preferred truck under different scenarios. In the first scenario, they chose between different ZEV trucks; in the second scenario, they chose between ZEVs, diesel, or natural gas trucks, shedding light on potential reasons which fleets might delay ZEV adoption if they still prefer diesel or natural gas trucks. The team analyzed around 650 choice observations using statistical models to explore these preferences, as well as other survey items regarding their perceptions.
conference paper |
Jan 2025
policy brief
California is committed to transitioning heavy-duty vehicles (HDVs) from diesel to zero-emission vehicles (ZEVs) like battery electric vehicles (BEVs) or hydrogen fuel cell electric vehicles (HFCEVs) by 2045, and in certain cases much sooner. Achieving this goal requires substantial efforts from various sectors, including vehicle manufacturers, infrastructure developers, and governments. It is particularly important to understand the perspectives of HDV fleet operators, as their viewpoints and willingness to adopt ZEVs will be critical to California’s success in this transition. To better understand the perspective of fleet operators, we conducted in-depth interviews with 18 California HDV fleet operators, across various sectors and fleet sizes, on the viability of zero-emission fuels and vehicles over the next 10 to 20 years and the main motivators for, and barriers to, procuring ZEVs.
conference paper |
Jan 2025
published journal article |
Apr 2024
working paper
This paper presents results of an application of the case study approach to the evaluation of alternate TSM strategies. The procedure is useful in the classification of potential sites relative to their expected performance following implementation of specific TSM strategies designed to improve flow conditions. The specific focus of the paper is on the use of classification analysis as a means of transferring analysis results drawing from a small number of representative case studies to a broader range of alternate applications. This approach is shown to provide a reasonable and less costly alternative to individual site-by-site analyses.
published journal article
research report
In this research, a promising ITS-ready microscopic traffic simulator, Paramics1.5, is thoroughlyevaluated both subjectively and objectively in preparation for its use for modeling ITS in SouthernCalifornia. A general and comprehensive list of requirements (evaluation template) for amicroscopic traffic flow simulator to successfully model ITS was first compiled and presented. Theevaluation template covered various aspects of modern transportation network modeling, including:[1] supply/control aspects, [2] demand/behavior aspects, [3] environmental-related aspects, and [4]simulator-performance aspects. The template was applied to Paramics1.5, a new and potentiallysuccessful ITS-oriented micro-simulator. The evaluation revealed Paramics1.5’s capabilities andlimitations as an ITS modeling tool. It was concluded that Paramics1.5 is an excellent ‘shell’ or‘framework’ for a comprehensive and extensive transportation simulation laboratory. Paramics1.5offers two very important and unprecedented features: high performance and scalability. To ourknowledge, this is the most promising approach to handle realistic real word traffic networks underITS. Also, Paramics1.5 offers very plausible detailed modeling for many components of theenvisioned ‘ideal’ simulator. Nevertheless, several limitations were also identified and discussed.Suggestions for improvements were also presented. Improving such limitations requires both directmodifications in the software itself, and maturation of the Application Programming Interface(API), one of Paramics1.5’ most important capabilities. The subjective evaluation was also followedby an objective evaluation based calibration of key driving-behavior parameters underlying -amongother things- the car following and lane changing models of the simulator.Calibration wasconducted using real traffic data from the California Testbed, headquartered at the University ofCalifornia Irvine. The calibrated model performed well during validation on a freeway link. On afull network, the vehicle release mechanism showed some time-lag in releasing demand onto thenetwork. This is potentially due to stacking of vehicles in memory before adequate headways arefound on the road to release the vehicles. Although the problem itself is simple, its effects on theresults were notable.
white paper
This white paper examines the successes and failures of road pricing strategies in California and the United States, with implications for congestion pricing across California. It evaluates nine case studies spanning feasibility studies, operational HOT lane programs, and the country’s first large-scale cordon pricing zone. The research team addresses the conditions that favor pricing, barriers, outcomes, and how costs and benefits are distributed using case studies in Los Angeles, San Diego, San Francisco, San Mateo County, Alameda County, New York City, and Northern Virginia. The research finds that successful pricing programs have sustained political champions, state enabling legislation, and benefits visible to identifiable users. Revenue allocation, not toll structure, is the primary determinant of whether pricing is regressive or progressive. No pricing program reviewed was repealed after implementation. The research team concludes that advancing road pricing in California will require clear state leadership and supportive coalitions.