Edward Sullivan

STATE ROUTE 91 VALUE-PRICED EXPRESS LANES: UPDATED OBSERVATIONS

Recently over 5 years of field observations were concluded of the valuepriced express lanes that opened December 27, 1995, in the median of State Route 91, in Orange County, California. Data collection, covering about a year and a half of observations to establish baseline conditions before opening day, included traffic measurements, vehicle occupancy counts, transit ridership, and comprehensive travel surveys of current and former commuters. The corresponding data analysis included the calibration of choice models of route, occupancy, transponder acquisition, and time-of-day behavior of commuters and the estimation of air pollution emissions. Findings are presented on traffic trends, toll lane use, travelers’ responses to changing congestion and tolls, shifts in ridesharing and transit use, shifts in trip purpose, differences associated with income and other demographics, public opinion, collision experience, and the results of choice and emissions modeling. As the first practical application of value pricing in the United States, the State Route 91 express lanes provide many important insights, both technical and institutional, some of which are relevant to the implementation of value-pricing projects in other locations.

Commuter behavior on California State Route 91 after introducing variable-toll express lanes

In December 1995, four new variable-toll express lanes were added to the median of a 16-km segment of California State Route 91 (SR-91). For those willing to pay the tolls, the new lanes provide an option to bypass congestion on the regular lanes. A special provision has initially allowed three-plus occupant vehicles to travel the congestion-free facility free of charge. A telephone survey of SR-91 travelers taken in fall 1996 provides insight as to how peak-period, peak-direction work commuters have responded to the new express lanes. Responses of 324 interviewed commuters are analyzed for changes in ridesharing, trends in express lane use, and differences in travel behavior among various socioeconomic groups. This research is important because public concern about fairness is a significant obstacle to the implementation of lane pricing. Two approaches are used to analyze changes in ridesharing and express lane usage. One approach focuses on usual travel behavior; the other focuses on the most recent work trip. The results of both approaches suggest that there has been an overall shift by commuters from lower to higher occupancy vehicles since the opening of the express lanes, and that express lane usage increases as the per person modal cost decreases. An aggregate analysis indicates that 23 percent of SR-91 commuters use the express lane for most of their work trips, and 46 percent never use the lanes. Statistical tests indicate that among two-occupant-vehicle commuters, household income influences express lane usage, and that among single-occupant-vehicle commuters, household type influences express lane usage.

Investigation of Median Trees and Collisions on Urban and Suburban Conventional Highways in California

This study examines safety in the presence of large trees in curbed medians of conventional highways that are also principal streets in developed urban and suburban areas. Statistical modeling methods were used to associate collision frequency and severity with highway and traffic characteristics, with and without median trees. The methods include simple accident rates and three types of multivariate modeling and use collision data for 6 years. The analysis was done in two parts. The first part was a screening investigation of pertinent facilities under both state and local jurisdiction. The second part, described here in detail, focused on 14,283 collisions occurring on 58 mi (99 km) of designated state highways in 29 different sections, 19 with median trees. The analysis examined different subsets of reported collisions, in turn omitting collisions on the right side of the road, collisions not having median or median-shoulder involvement, and collisions at intersections. The overall conclusion is that large trees in medians of major conventional urban and suburban highways of state jurisdiction are associated with more collisions and increased severity. However, some of these associations are statistically weak. For the situations examined, lower speeds and larger side clearances were not found to mitigate the increased collision impacts associated with median trees.

Traffic Video Image Processing Systems Installations - An Examination of VIPS Standardization

During two recent research projects (1993-94 and 1996-97), the California Polytechnic State University - San Luis Obispo (Cal Poly) and the California Department of Transportation (Caltrans) conducted field tests in a variety of freeway/highway/street locations and under a variety of conditions to assess the feasibility of deployment of traffic video image processing systems (VIPS) for detection purposes in California. This paper discusses system performance issues as well as some of the major needs for standardization in the area of traffic detection through image processing as observed during the field tests for both freeway monitoring as well as intersection control.

Industrial Strength Changes in Engineering Education

The triangle of government, industry and education is one of the cornerstones defining the technology evolution patterns of society (and more). Within that triangle, innumerable interactions with continuous feedback processes create an overall picture that is frequently too complicated to paint in a single dimension. One problem addressed from time to time is that of how closely aligned the objectives of industry and engineering education should be. The short-term benefits of having industry dictate engineering education objectives can easily be observed. Long-term issues and results are more difficult to anticipate, but should be given equal consideration. This paper examines some of the trends and needs in view of new interaction tools that have become available over the past two decades. A case study of recent changes at California Polytechnic State University – the flagship of the California State University system – exemplifies the status quo for California on this topic. Overall, the authors take a dim view of the current situation. The intention is to provide a sceptical review of ‘what can go wrong’ – a question that some engineers cannot remove from their minds. Major reflection points include the effort to fit more into a smaller (unit and time) bag; the messages that academics are receiving about success and failure; the fluctuations in student demand; and, last but not least, the overall ‘educational’ experience of the students.

Case Study: Impacts of Advanced Technology on a Small City Bus System

SLO Transit was chosen by Caltrans to demonstrate low-cost Advanced Public Transportation System (APTS) technologies designed specifically for small transit systems. Mobile data terminals with GPS locators were installed on all vehicles, with real-time bus location and emergency alarm data transmitted via radio modems using previously existing voice radios. Besides providing useful data for system planning, the real-time bus location data are used to advise drivers regarding schedule adherence and to generate messages regarding impending bus arrivals employing Smart Transit Signs at principal bus stops throughout town.

Assessing Traffic and User Impacts for the California Route 91 Variable-Toll Express Lane Facility

Abstract The fifteen kilometer long variable-toll express lanes on State Route 91 (SR 91) in Orange County, California, entered revenue service in late December 1995. The new toll lanes, located in the median of the existing freeway, are the first practical implementation of congestion-based pricing in the United States. Caltrans and the U.S. Department of Transportation are sponsoring research to understand travelers’ reactions to congestion-based tolls and to the other innovative features of the new toll lanes. This paper describes the SR 91 project presents some initial findings of the assessment research, and discusses implications for the future of congestion-based toll highways elsewhere in the United States.