James Larkin

TIME MANAGEMENT IMPACTS OF PRETRIP ADVANCED TRAVELER INFORMATION SYSTEMS: FINDINGS FROM A WASHINGTON, D.C., CASE STUDY

Numerous consumer surveys conclude that users of advanced traveler information systems (ATIS) perceive benefits foremost in travel time, followed by benefits of stress reduction and on-time arrival. Efforts by ATIS evaluators to quantify or empirically validate these benefits through field trials have yielded findings in travel time savings that are inconsistent with findings from surveys. It is hypothesized that users of ATIS benefit in the form of time management and not necessarily by reducing in-vehicle travel time. A novel approach (the simulated yoked study) is presented to evaluate the benefits to commuters from regular ATIS use. To demonstrate the simulated yoked study approach and to test the hypothesis, a case study based on travel conditions in Washington, D.C., between August 1, 1999, and October 1, 1999, was conducted. The travel experiences of commuters regularly using pretrip ATIS are simulated and compared with those of similar commuters using no traveler information before or during their commute. Findings from the case study indicate that benefits are significant in terms of on-time reliability but not in terms of the most frequently used measure of ATIS effectiveness, reduction of in-vehicle travel time. On average, regular pretrip ATIS users can reduce late arrivals by 69 percent and total late schedule delay by 72 percent compared with their counterparts. The regional reliability of the pretrip ATIS service, defined as the percentage of trips using pretrip ATIS that have arrival expectations that are met, is estimated at 77 percent. Analyses of pretrip ATIS user expectations, outcomes, and counterpart outcomes indicated that users’ perceptions of ATIS satisfaction are accurate.

MAKING THE MOST OF LIMITED DATA IN EVALUATING ADVANCED TRAVELER INFORMATION SYSTEMS BY EXPERIMENTAL RESAMPLING

Because of high data collection costs, analysts are commonly faced with the problem of limited data in the evaluation of intelligent transportation systems. How reliable are conclusions based on small samples? If limited data are available, how does one maximize their value? These questions were addressed to evaluate the potential benefits of prospective notification-based traveler information services used to deliver pre-trip travel time information to simulated drivers in a Cincinnati, Ohio, case study. In Cincinnati, travel time data were initially available for only 30 weekdays. An analysis that used this small data set indicated that an advanced traveler information system (ATIS) user would reduce disutility by 32% versus a comparable nonuser. However, since trip experiences on 30 weekdays may not characterize the typical experience of a commuter, conclusions drawn from the small sample may not accurately represent a more generalized assessment of the benefits of ATIS. Hence, an analogue of statistical resampling (experimental resampling) was applied to generate a large sample of days over which the effectiveness of ATIS could be evaluated. With experimental resampling, the reduction in disutility for an ATIS user was only 24%. It was concluded that experimental resampling provided a more reliable estimate of the benefit. To validate the claim, a more extensive study used 154 weekdays spanning a year. The validation analysis found that when compared with the small sample of 30 weekdays, the resampled cases were better predictors of the benefits for the large sample of 154 weekdays.

Potential of advanced traveler information system to reduce travel disutility: Assessment in Washington, D.C., Region

A study quantified the potential benefit of a pretrip advanced traveler information system (ATIS) to travelers in the Washington, D.C., region for the commuter objective of consistently on-time arrival. Paired driver commutes were simulated with a 15-month archive of regional travel times from Smar Traveler.com, an Internet provider of real-time data on travel time. One driver used a personalized pretrip notification service in selecting departure time and route, while the paired counterpart maintained a habitual trip departure time and route. The pairs’ trip arrivals were compared to quantify the effects on time management of a prospective notification service prescribing departure time and route. Approximately 25.9 million paired driver trials were modeled across a network of 55 nodes and 150 links, traversing 711.8 mi of roads in the Washington, D.C., metropolitan region. Trips were simulated for arrivals at 15-min intervals between 6:30 a.m. and 6:30 p.m. on workdays from each node to every other node. Overall, regular use of the pretrip ATIS is shown to benefit commuters whose objective is arriving on time. At low levels of ATIS market penetration, routine ATIS use could reduce early arrivals by 56% and late arrivals by 52%. Benefit in vehicle travel time is minimal. By applying a utility function to each trip, it was calculated that ATIS service reduces aggregate travel disutility by 15%. Approximately 67% of trips (origin–destination) derive a net benefit from routine ATIS use, while 40% benefit by more than

Estimating User Costs and Economic Impacts of Roadway Construction in Six Federal Lands Projects

60/year. Benefits are fairly distributed across the year and are generally greatest during the evening peak.

Comparison of Mobility Impacts on Urban Commuting: Broadcast Advisories Versus Advanced Traveler Information Services

The Federal Lands Highway (FLH) Division staff faces myriad challenges when designing roadway construction projects for roads located on federal lands. An increasingly prevalent challenge is considering not only the “hard” costs of a construction project (e.g., labor and materials) but also the “soft” costs of user delay and the economic impacts on roadway users (e.g., residents, visitors, staff, and local businesses). These soft costs affect every roadway construction project but rarely are considered in design and operation because they often are difficult to estimate and justify. FHWAs 1998 report Meeting the Customers Needs for Mobility and Safety During Construction and Maintenance Operations identifies this issue and recommends that engineers begin to address it, for small- as well as large-scale projects. As part of its responsibility to promote the development and deployment of applied research, FLH staff initiated the development of FLH-QuickZone to help estimate these soft costs of roadway construction. As part of its development, FLH-QuickZone was tested and prototyped in six FLH construction projects: three in national parks, two on forest highways, and one in a national recreation area. Where FLH-QuickZone fits in a spectrum of other estimation tools for work zone delay and how it was used in the six FLH roadway construction projects are summarized. Observations about the challenge of addressing the soft cost of roadway construction projects–with FLH-QuickZone or other analytical tools–also are presented.

Rapid nationwide congestion monitoring: the urban congestion reporting program

This paper explores the effectiveness of relying on commercial radio as a source of traveler information and presents an approach to quantify mobility benefits from radio traffic advisories. The study, conducted for the Washington, D.C., metropolitan area, used an analytical technique called the heuristic online web-linked arrival time estimator to examine whether broadcast traffic advisories could have mobility benefits similar to a prospective notification-based traveler information service offering personalized estimates of travel times. Traffic reports were recorded from a local radio station and manually coded to translate them into a suitable format for analysis. Results from the analysis of 37 weekdays consisting of 4,410 advisories indicated that radio traffic advisories were less effective in improving traveler on-time reliability or reducing travel disutility than a service offering route-specific travel time reports. The simulated commuter receiving regular quantitative estimates of travel times on relevant roadways typically made more effective route and trip-timing decisions than the simulated commuter receiving comparatively incomplete, irregular, and vague advisories on prevailing congestion conditions from broadcast traffic reports. In contrast, the simulated commuter listening to radio advisories recorded similar benefits to those of the simulated control subject, who ignored all forms of traveler information. During the morning peak period, the simulated radio listener fared worse than the simulated control subject and recorded lower on-time reliability performance and higher travel disutility. During the afternoon peak period, the simulated radio listener had lower travel disutility but also experienced a nominal reduction in on-time reliability performance.

Seattle Metropolitan Model Deployment Initiative Evaluation: Results and Key Findings from Modeling

In order to meet a federal request for monthly nationwide congestion monitoring and reporting capability, the Urban Congestion Reporting (UCR) program was developed - an effort that acquires and analyzes travel time data provided by advanced traveler information systems (ATIS) across the nation. Ten cities are now included in monthly reports that refine travel time data into three key regional congestion measures: hours of congested travel (temporal duration of congestion), travel time index (measuring the intensity of delay under congested conditions), and buffer index (a measure of day-to-day travel time variability). Data acquisition and analysis have been successfully automated to meet the FHWA goal of having draft monthly reports issued within 10 working days from the close of the month under analysis. This rapid analysis and reporting program has provided FHWA with a significant new capability to augment its established congestion monitoring program.

ITS impacts assessment for Seattle MMDI evaluation : modeling methodology and results

At the request of the Joint Program Office for intelligent transportation systems (ITS) of the FHWA, Mitretek Systems conducted a modeling analysis of ITS impacts in support of the metropolitan model deployment initiative evaluation program. The Mitretek modeling study supports the evaluation of the Seattle model deployment Smart Trek, testing a series of hypotheses that could not be addressed in controlled field studies or survey research. Using both a regional planning model and a subarea simulation, the study includes a series of experiments to quantify impacts from integrating ITS technologies and services both across jurisdictions and between functional components. The analysis addressed (a) subarea-wide impacts of traffic signal coordination on major arterials, (b) the impact of integrating arterial data into the current freeway-based advanced traveler information service (ATIS), and (c) interactions at the corridor and the regional levels from concurrent deployment of signal coordination and the enhanced freeway and arterial ATIS. Results from that study have been summarized, detailing findings for a 300-km2 mixed freeway and arterial subarea network drawn from the roadway system north of downtown Seattle. The coordination of traffic signals along two major arterials resulted in a 7 percent reduction in overall subarea delay and a 3 percent reduction in total stops. More efficient route diversions for ATIS users result from the integration of arterial data into the current web-based service. At currently estimated levels of ATIS usage (6 percent of travelers), this improved diversion efficiency reduces overall subarea delay (users and nonusers) by over 3 percent.