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% and total late schedule delay by 72% 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%. Analyses of pretrip ATIS user expectations, outcomes, and counterpart outcomes indicated that users' perceptions of ATIS satisfaction are accurate.