Value Of Travel Time Reliability Research Articles

Implementable Regional Truck Freight Planning Practices: Quick Ways to Get Started

To support the elevation of truck freight within the regional planning process, this study identified seven practices regional planners can initiate: coordinating land planning and truck freight planning; using freight advisory committees; monetizing reliability in project prioritization; quantifying truck parking deficiencies; using engineering strategies; incorporating truck freight into scenario planning; and obtaining freight data from public sources. A review of the literature and agency actions was conducted to identify these practices. Although these practices benefit from regional support, they cannot be fully implemented at the regional level. Some require municipal or county authority: reservation of street space for truck parking, modification of local zoning ordinances to mandate truck parking, and allowance of trucks in lanes reserved for transit in select cities. Some require state authority: allowing trucks to use park and ride lots at night, supporting private sector participation financially in regional freight advisory committees, or using the value of travel time reliability to evaluate freight project benefits. Some require either local or state support: notably, expansion or modification of truck routes based, in part, on examination of truck patterns. All practices carry some type of financial or political cost: one interviewee noted that increased zoning requirements might reduce a locality’s ability to compete for industrial businesses. However, regional staff can start the analysis required to support these practices by identifying the benefits, costs, and feasibility of these initiatives through the regional planning process.

Travel Time Reliability Analysis Considering Bus Bunching: A Case Study in Xi’an, China

Bus bunching occurring at stops has an unstable impact on bus travel time. In order to evaluate urban bus travel time effectively, the travel time reliability (TTR) addressing bus bunching is analyzed. This paper focuses on the delayed time caused by bus bunching in the dwelling process at bus stops and uses the coefficient of variation of time headway to evaluate the degree of bus bunching. Moreover, the travel time deviation (TTD) indicator and travel time on-time accuracy (OTA) model are proposed to evaluate the bus TTR. The proposed model is used to analyze 113 runs of a bus route in Xi’an city, China. Real-time GPS data are used to analyze the operation of each run from the origin to the destination stops. The results show that 74.34% of the runs are delayed. When the value of TTD is higher than |0.1|, 64.2% of runs are delayed with bus bunching. Based on the measuring of OTA in two situations, the value of TTR considering bus bunching is reduced by 20%. In addition, the number of stopping routes at peak periods has a significant impact on the occurrence of bus bunching. The research results would have practical implications for the operation and management of buses.

Stated choices and simulated experiences: Differences in the value of travel time and reliability

Surveys with stated choice experiments (SCE) are widely used to derive values of time and reliability for transport project appraisal purposes. However, such methods ask respondents to make hypothetical choices, which in turn could create a bias between choices made in the experiment compared to those in an environment where the choices have consequence. In this paper, borrowing principles of experimental economics, we introduce an incentive compatible driving simulator experiment, where participants are required to experience the travel time of their chosen route and actually pay any toll costs associated with the choice of a tolled road. In a first for the literature, we use a within respondent design to compare both the value of travel time savings (VTT) and value of travel time reliability (VOR) across a typical SCE and an environment with simulated consequence. Given the importance of VTT and VOR to transport decision making and the difficulty in estimating VOR using revealed preference data, our results are noteworthy and emphasise that more research on this topic is imperative. We provide suggestions on how the results herein may be used in future studies, to potentially reduce hypothetical bias that may be exhibited in SCE.

Valuation of travel time reliability: Considering the traveler's adaptive expectation with an indifference band on daily trip duration

Abstract In this article, we focus on the valuation of travel time reliability that considers the adaptive expectation with an indifference band on daily trip duration. Owing to the learning effect of adaptive expectation, travel time variation relates to the travel time forecast bias but not to the absolute deviation of daily trip duration. Meanwhile, the indifference band toward travel time variation moderates the adaptive expectation formation in daily trip repetition. In this case, travel time reliability follows the discrete probability distribution. We use the rank-dependent utility framework to capture the value of travel time reliability (VOR), in which the probability transformation accommodates the risk attitude toward random trip duration and provides us the subjective probability weight to each potential reliability point. Numerical simulation indicates that the traveler's subjective VOR awareness associates with both learning rate and indifference band in the adaptive expectation on daily trip duration. We also set forth some policy and practice implications of this research in the traffic assignment and network formulation.

Uncovering the influence of commuters’ perception on the reliability ratio

The dominant method for measuring values of travel time savings (VOT), and values of travel time reliability (VOR) is discrete choice modeling. Studies using revealed preference have tended to use travel times measured by devices such as loop detectors, and thus the perception error of travelers has been largely ignored. In this study, the influence of commuters’ perception error is investigated on data collected of commuters recruited from previous research. The subjects’ self-reported travel times from surveys, and the subjects’ travel times measured by GPS devices were collected. The results indicate that the subjects reliability ratio is greater than 1 in the models with self- reported travel times. In contrast, subjects reliability ratio is smaller than 1 in the models with travel times as measured by GPS devices.

Analysing the Impact of Traffic Incidents on the Travel Time Reliability of Freeway High-Occupancy Vehicle Lanes

This study aims to examine the impact of traffic incidents occurring on general purpose lanes (GPLs) on the travel time reliability of high-occupancy vehicle (HOV) lanes on freeways and to evaluate the differences of travel time reliability on GPLs and HOV lanes under the same incident conditions. In this paper, an empirical travel time reliability analysis is conducted using the travel time and incident data collected between 2009 and 2012 on Interstate 5 and Interstate 405 of the Seattle metropolitan area. Three incident types (i.e., shoulder incident, single lane incident, and multiple lane incident) are considered. Two measures, percentile-based indicator and inflow–percentile travel time function, are used. The results suggest that incidents result in lower values of travel time reliability for all the measures. The results also show that multiple lane incident type has the most significant impact on the freeway route travel time reliability, while shoulder incident type has the least impact. Generally, HOV lanes have higher travel time reliability than GPLs under the same incident types. The findings in this study provide useful decision support for transportation agencies to improve travel time reliability on freeways.

Values of Travel Time Reliability Revealed by Toll Road Uses

Values of Travel Time Reliability Revealed by Toll Road Uses

Capturing value of reliability through road pricing in congested traffic under uncertainty

Empirical studies showed that travel time reliability, usually measured by travel time variance, is strongly correlated with travel time itself. Travel time is highly volatile when the demand approaches or exceeds the capacity. Travel time variability is associated with the level of congestion, and could represent additional costs for travelers who prefer punctual arrivals. Although many studies propose to use road pricing as a tool to capture the value of travel time (VOT) savings and to induce better road usage patterns, the role of the value of reliability (VOR) in designing road pricing schemes has rarely been studied. By using road pricing as a tool to spread out the peak demand, traffic management agencies could improve the utility of travelers who prefer punctual arrivals under traffic congestion and stochastic network conditions. Therefore, we could capture the value of travel time reliability using road pricing, which is rarely discussed in the literature. To quantify the value of travel time reliability (or reliability improvement), we need to integrate trip scheduling, endogenous traffic congestion, travel time uncertainty, and pricing strategies in one modeling framework. This paper developed such a model to capture the impact of pricing on various costs components that affect travel choices, and the role of travel time reliability in shaping departure patterns, queuing process, and the choice of optimal pricing. The model also shows the benefits of improving travel time reliability in various ways. Findings from this paper could help to expand the scope of road pricing, and to develop more comprehensive travel demand management schemes.

Capturing Value of Reliability through Road Pricing in Congested Traffic under Uncertainty

Abstract Empirical studies showed that travel time reliability, usually measured by travel time variance, is strongly correlated with travel time itself. Travel time is highly volatile when the demand approaches or exceeds the capacity. Travel time variability is associated with the level of congestion, and could represent additional costs for travelers who prefer punctual arrivals. Although many studies propose to use road pricing as a tool to capture the value of travel time (VOT) savings and to induce better road usage patterns, the role of the value of reliability (VOR) in designing road pricing schemes has rarely been studied. By using road pricing as a tool to spread out the peak demand, traffic management agencies could improve the utility of travelers who prefer punctual arrivals under traffic congestion and stochastic network conditions. Therefore, we could capture the value of travel time reliability using road pricing, which is rarely discussed in the literature. To quantify the value of travel time reliability (or reliability improvement), we need to integrate trip scheduling, endogenous traffic congestion, travel time uncertainty, and pricing strategies in one modeling framework. This paper developed such a model to capture the impact of pricing on various costs components that affect travel choices, and the role of travel time reliability in shaping departure patterns, queuing process, and the choice of optimal pricing. The model also shows the benefits of improving travel time reliability in various ways. Findings from this paper could help to expand the scope of road pricing, and to develop more comprehensive travel demand management schemes.

The Value of Travel Time and Reliability: Empirical Evidence from Katy Freeway

Travelers place value on both time savings and reliability when choosing a route for a trip. The value of travel time (VOT) has long been an integral part of the appraisal of transport projects. Recently, some transport planners have been incorporating the value of travel time reliability (VOR) as well. This research used data generated by automated vehicle identification sensors from Katy Freeway travelers in Houston, Texas, to estimate VOT and VOR based on revealed preferences of these travelers. Lane choice models were developed to examine the factors influencing travelers’ lane choice decisions in different traffic conditions and to estimate their VOT. Models with two independent variables— travel time and toll—resulted in an estimated VOT from $1.96 to $8.06/h for all trips on a monthly basis. The research could not conclude whether the VOR had any impact on travelers’ lane choice decisions. The percentage of managed-lane trips was higher for the those who traveled the whole length of the managed–general-purpose lanes than for those who traveled only a part of the managed–general-purpose lanes. This difference might be the result of easier accessibility at the end of the managed lanes compared with that for midpoints.

Examining methodological issues on combined RP and SP data

Abstract Revealed preference (RP) and stated preference (SP) data have been widely used in transportation studies to understand user's preferences regarding various travel decisions. This paper focuses on investigating the modeling techniques to address various issues associated with pooled estimation using both RP and SP data, such as the scale variances, the user heterogeneity, and the state dependency effect, etc. Various model structures are explored, and the results are compared in terms of the significance level of the key parameters, the model performance, and the implications on the derived values of (Value of travel Time) VOT and (Value Of travel time Reliability) VOR. The model results indicate that when inter-alternative scale parameters are incorporated, the model performance and fit improve significantly, with much more reasonable state dependency factors, while the error components and the standard deviations for the random parameters in Mixed Logit (ML) model lose their influence. It suggests that the inter-alternative scale parameters are able to capture the unobserved heterogeneity across alternatives and individuals and relax the Independence of Irrelevant Alternatives (IIA) of Multinomial Logit (MNL) models. This paper contributes to the literature by adding empirical studies and providing insights on the modeling approaches to handle joined dataset, particularly in the field of examining VOT and VOR based on joint RP and SP survey data.

Urban commuters’ valuation of travel time reliability based on stated preference survey: A case study of Beijing

Regarding travel mode choices, urban commuters always consider not only travel time but also travel time reliability of different modes. In this study, schedule delays were used for measuring travel reliability. The trip scheduling model and binary logit model were used to estimate the value of travel time reliability. First, by considering the impacts of the income level and time constraint, the trip scheduling models were developed. Then, data for model calibration was collected through street-interview survey based on the stated preference (SP) approach. Finally, the model was calibrated using the collected data and the commuters’ value of travel time reliability were estimated. On the basis of the model results, the influence of income level and time constraint on the value of travel time reliability was analyzed. The results revealed that the value of travel time reliability differed significantly for different income and time constraint levels, and transportation modes. The developed models for travel time reliability analysis can be applied to supporting the travel cost analysis in the future.

Valuation of Travel Time Reliability Accommodating Heterogeneity of Route Choice Behaviors

Because travel time reliability and travel time itself are significant to many transportation system users, transportation planners and decision makers should consider travel time reliability as a key performance measure. Values of travel time reliability have most often been determined by estimating route choice models and evaluating the marginal rates of substitution between the costs and travel time variations. However, the most common formulation imposes strong restrictions on taste variations. In this study a route choice model accommodated the observed and unobserved heterogeneity with the mixed logit framework. Stated preference data were assembled to model drivers’ route choice between a tolled highway and an untolled national road in South Korea. The values of travel time and the values of travel time reliability were estimated with this model by the purpose of the trip and the household income level. These results highlight the need to accommodate observed and unobserved heterogeneity within the context of evaluation of the values of travel time and values of travel time reliability. The results also provide policy makers with information about the impacts of policies on different segments of the population such as the pricing of high-occupancy-toll lanes and express lanes.

New values of time and reliability in passenger transport in The Netherlands

We have established new values of time (VOTs) and values of travel time reliability (VORs) for use in cost-benefit analysis (CBA) of transport projects in The Netherlands. This was the first national study in The Netherlands (and one of the first world-wide) to investigate these topics empirically in a joint framework.Stated preference (SP) questionnaires were designed for interviewing travellers, where the hypothetical alternatives were described in terms of travel time, travel costs and travel time reliability, the latter being presented to the respondents in the form of five possible travel times having equal probability.For passenger transport, we first collected interviews using an existing internet panel. Additional data collection recruitment was done by asking travellers at petrol stations/service areas, parking garages, stations, bus stops, airports and ports to participate in the survey. One important conclusion is that the SP survey using members of this internet panel leads to substantially lower VOTs than the SP survey with en-route recruitment, probably because of self-selection bias in the internet panel.We estimated discrete choice models in which the values of time differ between trips with different time and costs levels, different time and costs changes offered in the SP, and different observed characteristics of the respondents (e.g. education, income, age, household composition). By using a panel latent class model, we also account for unobserved differences between respondents in the value of time and for repeated measurements/panel effects. The reference values of time and the reference reliability ratios were estimated on the 2011 sample only, but the effect of time and cost level, time and cost changes offered and socio-economic attributes was estimated on both the 2009 and 2011 samples.

Impact of Traffic Images on Route Choice and the Value of Time Estimates in Stated Preference Surveys

A difficult aspect of the use of stated preference (SP) experiments to predict travel behavior is the proper presentation of attributes and characteristics of hypothetical trips to respondents. With an increase in the number of transportation choices, the task of concisely and accurately communicating trip attributes in the SP setting becomes increasingly more important. Recent attempts to introduce innovative strategies into the SP setting have yielded techniques to summarize trip attributes more efficiently for respondents. One technique is to use images of traffic conditions as a supplemental means to summarize average trip speed, travel time reliability, and degree of congestion. However, little research has been performed to test the effects of the use of traffic images on models of route choice built from this kind of SP data. In this research, an SP setting was developed to measure the influence of images of traffic conditions on SP responses. Pictures of traffic conditions that correlated to average trip speed were either shown to or withheld from a survey population from Austin, Texas, depending on random assignment. A panel-effects, mixed, multinomial logit model was built to estimate the respondent's route choice behavior. Overall, the model parameters discovered no evidence to support the assertion that traffic image presentation had a statistically significant effect on route choice with respect to the value of travel time savings or the value of travel time reliability.

통행시간 신뢰성 가치에 관한 연구

PURPOSES : Benefits for improvement of travel time reliability obtained from construction of new highways should be considered as a major factor in the feasibility study for highway constructions. The purpose of this study is to develop a method of estimation for the value of travel time reliability. METHODS : Highway type (urban/rural highway) and traffic flow type(interrupted/uninterrupted) was considered to estimate he value of travel time reliability. And Double-bounded Dichotomous Choice among Contingent Valuation Method(CVM) was applied to survey the willingness-to-pay of drivers when travel time reliability is improved. Finally the value of travel time reliability was estimated using the results of survey and logit model. The value of travel time reliability was estimated considering travel objectives, time constraint travel and non-time constraint travel. RESULTS: The value of travel time reliability of business trip is higher than that of non-business trip. The value of travel time reliability of time constraint travel is higher than that of non-time constraint travel. The value of travel time reliability in urban area is higher than that in rural area. CONCLUSIONS: It was concluded that the proposed method in this study is more realistic and proper to estimate the value of travel time reliability because it reflects the situations of time constraint travel and non-time constraint travel.

Investigating Changes in Willingness to Pay for Managed-Lane Systems

This paper investigates the hypothesis that willingness to pay for managed lanes (MLs) changes through time in the aftermath of the opening and operation of a facility. Using a quasi-panel of stated preference surveys, the authors found that the estimates of the value of travel time reliability were almost as high as the value of travel time savings in regular travel situations and were almost twice as high in urgent situations 2 years after the opening and operation of MLs. These results indicate that the presentation of reliability information affects the valuation of travel time savings estimated from stated preference surveys.

What do commuters think travel time reliability is worth? Calculating economic value of reducing the frequency and extent of unexpected delays

The measurement of transportation system reliability has become one of the central topics of travel demand studies. A growing literature concerns the measurement of value of travel time reliability which provides a monetary cost of avoiding unpredictable travel time. The goal of this study is to measure commuters’ sensitivities to travel time reliability and their willingness to pay (WTP) to avoid unreliable routes. The preferences are elicited through a pivoted stated preference survey technique. To circumvent the issue of presenting numerical distributions and statistical terms to day-to-day commuters, we use the frequency of delay days as a means of measuring traveler’s sensitivities to travel time reliability. The advantage of using simplified measures to elicit traveler preferences for travel time reliability is that these methods simply compare days with high delay to days with usual travel time. It was found that travelers are not only averse to the amount of unexpected delay but also to the frequency of days with unexpected delays. The paper presents WTP findings for three measures: travel time, frequency embedded travel time, and travel time reliability. The ‘reliability’ increase in WTP for travel time is found to be nearly proportional to the frequency of experiencing unexpected delays. For example, the WTP for mean travel time is calculated at $6.98/h; however, reliability adds $3.27 (about 50 % of $6.98) to avoid unexpected delays ‘5 out of 10 days’. The results of the study would provide valuable inputs to cost-benefit analyses and traffic and revenue studies required for road tolling investment projects.

Value of Travel Time Reliability: Two Alternative Measures

This paper deals with the estimation of the willingness to pay for travel time reliability (VOR). We report on a stated preferences survey and we provide an econometric treatment of the data using a conditional logit model. Estimations are made according to two alternative approaches: The first uses a mean-variance approach and the second uses specific coefficients for the preferences function. Although the two approaches are significantly different, both yield quite similar estimations for the VOR.

The value of travel time and reliability-evidence from a stated preference survey and actual usage

This research examined travel behavior of Managed Lane (ML) users to better understand the value travelers place on travel time savings and travel time reliability. We also highlight the importance of survey design techniques. These objectives were accomplished through a stated preference survey of Houston’s Katy Freeway travelers. Three stated choice experiment survey design techniques were tested in this study: Bayesian (Db) efficient, random level attribute generation, and an adaptive random approach. Mixed logit models were developed from responses using each of those designs. The value of travel time savings (VTTSs) estimates do vary across the design strategies, with the VTTS estimates based on the Db-efficient design being approximately half the estimates from the other two designs. However, among the three design strategies, the value of travel time reliability (VOR) was only significant in the Db-efficient design.The estimated VTTS from actual Katy Freeway usage (as measured using actual tolls paid and travel time saved on the managed lanes) is $51/h. This likely also includes any value that travelers place on travel time reliability. In comparison, our combined estimate of VTTS and VOR based on the SP survey (Db-efficient design) was $50/h, which is remarkably close to the estimate from the actual usage data. Based on our dataset, the Db-efficient design technique proved superior to the other two techniques. Finally, this research also supports the importance of including both travel time and travel time reliability parameters when estimating the willingness to pay for, and therefore benefits derived from, ML travel.