Browsing by Subject "Managed Lanes"
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Item Examining Decision-making Surrounding the Use of Managed Lanes by Katy Freeway Travelers: A Prospect Theory Approach(2014-01-14) Huang, ChaoMost previous research that models travelers' behavior in using managed lanes (MLs) versus a toll-free route has derived the individual?s route-choice decision using a utility maximization approach. More recent models incorporating risk are based on expected utility theory (EUT). However, violations of some key assumptions of the EUT have led to the development of nonexpected utility theories, among which prospect theory (PT) has been one the most widely examined. This study examined if PT is superior to EUT when predicting route/mode choice and understanding travelers? behavior in the case of MLs by embedding PT proposed value function and probability weighting functions in the utility estimation. From both EUT and PT approaches, this study used survey data from 2012 to predict the mode choices that include MLs and toll-free alternatives, and provided estimates of the value that travelers are willing to pay (WTP) for travel time savings on MLs. The responses from the survey were examined using advanced discrete choice modeling techniques. Significant and interesting general findings resemble those in previous studies that use PT, including the fact that individuals weight probabilities. Two survey design methodologies, Db-efficient and adaptive random, were tested in this survey. Estimates from the EUT and PT approaches, as well as from previous studies on Katy Freeway travelers, are compared. The results of this study indicate that Katy Freeway travelers are more risk averse when in a situation of being late for work than they are with potential savings in travel time, and they, on average, demonstrate a sense of optimism when the chances of facing a longer travel time are high. PT based models, particularly the model embedding with probability weighting, outperforms EUT based models in terms of the predicative power. On average, models with probability weighting resulted in more than 65 percent of all mode choices correctly predicted, while conventional EUT models predict about 35 percent of choices correctly among four alternatives. Compared to previously available route choice studies, the relatively low willingness to pay (WTP) measures ($8 to $14/hour) calculated in this study from the PT models may deserve further investigation. Empirical findings from this study would help the policy makers set up appropriate project goals and toll rates to meet the increasing traffic demand of Katy Freeway travelers. The patronage of toll facility and MLs largely depends on the potential benefits (more reliable travel time and/or travel time savings) offered by such a facility. How the travelers actually perceive the potential benefits may have a significant influence on the use of MLs. This is about the belief that the travelers have on the facility. In lieu of the significant improvement in predicative power of the models embedding probability weighting functions and because of the stochastic nature of travel times, in future survey efforts it might be helpful to collect information regarding Katy Freeway travelers? actual belief on the benefits from using the MLs, and compare their ?belief? with the actual probability of reliable travel time and savings. Such comparison might help verify the accuracy of the probability weighting functions obtained in this study.Item Potential use of managed lanes by Texas residents(2009-05-15) Mahlawat, ManeeshTraffic congestion is a serious problem in the United States and is likely to get worse. A number of strategies encompassing increasing supply and managing demand have been suggested to mitigate the problem of traffic congestion. These strategies seek to reduce travel time and/or make travel time more reliable. The use of managed lanes is one such strategy. Faced with successful implementation of a managed lane strategy, it is important to understand potential public perception of the managed lane as well as estimate the number of travelers willing to use managed lanes. Such an estimate would help estimate the toll rates for optimal usage of managed lanes by carpoolers and toll paying travelers. An online survey augmented by paper and laptop survey was conducted in Houston and Dallas to collect information about travelers? travel behavior, socio-economic characteristics, managed lane perception, and potential use of managed lanes. A comparison of interest in using managed lanes revealed that in majority of cases there was no difference in interest in using managed lanes across user groups. Travel time reliability and ability to travel faster were indicated as top two reasons for interest in managed lanes. This was true for all travelers regardless of mode. Mode choice model using multinomial logit modeling were estimated for Houston and Dallas. Simulation studies were conducted using these mode choice models to estimate the percentage of Single Occupant Vehicle (SOV) travelers on managed lane (ML), High Occupancy Vehicle with two travelers (HOV2) on ML, High Occupancy Vehicle with three or more travelers (HOV3+) on ML, SOV travelers on general purpose lane (GPL), HOV2 travelers on GPL, and HOV3+ travelers on GPL. These scenarios compared the managed lane usage for different speeds on GPL (25 miles per hour, 30 miles per hour, and 35 miles per hour). For the case when general purpose lane speed is 25 miles per hour, an increase of $11.75 in SOV tolls ($18 from $6.25) decreases the modal share of SOV travelers on Houston ML from 23.3 percent to 16.9 percent. A similar increase in Dallas tolls decreases the modal share of SOV ML travelers from 22.0 percent to 16.3 percent.Item Reactions to Value Pricing by Different Suburban Population Groups(2011-08-08) Lowery, JohnValue pricing strategies are beginning to be considered for future improvements in suburban areas that currently do not experience significant congestion but are expected to become congested in the future. This is a significant departure from implementing these strategies in congested urban areas as is commonly done now. Therefore, traveler reaction in these suburban areas is unknown. To plan and design value pricing projects most effectively, it will be necessary to gain an understanding of suburban travelers' potential reaction to value pricing. Responses to a survey of travelers using the eastern and western segments of Interstate 10 (I-10) outside of San Antonio were used to study differences in response to value pricing by suburban population groups. These surveys collected information on travelers' socioeconomic and trip characteristics as well as their attitudes towards value pricing in the form of potential Express Toll Lanes (ETLS). Stated preference scenarios presented to survey respondents were used to develop mode choice models. These models were used to determine characteristics that may impact the decision to choose to travel on the general purpose lanes (GPLs) or the ETLs. This research suggests that the implementation of value pricing strategies on suburban corridors may pose a challenge from a policy standpoint. The populations using these corridors appear to be more varied in their responses toward value pricing than populations using congested urban corridors. Overall, it was found that the majority of travelers on I-10E and I-10W are not favorable to the implementation of value pricing for the future expansion of these corridors. However, I-10W travelers seem to be more willing to pay for travel time savings. This is likely due to the fact that travelers on I-10W earn higher average incomes, are more likely to use I-10W on a regular basis for commute purposes, and are more often exposed to some traffic congestion. Conversely, travelers on I-10E are more likely to use I-10E less frequently for non-commute trips, travel longer distances, and probably do not have an intuitive sense of the value they would place on travel time savings since they do not regularly experience congestion.Item Understanding and Estimating the Value Travelers Place on Their Trips on Managed Lanes(2011-02-22) Patil, Sunil N.Travelers' value of travel time savings (VTTS) are often used to estimate the benefits of transportation facilities, including managed lanes (MLs). With various eligibility criteria and time of day pricing on the MLs, the VTTS estimation is complicated. This is evident by the underestimation of VTTS on MLs in many of the previous studies. This study investigates stated preference (SP) survey design strategies and differentiating the VTTS for ordinary and some common urgent situations faced by the travelers in an attempt to improve on VTTS estimation on MLs. This study used three different survey design strategies (including a D-efficient design) in an internet based survey of Katy Freeway travelers. It was found that a random attribute level generation strategy, where the VTTS presented in the alternative was adjusted based on the answer to a previous SP question, performs better than the other two designs with respect to VTTS estimation and other survey design efficiency criteria. The analysis to differentiate the VTTS for ordinary and urgent trips was carried out using the state of art in the mixed logit model estimation. It was found that travelers value their travel time savings much more when facing most of these urgent situations rather than ordinary situations. Both peak and off-peak period travelers' VTTS were also found to be significantly greater when on urgent trips. Survey design attribute level ranges were found to significantly affect the VTTS estimation. Further, in order to understand the policy implications of these findings it was demonstrated that classifying all trips as ordinary can significantly underestimate the VTTS benefits offered by the MLs. Additionally, the VTTS of any urgent trips would be greatly underestimated. The study also demonstrated that many of the low and medium income group travelers on urgent trips can have VTTS greater than that of the highest VTTS traveler from the high income group on an ordinary trip. These findings have significant policy implications since the benefits of MLs (and of most transportation investments) are primarily derived from travel time savings. Underestimating the VTTS and hence the benefits for MLs can result in reducing the likelihood of funding such facilities. This study provides an important first step in the proper estimation of these benefits by suggesting modifications to SP surveys to better capture the influence of urgent trips on the value of a ML facility.Item Understanding the Behavior of Travelers Using Managed Lanes - A Study Using Stated Preference and Revealed Preference Data(2012-12-05) Devarasetty, Prem Chand 1985-This research examined if travelers are paying for travel on managed lanes (MLs) as they indicated that they would in a 2008 survey. The other objectives of this research included estimating travelers? value of travel time savings (VTTS) and their value of travel time reliability (VOR), and examining the multiple survey designs used in a 2008 survey to identify which survey design better predicted ML traveler behavior. To achieve the objectives, an Internet-based follow-up stated preference (SP) survey of Houston?s Katy Freeway travelers was conducted in 2010. Three survey design methodologies?Db-efficient, random level generation, and adaptive random?were tested in this survey. A total of 3,325 responses were gathered from the survey, and of those, 869 responses were from those who likely also responded to the previous 2008 survey. Mixed logit models were developed for those 869 previous survey respondents to estimate and compare the VTTS to the 2008 survey estimates. It was found that the 2008 survey estimates of the VTTS were very close to the 2010 survey estimates. In addition, separate mixed logit models were developed from the responses obtained from the three different design strategies in the 2010 survey. The implied mean VTTS varied across the design-specific models. Only the Db-efficient design was able to estimate a VOR. Based on this and several other metrics, the Db-efficient design outperformed the other designs. A mixed logit model including all the responses from all three designs was also developed; the implied mean VTTS was estimated as 65 percent ($22/hr) of the mean hourly wage rate, and the implied mean VOR was estimated as 108 percent ($37/hr) of the mean hourly wage rate. Data on actual usage of the MLs were also collected. Based on actual usage, the average VTTS was calculated as $51/hr. However, the $51/hr travelers are paying likely also includes the value travelers place on travel time reliability of the MLs. The total (VTTS+VOR) amount estimated from the all-inclusive model from the survey was $59/hr, which is close to the value estimated from the actual usage. The Db-efficient design estimated this total as $50/hr. This research also shows that travelers have a difficulty in estimating the time they save while using a ML. They greatly overestimate the amount of time saved. It may well be that even though travelers are saving a small amount of time they value that time savings (and avoiding congestion) much higher ? possibly similar to their amount of perceived travel time savings. The initial findings from this study, reported here, are consistent with the hypothesis that travelers are paying for their travel on MLs, much as they said that they would in our previous survey. This supports the use of data on intended behavior in policy analysis.