Understanding the Behavior of Travelers Using Managed Lanes

Understanding the Behavior of Travelers Using Managed Lanes
Author: Prem Chand Devarasetty
Publisher:
Total Pages: 168
Release: 2013
Genre:
ISBN:

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. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/148178

Examining Decision-making Surrounding the Use of Managed Lanes by Katy Freeway Travelers

Examining Decision-making Surrounding the Use of Managed Lanes by Katy Freeway Travelers
Author: Chao Huang
Publisher:
Total Pages:
Release: 2015
Genre:
ISBN:

Most 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. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/152505

Potential Use of Managed Lanes by Texas Residents

Potential Use of Managed Lanes by Texas Residents
Author: Maneesh Mahlawat
Publisher:
Total Pages:
Release: 2010
Genre:
ISBN:

Traffic 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 travelers0́9 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.

The Influence of Psychological Characteristics on Managed Lane Use

The Influence of Psychological Characteristics on Managed Lane Use
Author: Lisa Larsen Green
Publisher:
Total Pages:
Release: 2015
Genre:
ISBN:

As managed lane (ML) prevalence increases in the United States of America, it is important to understand travel behavior in ML settings (i.e., lane choices and carpooling decisions). Socio-demographic and trip data, along with travel time and toll, have been commonly used in this endeavor. However, there are some travelers who pay to use the ML despite there being little to no improvement in travel time over the adjacent general purpose lanes (GPLs). This gives rise to the possibility that psychological traits are a greater influence on ML use than even travel time savings for some travelers. This research examined this issue through a set of largely transportation-framed psychological items. After an initial creation and refining process, 25 psychological items were included in a survey advertised in five ML study areas (Seattle, Salt Lake City (SLC), Los Angeles, Washington, D.C. (DC), and Minneapolis (Minn)). D[subscript b]-efficient (DBE) and adaptive random (AR) designs were used to develop the attribute levels for the stated preference (SP) questions. The DBE design resulted in a higher adjusted rho square value and a higher overall percent correctly predicted value for a given model than the AR design; however, the AR design resulted in a higher carpool express lane (CP-EL) alternative percent correctly predicted value for a given model, and less non-trading and lexicographic behavior. In addition to psychological items, trip and demographic questions, and three SP questions were included in the online survey. Based on mixed logit models created from responses obtained from SLC, Minn, and DC, better models (in terms of adjusted rho squared value and percent correctly predicted values) were obtained via the creation of psychological item models, when compared to their psychological scale or trip and demographic model counterparts. Likewise, combined models involving psychological items and trip and/or demographic data performed even better. This information may be useful for traffic and revenue estimating firms interested in potentially including psychological items in future ML surveys intended to facilitate better estimation of ML use. Those who agree that "the coordination involved with carpooling is more hassle than it is worth" had a lower likelihood of selecting the carpool on the general purpose lane (CP-GPL) alternative than the drive alone on the general purpose (DA-GPL) alternative. Likewise, they had a lower likelihood of selecting the CP-EL alternative than the DA-GPL alternative. The same results were found for those who "do not like relying on others for rides." Those who agreed that "Unless there is no traffic on the freeway, I choose the express lane since traffic could become congested at any time" had a higher likelihood of selecting the drive alone on the express lane (DA-EL) alternative than the DA-GPL alternative. Respondents who said that "When buying fuel for my car, I use the most convenient gas station and do not pay much attention to price" had a higher likelihood of selecting the DA-GPL alternative than the CP-EL alternative, and had a higher likelihood of selecting the DA-EL alternative than the DA-GPL alternative. The opposite was found for those who "cannot understand why someone would pay to use the express lanes when the general purpose lanes are available for free, especially when it may or may not save time". Those who indicated that "I only choose to use the express lane if the general purpose lanes seem crowded" had a lower likelihood of selecting the DA-EL alternative than the DA-GPL alternative. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/155537

Dynamic Pricing and Long-term Planning Models for Managed Lanes with Multiple Entrances and Exits

Dynamic Pricing and Long-term Planning Models for Managed Lanes with Multiple Entrances and Exits
Author: Venktesh Pandey
Publisher:
Total Pages: 348
Release: 2020
Genre:
ISBN:

Express lanes or priced managed lanes provide a reliable alternative to travelers by charging dynamic tolls in exchange for traveling on lanes with no congestion. These lanes have various locations of entrances and exits and allow travelers to adapt their route based on the toll and travel time information received at a toll gantry. In this dissertation, we incorporate this adaptive lane choice behavior in improving the dynamic pricing and long-term planning models for managed lanes with multiple entrances and exits. Lane choice of travelers minimizing their disutility is affected by the real-time information about tolls and travel time through variable message signs and perceived information from past experiences. In this dissertation, we compare various adaptive lane choice models differing in their reliance on real-time information or historic information or both. We propose a decision route lane choice model that efficiently compares the disutility over multiple routes on an express lane. Assuming drivers’ disutility is only affected by tolls and travel times, we show that the decision route model generates only up to 0.93% error in expected costs compared to the optimal adaptive lane choice model, making it a suitable choice for modeling lane choice of travelers. Next, using the decision route lane choice framework, we improve the current dynamic pricing models for express lanes that commonly ignore adaptive lane choice, assume simplified traffic dynamics, and/or are based on simplified heuristics. Formulating the dynamic pricing problem as an MDP, we optimize the tolls for various objectives including maximizing revenue and minimizing total system travel time (TSTT). Three solution algorithms are evaluated: (a) an algorithm based on value-function approximation, (b) a multiagent reinforcement learning algorithm with decentralized tolling at each gantry, and (c) a deep reinforcement learning assuming partial observability of traffic state. These algorithms are shown to outperform other heuristics such as feedback control heuristics by generating up to 10% higher revenues and up to 9% lower delays. Our findings also reveal that the revenue-maximizing optimal policies follow a “jam-and-harvest” behavior where the toll-free lanes are pushed towards congestion in the earlier time steps to generate higher revenue later, a characteristic not observed for the policies minimizing TSTT. We use reward shaping methods to overcome the undesired behavior of toll policies and confirm transferability of the algorithms to new input domains. We also offer recommendations on real-time implementations of pricing algorithms based on solving MDPs. Last, we incorporate adaptive lane choice in existing long-term planning models for express lanes which commonly represent these lanes as fixed-toll facilities and ignore en route adaptation of lane choices. Defining the improved model as an equilibrium over adaptive lane choices of self-optimizing travelers and formulating it as a convex program, we show that long-term traffic forecasts can be underestimated by up to 45% if adaptive route choice is ignored. For solving the equilibrium, we develop a gradient-projection algorithm which is shown to be efficient than existing link-state algorithms in the literature. Additionally, we estimate the sensitivity of equilibrium expected costs with demand variation by formulating it as a convex program solved using a variant of the gradient projection algorithm proposed earlier. This analysis simplifies a complex express lane network as a single directed link, allowing integration of adaptive lane choice for planning of express lanes without significantly altering the components of traditional planning models. Overall these models improve the state-of-the-art of pricing and planning for managed lanes useful for evaluating future express lane projects and for operations of express lanes with multiple objectives

Investigating the Value of Time and Value of Reliability for Managed Lanes

Investigating the Value of Time and Value of Reliability for Managed Lanes
Author:
Publisher:
Total Pages: 79
Release: 2015
Genre: Express highways
ISBN:

This report presents a comprehensive study in Value of Time (VOT) and Value of Reliability (VOR) analysis in the context of managed lane (ML) facilities. Combined Revealed Preference (RP) and Stated Preference (SP) data were used to understand travelers' choice behavior regarding the usage of MLs. The data were obtained from the South Florida Expressway Stated Preference Survey conducted by the Resource Systems Group, Inc. (RSG), which gathered information from automobile drivers of South Florida who had recently made a trip on I-75, I-95, or SR 826 corridors. Various modeling and analysis approaches were employed to further reveal user heterogeneity in VOT and VOR.

Understanding and Estimating the Value Travelers Place on Their Trips on Managed Lanes

Understanding and Estimating the Value Travelers Place on Their Trips on Managed Lanes
Author: Sunil N. Patil
Publisher:
Total Pages:
Release: 2011
Genre:
ISBN:

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.