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原文传递 Travelers’ Value of Time and Reliability as Measured on Katy Freeway.

题名：	Travelers’ Value of Time and Reliability as Measured on Katy Freeway.
作者：	Burris, M.; Spiegelman, C.; Abir, A. K. M.; Lee, S.
关键词：	Travel time savings##Travelers##Katy Freeway##Texas (state)##Congestion##Travel time##
摘要：	The value of travel time savings (VOT) is an estimate of what travelers would be willing to pay in order to save time on a particular trip. If travelers would pay $1 to reduce their travel time by six minutes, then they have a VOT of $10 per hour. VOT allows the measurement of benefits derived from transportation projects that reduce congestion and travel time, and is used to justify infrastructure investments or help determine toll road viability. The Texas Department of Transportation (TxDOT) requires accurate estimates of traveler VOT in various project selection and contracting processes. Travelers also place value on trips that are reliable and would be willing to pay for trips that have a predictable travel time regardless of when that trip occurs. The value of reliability (VOR) is therefore equivalent to the amount of money travelers would be willing to pay to reduce the variation in their expected travel time. VOR is less commonly used than VOT but is becoming an increasingly prominent metric in assessing the value of mobility improvement projects. TxDOT does not currently use VOR in its various contract selection or contracting processes. VOT and VOR are commonly estimated using stated-preference (SP) methods where travelers are presented with a series of different travel scenarios with an associated cost and asked to indicate their preference. VOT estimates used by TxDOT are based on SP methods using data from a 1986 TxDOT research project. These VOT estimates have been adjusted each year by the change in the consumer price index. In 2014, the TxDOT-recommended VOT was $21.73 per hour for passenger travel. This value is similar to VOTs used by other departments of transportation and Federal Highway Administration guidance. However, because this value is based originally on 1986 data, there may be a need to update it with more recent data sources. Technology is increasingly enabling the generation of VOT and VOR estimates based on revealed preference (RP)–based methods. These methods differ from SP methods in that they are based on actual travel behavior. This report presents an effort by researchers at the Texas A&M Transportation Institute to generate new VOT and VOR estimates based on RP methods using data collected over a three-year period from transponders on Katy Freeway in Houston, Texas. Initial VOT was estimated to range from $1.96 per hour to $8.06 per hour for all travelers with a transponder, which is considerably lower than most research results and what is generally used in practice. This could be due to the fact that approximately 11 percent of travelers chose to pay to use the tolled managed lanes even when these lanes were running slower than the adjacent general-purpose lanes. The research team also found that only a small percentage (7 percent) of vehicles that had a transponder and were therefore able to use the tolled managed lanes actually did so. When only paid trips on the managed lanes are examined, those travelers are paying the equivalent of $39.65 per hour on average. Therefore, those who do use the lanes appear willing to pay a high amount per time saved. Since this is a small percentage of travelers, the overall VOT for all transponder-equipped vehicles was quite low. Initial VOR estimates were inconsistent with what might be expected. The research team therefore examined a smaller sample of trips that did not include uneconomical trips (i.e., those where travel time was slower or the travel time was less reliable in the tolled managed lane). These new estimates revealed VOT ranges from approximately $0 per hour to over $26 per hour and VOR ranges from $8 per hour to $3 per hour, with many estimates being close to $0 per hour. These VOT results are much lower than what is used in practice, which is derived from SP surveys in which travelers are asked what route they would take given specific travel times and tolls. These VOTs have been used to predict toll road demand with reasonable accuracy. Thus, the values found in this research would appear to be too low, but the values are what travelers are actually paying. Similarly, there appears to be little value placed on added reliability. The research team attempted to determine why this difference exists, but they do not have a definitive answer. It may stem from the fact that a fairly small proportion of Katy Freeway travelers are willing to pay for the managed lanes. Only 7 percent of trips of vehicles with transponders chose to pay to use the managed lanes. A transponder is required to pay the toll, meaning a large portion of eligible vehicles are using the general-purpose lanes in addition to all of the vehicles without transponders that are also making general-purpose lane trips. This small percentage of total trips in the managed lanes brings down the average VOT. This is occurring even though the travelers who are paying for the managed lanes pay an average of nearly $40 per hour for travel time savings. Further research is needed to determine if this difference in VOT is unique to the Katy Freeway managed lanes or managed lane facilities in general.
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报告类型：	科技报告