Empirical Measurement of Travelers' Value of Reliability

Time and reliability are two fundamental factors influencing travel behavior and demand. The concept of the value of time (VOT) has been extensively studied, and estimates of VOT have been obtained from surveys and empirical data. On the other hand, although the importance of value of reliability (VOR) is appreciated, research related to VOR is still in its early stages. The VOR has been estimated using surveys but has almost never been estimated using empirical data. This research used empirical data to take an initial step toward understanding the importance of travel time reliability. Katy Freeway travelers face a daily choice between reliable tolled lanes and less reliable but untolled lanes. An extensive dataset of Katy Freeway travel was used to examine the influence of time, reliability, and toll on lane-choice behavior. Lane choice was estimated using multinomial logit models. Basic models, including only travel time and toll, yielded reasonable results. Models included VOTs of $2.60/hour, $8.63/hour, and $10.71/hour for off-peak, shoulder, and peak-period travelers, respectively. However, adding a managed-lane (ML) alternative specific coefficient to these models resulted in positive coefficients for the toll variable and negative VOTs. Similarly, adding reliability to the models resulted in counter-intuitive results. Researchers concluded that additional research on how travelers perceive the reliability and time savings on MLs is needed because modeling real-world choices of MLs using the standard definitions of reliability and time savings led to counter-intuitive results.