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

Travelers' value of travel time savings (VTTS) are often used to estimate thebenefits of transportation facilities, including managed lanes (MLs). With variouseligibility criteria and time of day pricing on the MLs, the VTTS estimation iscomplicated. This is evident by the underestimation of VTTS on MLs in many of theprevious studies. This study investigates stated preference (SP) survey design strategiesand differentiating the VTTS for ordinary and some common urgent situations faced bythe travelers in an attempt to improve on VTTS estimation on MLs.This study used three different survey design strategies (including a D-efficientdesign) in an internet based survey of Katy Freeway travelers. It was found that arandom attribute level generation strategy, where the VTTS presented in the alternativewas adjusted based on the answer to a previous SP question, performs better than theother two designs with respect to VTTS estimation and other survey design efficiencycriteria.The analysis to differentiate the VTTS for ordinary and urgent trips was carriedout using the state of art in the mixed logit model estimation. It was found that travelersvalue their travel time savings much more when facing most of these urgent situationsrather 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 levelranges were found to significantly affect the VTTS estimation.Further, in order to understand the policy implications of these findings it wasdemonstrated that classifying all trips as ordinary can significantly underestimate theVTTS benefits offered by the MLs. Additionally, the VTTS of any urgent trips would begreatly underestimated. The study also demonstrated that many of the low and mediumincome group travelers on urgent trips can have VTTS greater than that of the highestVTTS traveler from the high income group on an ordinary trip. These findings havesignificant policy implications since the benefits of MLs (and of most transportationinvestments) are primarily derived from travel time savings. Underestimating the VTTSand hence the benefits for MLs can result in reducing the likelihood of funding suchfacilities. This study provides an important first step in the proper estimation of thesebenefits by suggesting modifications to SP surveys to better capture the influence ofurgent trips on the value of a ML facility.