Kasem Choocharukul

Effects of Attitudes and Socioeconomic and Travel Characteristics on Stated Route Diversion: Structural Equation Modeling Approach of Road Users in Bangkok, Thailand

At present, the application of the variable message sign (VMS) is considered an undeniably practical tool for providing travel information to motorists. Several studies have attempted to examine the effects of socioeconomic and travel characteristics on diversion behavior; however, the direct investigation of the extent of motorists’ attitudes, in conjunction with the aforementioned variables, has not been given much attention. Therefore, the primary objective of the present study is to gain a better understanding of the interrelationships between the likelihood of route diversion, attitudinal variables, and several exogenous factors such as motorists’ socioeconomic status and travel habits. In this study, a structural equation model is developed based on empirical data on road users in Bangkok, Thailand. Derived from factor analysis, three attitudinal variables, namely, awareness of the VMS, VMS comprehension, and perceived VMS usefulness, are extracted and incorporated into the structural equation modeling framework. Modeling results suggest a direct relationship between stated route diversion and two of the attitudinal variables, that is, VMS comprehension and perceived usefulness of the VMS; the awareness of VMS is not found to be a direct determinant of the decision to divert a route. Exogenous variables that appear to be of statistical significance include education, gender, age, daily mileage, and trip purpose. Unlike those in past studies, none of the socioeconomic variables in this study appears to directly influence plans to divert a route. The model estimation results are discussed and practical implications are provided.

Psychological Determinants of Moral Obligation of Car Use Reduction and Acceptance of Car Use Restriction in Japan and Thailand

In this study determinants of moral obligation of car use reduction and acceptance of car use restriction were investigated. This was based on attitudinal image variables for cars and public transport, including symbolic/affective, instrumental, and social orderliness attitudinal-aspects. Attitudinal data were collected by means of a questionnaire survey in Japan and Thailand, specifically in the cities of Tokyo (n = 402), Bangkok (n = 100), and Ubon Ratchathani (n = 76). Results from structural equation modeling indicated that image variables had no effect on the acceptance of car use restriction in Thailand; however, some image variables had certain impacts in Japan. The findings imply that communicative strategies to change the image of car and public transport would be effective in increasing public acceptance of coercive transportation measures in Japan, but such strategies might not be promising in Thailand. In addition, it was found that fewer attitudinal-aspects of car use had significant effects on a moral obligation to reduce car use and acceptance of car use restriction in Thailand than in Japan. This finding also implies that it might not be easy to reduce car use in Thailand by utilizing communicative measures such as mobility management that have proven to be effective in Japan.

Psychological Factors Influencing Behavioral Intention Toward Future Sky Train Usage in Phnom Penh, Cambodia

A study is presented on an extension of the theory of planned behavior (TPB) to investigate the commuters behavioral intention toward future sky train usage in Phnom Penh, the capital city of Cambodia. Several psychological factors and socioeconomic variables that might help explain the likelihood of future sky train usage were measured by a questionnaire survey. Responses were collected from 398 motorcyclists who traveled along the planned sky train line linking the central market in the central business district to the airport. The survey was conducted on the basis of psychological constructs, including attitude, subjective norm, perceived behavioral control, moral obligation, and awareness of consequence. With structural equation modeling, it was found that the main TPB constructs, that is, attitude, subjective norm, and perceived behavioral control, significantly influenced the behavioral intention of using the future sky train. A further investigation revealed that moral obligation and the awareness of consequences were also found to be significant determinants for the behavioral intention. In addition, to some degree, socioeconomic variables can also be used to explain the intention. The outcome of the study can help in understanding commuters’ current behavioral intention and give some ideas on the feasibility of such an investment in regard to potential demand.

Short-Run Route Diversion: An Empirical Investigation into Variable Message Sign Design and Policy Experiments

Variable message signs (VMSs) can convey several traffic and roadway information to motorists. Using empirical stated preference (SP) data from road users in Bangkok, Thailand, we demonstrate that short-run route diversion can be estimated and forecast based on different VMS message-content attributes via mixed logit and logit models in which the motorists stated route diversion is the dependent variable. The findings reveal that different message contents lead to different levels of route-changing propensity. Route diversion in Bangkok is likely when a VMS displays a suggested route and qualitative information. The framing effect on route-choice decision explains the finding of qualitative delay information preference to its quantitative counterpart. To determine the policy implications, we further investigate the developed models by estimating changes in the probability of the stated route choice due to changes in the message content. Three VMS message policy experiments are conducted using the model: enforcing quantitative delay content, enforcing qualitative delay content, and enforcing suggested route content. The results show that qualitative delay information and the suggested route reduce the ambiguity of the message quality. The optimal VMS designs for short-run traffic management to encourage/discourage route diversion are discussed.

Simple Method of Predicting Travel Speed on Urban Arterial Streets for Planning Applications

Travel speed is a key measure of effectiveness in evaluating urban arterials. The Highway Capacity Manual (HCM) methodology of predicting speeds along urban streets requires complex calculations and input not typically available in long-range planning. The use of default values is therefore necessary. This paper demonstrates that a simple and practical method of estimating travel speed along urban arterial streets is possible. An equation derived from the HCM delay formula and calibrated with the results obtained from CORSIM, a microsimulation model, is proposed. The equation requires neither signal characteristics nor detailed traffic and geometry information about arterial intersections. The proposed model of travel speed along urban arterials uses only input available to planners. The model is evaluated with the results obtained from a field study in Lafayette, Indiana. Despite its limited scope of input and simple structure, the model properly replicates the trends found in the field. The model overes...

Development of a Congestion Management System Methodology for the Indiana State Highway Network

A methodology for developing congestion management–related projects for the Indiana state highway network is described. The methodology is based on a sketch planning analysis technique that can be used with limited input data. The software package provides estimates of costs and other effects of potential congestion mitigation projects to undertake in a given year, which can be used by planners and programmers in long-range planning. Project types include road widening, high-occupancy-vehicle facilities, ramp metering, incident management, and arterial traffic signal coordination. The impact is assessed in travel time savings, vehicle operating cost savings, crash cost savings, and emission reductions. An example application of the methodology is given for the 7.81-mi segment of I-65 between Interchanges 116 and 123 in the Indianapolis area.