Presently, Thailand has two routes including motorway numbers 7 and 9. The motorway number 7 links between Bangkok and Chonburi with 80 km in length. Additionally, the motorway number 9 serves traffic between Bang Pa in and Bangna with 64 km in length. The total length of this motorway network is 144 km. In 2014, Thailand’s motorway has served 37 million trips, or 242,000 vehicles daily. A single incident blocking one or two travelling lanes would exponentially increase delay on the network.

In this study, the researchers developed the incident prioritization support tool for the motorway’s rescue units using the conjoint analysis and the ordered logit model. The preliminary interview has been conducted to identify the key factors in prioritizing and managing incidents. By interviewing six rescue unit respondents, the researchers have identified the key factors in ranking the incidents including type of vehicles, impact on traffic, number of fatalities, number of injuries. Based on following multiple interview, the researchers utilized the orthogonal design technique to construct the questionnaire.