Document Type


Date of Award



College of Science, Engineering, and Technology (COSET)

Degree Name

MS in Transportation Planning & Management

First Advisor

Professor Lei Yu, Advisor

Second Advisor

Associate Professor Fengxiang Qiao


Collisions in the work zone have always been a contributing factor to compromising safety on urban roadways. The National Highway Traffic Safety Administration (NHTSA) and the State Transportation Authorities have implemented many safety countermeasures to reduce forward collisions in work zones. However, due to the complexity of traffic in a work zone, traditional countermeasures often fail to prevent crashes. As such, smart warning systems can be applied to notify motorists about the upcoming conditions in work zones. In this study, smartphone-based warning systems were designed to investigate (Phase-A) effectiveness in notifying users about the presence of a work zone and reducing forward collisions through advanced warning area and (Phase-B) the potential to reduce worker fatalities in activity areas. The smartphone-based warning system app was designed by using MIT App Inventor 2. In Phase-A, four different warning messages were generated (visual, sound, male voice and female voice) to alert drivers. Driving simulator tests with twenty-four participants with one hundred and twenty rounds through work zones were conducted to investigate the impacts of smartphone-based warnings on performance measures such as headway distance, headway time, speed, and acceleration/deceleration. 1 2 In Phase B, three different warning message systems (sound, male voice and female voice) were designed to alert drivers. Driving simulator tests were conducted with twenty-four participants in ninety-six rounds of driving in a work zone to investigate the impacts of smartphone-based warning messages on performance measures speed, speed variation, acceleration, and brake reaction distance. In Phase-A, the statistically analyzed results show that, with the help of voice (either female or male) warnings regarding forward collisions, acceleration and speed were reduced, and the headway time and braking distance increased. The headway distance was increased a certain distance; after that, it gradually decreased. Moreover, participants found the notification system to be user friendly and felt that it helped to avoid rear-end crashes in work zones. In Phase-B, the statistically analyzed results showed that, with the assistance of sound and voice (either female or male) warning messages, drivers could effectively reduce their speeds. Meanwhile, such warning systems can also reduce the brake reaction distance and increase the headway time and headway distance. Overall, no statistically significant difference between the male and female voice were found. Thus, voice warning from either a male or female voice is the best option to reduce forward collision and worker fatalities. These driving simulator-based studies found that the smartphone-based warning system is effective in reducing both vehicle-to-vehicle crashes and worker fatalities. It is recommended that such a low-cost and effective smartphone application should be tested in real road conditions with similar safety measures to those employed in this paper. Keywords: Work Zone, Advance Warning Area, Activity Area, Forward Collision, Fatality, Driving Simulator, Smartphone.