Abstract: In this paper, we describe the design and development of a virtual environment for evaluating the effectiveness of a mobile application that helps prevent pedestrian accidents when crossing streets. Pedestrian safety is a serious concern in urban environments, and most accidents happen when pedestrians are crossing streets. Recent studies have shown that increased mobile phone use among pedestrians leads to increased distraction and unsafe behavior. To address this issue, we have developed a mobile phone application that alerts pedestrians before they cross potentially dangerous streets. To evaluate the effectiveness of this application, we developed a virtual environment (VE) to simulate the urban environment around our university campus. We recruited a group of students to test the mobile application in the VE by having them virtually walking on the street while talking on the phone. The motion of the virtual pedestrians in the VE were recorded by the program and analyzed to study the pedestrian behavior with and without the safety alert application. We want to know whether the safety alert mobile application could increase the pedestrians awareness and reduce the risky behavior when the pedestrian is crossing a potentially dangerous street. The results show that this VE provides an efficient, flexible, and well controlled environment for public health and geosciences researchers to test their hypotheses and explore alternative solutions. Although the VE cannot replace the real world field testing, the flexibility to manipulate and control the virtual environment and the ability to monitor the pedestrian behavior in real-time prove to be a powerful feature.