Lihui Peng

Pedestrian Safety Analysis in Mixed Traffic Conditions Using Video Data

With the dramatic development of image processing technology, a growing number of traffic flow detection and analyses have been conducted by using video data. Time to collision (TTC) and postencroachment time (PET) are two major parameters used to indicate the severity of a potential collision and to capture an imminent vehicular accident. However, microlevel pedestrian-involved collisions are less studied because they are hard to observe or record. This paper tries to extract the traffic object locations from video data, to define the time difference to collision (TDTC) parameter as a variation from TTC and PET to fit the pedestrian-involved potential collisions/conflicts, analyze the interaction behavior between pedestrian and vehicles, and validate the TDTC parameter in indicating pedestrian safety performance by using 100 groups of interaction data. The results show that the interaction cases with larger TDTC values are safer, whereas the cases with continuously closer to zero TDTC values are more dangerous. About 80% of the cases classified by the TDTC parameter have the same result with the independent observation; if TDTC is combined with vehicle speed, the classification result can be improved. More mixed traffic scenes will be conducted based on this research in the future.

A review of game theory applications in transportation analysis

Game theory has been widely used in various fields since its birth. Particularly, it plays an important role in transportation analysis and provides powerful tools to solve many difficult problems. This paper provides an overview of the numerous applications of game theory in transportation analysis and classifies these applications into two types. We aim to provide a clear framework of these applications and also a feasible solving process of problems. At last, we point out some drawbacks of game theory based applications and discuss how to adjust game theory method to deal with complex situations in future practice.

The delay of bus near a stop when mixed traffic flow is considered

This paper studies the following driving scenario that is common in China and many Asian developing countries: a bus has to temporarily occupy the bicycle lane in order to stop and pick up passengers, where the mixed traffic flow is composed of motorized vehicles and bicycles. A special cellular automation model is proposed to examine the governing factors that influence the delay of a bus near a bus stop. Vehicle inflow rate, bicycle inflow rate and bus inflow rate are specially addressed. Finally, some useful suggestions are presented.

An analysis on traffic flow characteristics and lane changing behaviors in Beijing urban expressway bottlenecks

This paper studies on traffic flow characteristics and lane changing behaviors at two representative locations of Beijing urban expressway bottlenecks. On the basis of real data collection, density-flow characteristic of each lane is analyzed and the factors that affect the frequency of lane changing behaviors are focused on. Results indicate the close relationship between density-flow characteristics and lane changing behaviors.

Vehicle-Pedestrian Interaction Analysis in Mixed Traffic Condition

The interaction between motor and non-motor traffic participators has been increasing dramatically. So far, traffic safety is always measured as the number and severities of traffic collisions which occur. Time to Collision (TTC) is one major parameter to reflect the possibility of such collisions. It can also be applied to the pedestrian involved analysis, but cannot reflect the pedestrian safety precisely. Therefore, time Difference to Collision (TDTC) is defined accordingly as a variation of TTC to describe the pedestrian-vehicle (P&V) interaction. One hundred groups of P&V interaction cases were collected. The comparison was made based on the cases between Vehicle-Pass-First (VPF) and Pedestrian-Pass-First (PPF) and among different safety scenes. The results show that the distance and speed values are obviously different from the cases between VPF and PPF, and the TDTC values are related to safety. It may provide some guidance to describe and analyze the driver-pedestrian interaction behavior. The participators interaction behavior can be discussed further in the future.

Validity of Integrated Signal Control Strategy on Urban Expressways with Three Different Ramp Lengths

This paper studies the validity of integrated signal control strategy on urban expressway and compares its efficiency with other three control strategies. Three traffic simulation models about ramp networks have been built in VISSIM 4.3 in order to test the efficiencies of those signal control strategies under different traffic conditions. Moreover, 6 different traffic flow states were set in each model and the comprehensive evaluation of each strategy is proposed.