Quality of traffic flow on urban arterial streets and its relationship with safety

Abstract

The two-fluid model for vehicular traffic flow explains the traffic on arterials as a mix of stopped and running vehicles. It describes the relationship between the vehicles' running speed and the fraction of running vehicles. The two parameters of the model essentially represent 'free flow' travel time and level of interaction among vehicles, and may be used to evaluate urban roadway networks and urban corridors with partially limited access. These parameters are influenced by not only the roadway characteristics but also by behavioral aspects of driver population, e.g., aggressiveness. Two-fluid models are estimated for eight arterial corridors in Orlando, FL for this study. The parameters of the two-fluid model were used to evaluate corridor level operations and the correlations of these parameters' with rates of crashes having different types/severity. Significant correlations were found between two-fluid parameters and rear-end and angle crash rates. Rate of severe crashes was also found to be significantly correlated with the model parameter signifying inter-vehicle interactions. While there is need for further analysis, the findings suggest that the two-fluid model parameters may have potential as surrogate measures for traffic safety on urban arterial streets.

Safety modeling of urban arterials in Shanghai, China

“…They found higher ADTs were associated with increased crashes, and the absence of onstreet parking was associated with reduced injury severity in crashes. Dixit et al (2011) investigated the relationship between arterial operations and crashes in the Orlando Metro using a two-fluid model. This model assumes traffic flow consists of running and stopped vehicles, and uses maximum speed and fraction of running vehicles (ratio of running time per mile to travel time per mile) to describe running speed.…”

Relating Naturalistic Global Positioning System (Gps) Driving Data With Long-Term Safety Performance of Roadways

“…This correlation was also observed from the parameter T m as well, which was observed to have a negative correlation with long-term traffic crash rate (Dixit et al, 2011). Therefore, Grand Avenue with a lower value of T m may have a higher crash rate compared to California Boule-vard.…”

“…Therefore, Grand Avenue with a lower value of T m may have a higher crash rate compared to California Boule-vard. Verification of these long-term traffic safety trends as proposed by Dixit et al (2011) could not be proved with this research due to incomplete traffic accident history available from UC Berkeley's Transportation Injury Mapping System (TIMS) database.…”

“…As discussed in Chapter 2, the Two-Fluid parameters of n and T m have been shown to correlate with total crash rate (Dixit et al, 2011). By obtaining the TwoFluid parameters, a few deductions about the long-term traffic safety of these two arterial roadways can be made.…”

“…For analysis performed for arterial roadways, the Two-Fluid model was determined to be an appropriate model to assess long-term traffic safety performance based on previous literature (Dixit et al, 2011 (2011) these Two-Fluid parameters would suggest that Grand Avenue is more susceptible to a higher crash rates.…”