Investigating surrogate safety measures at midblock pedestrian crossings using multivariate models with roadside camera data

This study aims to evaluate and compare Surrogate Safety Measures (SSMs) at five midblock Rectangular Rapid Flashing Beacons (RRFB) and two midblock Pedestrian Hybrid Beacons (PHB) sites in Florida using extensive video data collected over the study period of July to November 2021. Computer vision and data processing resulted in four pedestrian SSMs, namely spatial gap, temporal gap, relative time to collision (RTTC) and Post Encroachment Time (PET). An initial investigation of the SSMs using Mann-Whitney-Wilcoxon tests revealed significant differences in the SSM values across different treatment types and hours of the day. Additionally, univariate regression of spatial gap, and multivariate regression of temporal gap, RTTC and PET revealed significant differences of SSMs across RRFB and PHB sites. The study considered both linear and non-linear (gamma, inverse Gaussian and lognormal) regression models. After considering various traffic and operational parameters, the data were aggregated for each pedestrian-vehicle interaction on each lane to create a total of 395 observations. The SSMs included average spatial gap, temporal gap, RTTC and PET for each interaction of pedestrian and vehicle on each lane. The results indicated that non-linear models performed better than the linear models. Moreover, the presence of the PHB, weekday, signal activation, lane count, pedestrian speed, vehicle speed, land use mix, morning period and pedestrian starting position from the sidewalk have been found to be significant determinants of the SSMs. Results also suggest temporal SSMs increase at the PHB sites compared to the RRFB sites, indicating an improvement of traffic safety at PHB sites. However, the spatial gap decreased for PHB sites compared to the RRFB sites, which suggests that pedestrians tend to start to cross the RRFB sites when they perceive vehicles to be further away than at the PHB sites.

Automated summary

This study evaluates and compares Surrogate Safety Measures (SSMs) at different midblock sites equipped with Rectangular Rapid Flashing Beacons (RRFB) and Pedestrian Hybrid Beacons (PHB) in Florida. Extensive video data collected from July to November 2021 is used to analyze four pedestrian SSMs, including spatial gap, temporal gap, relative time to collision (RTTC), and Post Encroachment Time (PET). The study finds significant differences in SSM values across different treatment types and hours of the day through statistical tests. Regression analysis reveals significant differences in SSMs between RRFB and PHB sites. Non-linear models outperform linear models in predicting SSMs. Factors such as the presence of PHB, signal activation, and pedestrian and vehicular characteristics are found to be significant determinants of SSMs. Results suggest improved traffic safety at PHB sites compared to RRFB sites in terms of temporal SSMs, but decreased spatial gaps at PHB sites indicate pedestrians perceive vehicles to be closer than at RRFB sites.