| dc.description.abstract | Significant advancements in pedestrian safety have been achieved in automotive design over the past century, as evidenced by the adoption of rounded vehicle shapes, increased bumper coverage, and the implementation of policies such as speed limits and vehicle safety assessment programmes. In contrast, subway-to-pedestrian collisions remain a growing concern, receiving comparatively less attention regarding passive safety measures. While collision avoidance interventions such as Platform Screen Doors have proven effective, they are not always feasible in older subway networks, such as the NYC subway system.
At the onset of this research, the most recent epidemiological data for NYC subway-to-pedestrian collisions covered incidents from 1990 to 2007. This study seeks to update and expand upon that previous work by analysing 185 subway-to-pedestrian incident reports from 2019, as provided by the Public Transportation Safety Board (PTSB), to offer biomechanically relevant insights that were previously unavailable in academic literature. The updated data refines the distribution of incidents by sex, age, and geographic area, demonstrating nearly equivalent distributions of standing, jumping, and lying pedestrian postures at the moment of impact. It identifies 12m/s as the most common impact velocity, with 97% of incidents occurring within 60m of a station platform. Elevated stations showed a higher fatality rate (40%) compared to below-ground stations (27%), with drainage troughs highlighted as a potential mitigating factor.
The literature review identified a lack of PMHS (post-mortem human subject) or ATD (anthropomorphic test device) data specific to subway-to-pedestrian collisions. At present, the characteristics of pedestrians predominantly dictate the effective contact stiffness in such impacts; however, the introduction of energy-absorbing countermeasures alters this dynamic. To mitigate this gap, nine controlled impact tests were performed utilising a cylindrical headform and DC-coupled accelerometer. The derived force-penetration relationships for foam, as well as foam encased in 1mm aluminium or 3mm ABS shells at impact velocities of 7.5, 10, and 11.5m/s were validated using multibody modelling software (MADYMO). This validation demonstrates its effectiveness for future countermeasure modelling.
The first baseline subway-to-pedestrian model was developed to evaluate the current risks associated with head and run-over injuries. Using 1920 simulated scenarios informed by the PTSB data, the model revealed a significant risk of wheel contact during run-over events, irrespective of train entry velocity. The incorporation of a 0.5m drainage trough resulted in a 50% reduction in run-over risk, thereby validating its safety advantages. These findings indicate that policies which concentrate exclusively on reducing train entry speed would have minimal impact on the reduction of run-over injuries.
Three countermeasure designs were evaluated using a reduced simulation test matrix: three impact velocities (8, 10, and 12m/s) and a trough depth of 0.75m. Modular panels attached to the train front significantly reduced head injury risk (90%) and pedestrian-to-train wheel contact risk (58%), with greater effectiveness observed when a larger frontal area was covered. A rail guard design successfully decreased secondary contact injuries; however, it inadvertently heightened the risks of run-over and amputation due to altered pedestrian kinematics.
This research represents an advancement in the field of subway-to-pedestrian collision safety, providing key insights into biomechanics and engineering design across four pillars of biomechanical safety research. By addressing previously unexplored aspects of impact dynamics, pedestrian injury mechanisms, and countermeasure efficacy, this thesis establishes a foundational framework for enhancing subway safety worldwide. The findings highlight that targeted design interventions, such as energy-absorbing countermeasures and optimised drainage troughs, can significantly reduce the risks of fatal head injuries and train wheel contact during subway-to-pedestrian collisions. This work not only bridges the gaps in biomechanical understanding but also lays the groundwork for future policy, design, and simulation-based advancements aimed at mitigating subway-related fatalities and injuries in both legacy and modern transit networks. | en |
