Utilisateur:StephenWoodallKalfaian

Stephen Woodall-Kalfaian

• Program: Master of Applied Science (graduated 2018)
• Contact
• Education: B.Ing Polytechnique Montreal in Civil Engineering
• Research Project
  • Title: Safety Analysis of Roundabout Conversions based on Video Observations
  • Summary:

Roundabouts in North America have been increasing in importance in recent years, as they replace intersections for increased safety and efficiency. The reduction in speeds as well as in the number and severity of collisions while conserving efficient vehicle flow are all advantages that have justified the introduction of roundabouts into recent road designs in North America.

New technologies used in transportation engineering have allowed for better analytical capabilities in the field of traffic safety analysis. The field of computer vision, which has emerged during the seventies, has enabled analysis to be based on video data rather than accident data, the use of which has been standard since road safety analysis studies began post-Second World War.

This research project aims to use the capabilities and increased efficiency of automated video data analysis in order to analyse two roundabout conversion sites following a “before-after” method – the sites are both based in North America (one in New York City, the other in Gatineau, Quebec). Safety analysis related to the roundabout conversions uses surrogate measures of safety, i.e. analysis methods aiming to replace accident data by offering a more proactive way of evaluating safety. The methodology developed for the roundabout conversion evaluation in the context of this research study is based on several, complementary methods of analysis. The objective of the methodology is to analyse the roundabout conversion on a larger scale before adding a more microscopic analysis of road user behaviour. Firstly, a preliminary conflict point analysis helps compare the two different intersection designs in terms of potential hazardous “hotspots” for road users. In a second analysis requiring the use of the software tools (tvaLib and Traffic Intelligence) used to detect and analyse road user trajectories, two well-known safety indicators are used: speed and time-to-collision (TTC) distributions.

A further part of the second analysis method adds to the comparative analysis of the roundabout conversions, and consists of determining the comparable movements between the two intersection configurations, using both the geometrical attributes of the intersections and the preliminary conflict point analysis. The movement analysis method then requires the collection of road user pairs in the set of comparable movements for both intersection configurations. All of these methods aim to compare the performance of the converted roundabout as opposed to the intersection it replaces, in terms of road user behaviour and safety hazard. The results are contrasted; while the roundabout conversion in New York City showed an improvement in terms of slowing road user speeds, there was little change in the median TTC values for user pairs involved in both intersections. Movement analysis showed a decrease in user pairs for the different conflicting movements, yet the results remain inconclusive due to tracking problems. The results for the Jean-Proulx site in Gatineau were also inconclusive, for all analyses, due to camera malfunction and disparities in vehicle counts.

• Publications