CYCLIST PEDESTRIAN INTERACTIONS IN SHARED SPACE USING 1 AUTOMATED VIDEO CONFLICT ANALYSIS 2 3 4 5
Year: 2016

1 In the past decade, transportation planners worldwide have been incorporating shared space design 2 elements as a way of creating pedestrian friendly places. Streets incorporating shared space principles 3 tend to have reduced vehicle speeds and increased safety for vulnerable road users. In North American 4 cities, a shared space approach is rarely applied to non motorized environments such as pedestrian malls, 5 campuses, and parks. As cyclist and pedestrian speed distributions overlap, there is an opportunity to 6 provide safe and convenient infrastructure to both through non motorized shared spaces. Yet, little 7 empirical evidence exists concerning the risk of pedestrians and cyclists interactions in shared spaces. To 8 evaluate the safety of these spaces, a methodology is developed for semi automated pedestrian cyclist 9 conflict analysis at high volume intersections in non motorized shared space. Measures of pedestrian and 10 cyclist speed, angle of approach, pedestrian density and time to collision are analyzed to estimate the risk 11 of pedestrian cyclist interactions for different conditions. The methodology is then applied to a case study 12 on the McGill University campus in Montreal, Canada, where pedestrians and cyclists co exist with 13 limited presence of motorized vehicles. Pedestrian and cyclist user trajectories were automatically 14 extracted using a computer vision software to yield 2739 pedestrian cyclist interactions for analysis. 15 Speed and pedestrian density are shown to be negatively correlated, while conflict rate and density are 16 positively correlated. Although a high pedestrian density increases the likelihood of conflict, it also 17 reduces cyclist speed. Statistical differences were shown between conflict types defined based on 18 intersecting angle and road user configuration. 19 Beitel, Stipancic, Manaugh, Miranda Moreno 3  Two core objectives of traditional urban street design are efficient vehicle flow and adequate safety for all 2 road users (1; 2) Physically separating road user types into dedicated areas was a relatively simple way to 3 meet those objectives. In extreme examples, guardrails, pedestrian bridges, and tunnels were constructed 4 to eliminate or reduce conflicts between road users while allowing for high vehicle speeds and flow. 5 However, with new objectives including walkability and the quality and comfort of the pedestrian realm 6 becoming integrated into policy, transport planners are increasingly conceiving streets as part of larger 7 public and social life of residents, not solely as space for unimpeded automobile flow. In turn, there has 8 been a trend away from traffic segregation, toward street design aimed at reducing vehicle speeds and 9 increasing safety for vulnerable road users. In this framework, design principles based on creating 10 pedestrian friendly spaces, (for example, complete streets, traffic calming, or shared space) have gained 11 prominence (3) In many North American cities, efforts to calm traffic on key commercial streets have 12 been made, and several cities have implemented shared space design principles to achieve those goals (4; 13 5) 14 The pedestrian mall was designed as a pedestrian only street (maximum user segregation) 15 intended to improve pedestrian safety and enhance the pedestrian experience. Beginning in the 1960s and 16 1970s, hundreds of pedestrian malls were created in North America. Many were underutilized and did not 17 achieve original objectives, and were converted back to conventional streets by the 1990s (6) One factor 18 that plagued pedestrian malls was that pedestrian traffic alone was insufficient to support high levels of 19 activity (6) Studies of six pedestrian malls found that shared malls (which allow for a limited amount of 20 vehicular traffic) and transit malls (which incorporate transit lines) had significantly greater activity 21 throughout the day resulting in lower commercial vacancy rates (6) Very few pedestrian malls in North 22 America could be considered non motorized shared spaces. The majority of pedestrian malls have a 23 dismount policy for cyclists and forbid the use of rollerblades and skateboards. Despite the limited 24 number of on street examples of non motorized shared spaces, several examples can be found where 25 cyclists and pedestrians co exist, including shared off street paths, university and health service 26 campuses, public parks, and sidewalks. In some cases, these environments are formally shared spaces for 27 pedestrians and cyclists, while in others, unauthorized cyclists occupy the same space as pedestrians as 28 the status quo. 29 Over the past decade, cycling demand in urban centers has increased dramatically and has not 30 been met with a sufficient provision of infrastructure in many jurisdictions. As cyclists and pedestrians 31 travel at relatively similar speeds compared to motorized vehicles, opportunities exist to provide safe and 32 convenient infrastructure to vulnerable road users through non motorized shared spaces in urban 33 environments. Although pedestrians and cyclists currently co exist along trails, parks, and campuses, few 34 studies have sufficiently explored the level of safety provided by these facilities (7) It is worthwhile to 35 investigate how pedestrians, cyclists, or other active users interact in non motorized shared spaces with 36 the objective of estimating safety, considering potential associated factors including user demand, speed, 37 and approach, and weather conditions or other site specific characteristics. 38 Studying the safety of vulnerable road users using traditional crash based methods is almost 39 impossible, as collisions between them are relatively rare and difficult to observe, requiring years of data 40 collection for a robust analysis (8; 9) The purpose of this paper is to explore interactions between 41 pedestrians and cyclists in shared space using semi automated video conflict analysis. The study 42 objectives are to; develop a method for automated video analysis of pedestrian cyclist interactions at 43 intersections in non motorized shared space; to propose novel means of evaluating safe behavior in such 44 environments, and; to present a case study on the McGill University Campus in Montreal, Canada where 45 high volumes of pedestrians and cyclist interact. The following sections present the literature related to 46 safety of shared spaces and traffic conflict techniques, the proposed methodology for automated conflict 47 analysis, a description of the data, and results of the safety analysis at McGill University. 48