Abstract Manager

The City of Montreal officially adopted its Vision Zero policy in 2015, with the aim to eliminate serious traffic-related injuries and deaths by the year 2040. For decision makers and staff in the City’s central administration and its 19 boroughs, there is still no shared understanding of what Vision Zero entails in terms of street design and engineering principles. This presentation provides an overview of a design guide that has been developed to fill this gap.

The guide is based on two fundamental tenets:

1. Users are fallible: they don’t always follow the rules and behave as designers expect;
2. Users are vulnerable: they can only absorb a limited amount of energy before being seriously injured or killed.

The challenge for designers is framed as creating a system that is realistic about human behaviour and in which unexpected behaviours are “forgiven”.  This means that collisions might still occur, but they do not result in a user being seriously injured or killed.

On one hand, the guide addresses strategies for closing the gap between expected and actual user behaviours, in a broad sense and not just in terms of compliance with traffic regulations. Both voluntary and involuntary deviations from expected behaviours are considered. The former are presented as possible manifestations of a mismatch between the street's design and users’ needs. The latter are presented as likely manifestations of an environment that imposes a high cognitive load on users, causing them to make mistakes. The roles of geometric design and traffic signals in better meeting users’ needs and helping them avoid errors by simplifying complex tasks are discussed.

On the other hand, the guide addresses strategies to maximize the “forgiveness” of the many unexpected behaviours that will inevitably still occur. Three key concepts are explored:

1. Visibility: the ability to see and be seen and to respond to other users;
2. Speed: the amount time available for users to react and the amount of energy exchanged in case of a collision;
3. Separation: physical measures that can prevent users from colliding.

In each case, the design and safety ramifications and the practical limitations of applying the concept in an urban environment are discussed.

The presentation will conclude with several real-world examples, from Montreal and elsewhere, that embody the various concepts and design considerations discussed throughout the guide.