Filling the gaps: Building usable transportation networks through level of traffic stress

When people look at a fragmented route, generally called ‘gaps’, they consider their comfort and tolerance as the weakest link in that network. A driver may avoid a route that they feel is travelling too slowly with too many hazards, similarly, a cyclist or walker will deviate from their route to match their level of comfort. Route detours for higher protection can work contextually if the facility is high quality, both in design and feel, and they can still access their destinations. When detours are combined with other benefits, like avoiding climbing hills or a more scenic pathway, there can be real benefits to the cyclist or walker.

There is a level at which the tolerance for detours or adjacent speed volumes cannot be met and the trip becomes effectively impossible for everyone except the most daring. When designing networks and infrastructure, we need to focus on the 'interested but concerned' group; otherwise, options like walking, biking, and transit access will always appear marginal. 

In determining the influence of the level of traffic stress, there are two defining design levers: the speed at which the traffic is travelling and the protection to the cyclist or walker. As the driver is able to travel faster, the level of protection needs to increase; there is a component of volume and vehicle types as well, but for brevity, we isolate speed as the critical criterion. Basically, the faster cars travel, the more protection someone needs. If speeds are slow enough, travelling in mixed streets can be comfortable and direct.  

Not every street is an urban main street. As speeds increase, we look to provide appropriate protection to create that network connection. It is not enough for most users to slap paint on a street against the curb without slowing down traffic to match the level of protection.  

Even if the existing network does not conform to the level of traffic stress, each time a new gap is created, it becomes a barrier to users.

When we work on a project, we aim to allocate space that fosters connections for each traveller. Although small gaps can create significant barriers, understanding these small gaps has allowed us to make a substantial impact on how people travel. By employing the LTS for context-sensitive design, we can link networks that connect trails, side streets, and main routes through our understanding of pedestrian movement. At GHD, we utilize a tool to assist in this process – Strategy to Street. We strive to comprehend destinations and user behaviour within the context of the existing network, which in turn informs the value of each network connection. We recognize that supporting walking, biking, and transit access requires us to understand the communities we've established and how to adjust that network to create a web of connections. By exploring the design principles of speed, volume, and protection, we can introduce new transportation options for the broader community.