Off-Road Cycling Facilities - Sight Triangle Requirements at Stop Controlled Driveway and Side Road Crossings

Increasingly local and regional municipalities are constructing bicycle facilities within the boulevard, whether they be dedicated bicycle lanes or multi-use pathways (MUP’s). In addition, cyclists also often use sidewalks. Cyclists can travel up to 20 km/h and where these cycling facilities cross non-signalized driveways and local roads  there is a significant potential for conflict between cyclists and exiting drivers, especially considering that many drivers are “non-compliant” and do not always stop in advance of the cycling facility.  Therefore such “non-compliant” drivers and cyclists should have enough sight distance to allow them time to observe, initiate and execute the desired actions to avoid a collision. This paper will show that there cannot be a “one size fit all” solution because sight distance requirements are a function of several variables that can differ from location to location. The most critical variable being how far the facility is located from the curb. It is therefore imperative that required sight triangle dimensions be calculated on a site by site basis. The paper will develop and present the mathematical models and tools that can be used to calculate the sight triangle dimensions for any location – for both “compliant” and “non-compliant” drivers.  From an infrastructure design perspective it will increase our understanding on how modifying certain cycling facility design parameters will impact sight triangle dimensions – and hence how we can reduce the risk of conflict between drivers and cyclists. From a land development perspective the models and tools will assist planners and engineers to determine the size of daylight triangle areas that should be kept free and clear of any potential sight line obstructions. when and what type of mitigating measures may be required to reduce conflicts. The TAC Guidelines provides no guidance on sight distance requirements between driveway vehicles and cyclists on cycling facilities. The research aims to fill this gap by using a first principle based approach towards developing guidelines and tools we can use to  minimize conflicts between vehicles an cyclists.