Exploring network scale separation strategies for car-bicycle integration

• Exploring an approach that separates bikes and cars into different roads in network. • Simulated road and intersection results assembled into network. • Efficiency trade-off in general between bikes and cars when separating. • Bike and car separation on mid-class and local roads improves cycling environment. • Wide car-only lanes on high-class roads speed up cars and ease cycling. This study investigates strategies to mitigate car–bicycle conflicts in mixed traffic and their impacts on traffic speed and safety. It proposes and evaluates an approach that separates bicycles and cars onto different roads in a network. Various scenarios were compared with a baseline, accounting for traffic volume, modal share, and road hierarchy where bicycles and cars are separated. The performance of each scenario was evaluated from the perspectives of motorists and cyclists, considering car and bicycle efficiency across different trip lengths, as well as cycling stress levels assessed using the Level of Traffic Stress (LTS) score. The methodology involved estimating travel times using a traffic simulator and generating reachable areas for bicycles and cars. The study provides insights for designing multimodal transportation systems that consider both the benefits of shared road space and the potential advantages of separating bicycles and cars onto different roads. The main results are as follows: (1) Cars and bicycles show a trade-off relationship in transport efficiency in all network scenarios; the scenarios differ in the road hierarchy levels at which car and bicycle traffic are separated onto different roads; (2) Separating bicycles from cars on middle-class and local roads can upgrade the cycling environment, including efficiency and comfort, both on roads and at intersections; (3) To reconcile conflicts between motorized speed and cyclists’ comfort, enlarging high-hierarchy roads for car-dedicated use can be effective.