Protected Intersections
Purpose
Slow vehicle turning and reduce conflicts between pedestrians, bicyclists, and vehicles.
Description
Protected intersections are a type of intersection design that improves safety by reducing the speed of turning traffic, improving sightlines, and designating separate space for all road users. Protected intersections reduce conflict points between drivers and bicyclists by separating the two modes. The separation is achieved through corner islands that reduce vehicle turning speeds and provide an area for vehicles to wait while yielding to bicyclists and pedestrians in the crosswalk. Protected intersections eliminate the merging and weaving movements from vehicles typically found in conventional bike lanes and shared streets. By clearly defining pedestrian and bicyclist spaces and mitigating conflicts between vehicles and vulnerable users, protected intersections provide a safer environment for all modes.
Safety Benefits
- Reduces the speed of vehicles turning right while maintaining appropriate turn radius for larger vehicles.
- Reduces conflict points between pedestrians, bicyclists, and drivers.
- Promotes predictable movement.
- Allows eye contact among drivers, bicyclists, and pedestrians.
- Defines pedestrian and bicyclist operating spaces
View locations where this tool is installed in Arlington County
Street Types and Context
Applicable Street Types
Principal Arterial, Minor Arterial, and Local Principal streets in developed areas.
Other Location Guidance
Protected intersections work best at signalized intersections with high volumes of bicycles and vehicles.
Primary User Groups
Key Implementation Considerations
- Protected intersections often require modifications to corner radii.
- An analysis of traffic conditions and civil engineering impacts must be performed to determine feasibility of design options and consider safety needs against operational tradeoffs.
- Protected intersections must consider accessible paths for people with disabilities.
Expected Crash Reduction
Studies show a reduction in crashes and speed of turning vehicles. However, studies find that separation distance, or the distance between the bicycle crossing and the vehicle through lane from which the turning vehicle is turning, of 6.5 – 16.5 feet, offers the greatest safety benefit with a better safety record than conventional bike lane designs (Schepers et al., 2011).
Cost
Varies based on the amount and type of treatments installed, but a fully built-out intersection has a high cost.
Timeline
Often three or more years for a fully built out protected intersection, although a protected intersection may be delivered in a shorter timeframe using quick-build materials.
References
