BICYCLE FACILITY DESIGN REVIEW/INTERSECTION
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An intersection is where two or more roads meet or where a road and sidepath or trail meet. Intersections can include several travel lanes, divided or undivided, with varying traffic speeds and volumes. Intersections may be controlled through signs or traffic lights or may be uncontrolled. Four-way intersections are the most usual type although several other common geometries such as three-way (or T-intersections) exist. Roads may also cross over each other above grade but only intersections with roads at the same level (at-grade crossings) are considered here.
Design Standards & Guidelines—On-road intersection:
Design Standards & Guidelines—Off-road intersection:
- Compact intersections with roads meeting at right angles are safer for bicyclists to navigate
- Free-flowing and high-speed turning by vehicles should be avoided
- Vehicles may turn right into forward-moving bicyclists (known as the "right hook")
- Right-turning trucks or buses in particular have significant blind spots when turning
- Right-turn only lanes can cause conflicts with through riders
- Tighter curb radii are effective in slowing down turning vehicles
- Lighting is important for safe riding, particularly at intersections
- Bike lanes may be dashed prior to intersections and are usually not striped through intersections although some marking guidance may be provided
- Drivers may not see bicyclists entering crosswalks, causing a high crash rate
- Drivers do not anticipate bicyclists appearing from unexpected path directions
- Visibility of crossing should be increased for both road and path users
- Clear sight distance needs to be maintained for all paths, driveways and turns
- Intersection crossings should be as close as possible to 90 degrees
Traffic Lights:
- Signal should be timed so that bicyclists do not have excessively long waits
- Traffic signal system should be able to detect bicycles (see AASHTO Bike Guide)
- Suggest pavement marking or sign indicating where bicyclist must stop in order to activate the signal
- Extra time is needed for bicyclists to clear green light phases, more if starting from a stop
- Sidepath users need crossing signals at some road intersections
- Consider converting complex intersections to roundabouts
- Video detection signals, which can more successfully detect bicycles over a wider area, are being used more widely in Virginia
Review Checklist:
- Layout and design for bicycling
- Through-riders and positioning
- Off-road crossings
- Left- and right-turning movements
- Right-turn only lane
- Sight distance and visibility
- Location and design of crosswalks and driveways
- Signal detector system
- Curb depressions and radii
- Bus stops around intersection
- Bike lanes and markings
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Guide for Reviewing Public Road Design and Bicycling Accommodations for Virginia Bicycling Advocates