Protected Intersections For Bicyclists
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[Protected Intersections For Bicyclists]
[Protected Intersection:] Source: LYBIO.net
Urban planners and designers have finally figured it out: If your city is designed so that you can bike instead of drive, it will be a happier, healthier place to live.
We know that protected bike lanes are the key to getting the average person to consider traveling by bike. Sharing busy traffic lanes with cars is absolutely unacceptable, and separation by a line of paint is often not enough.
‘Protected Bike Lanes’, also called ‘cycle tracks’, use curbs, planters, or parking to buffer bicyclists from moving cars. But there is still a problem. The protected bike lanes lose their benefits when they reach intersections. The buffer falls away, and you’re faced with an ambiguous collection of green paint, dashed lines and bicycle markings. One popular configuration is called “a mixing zone” where cars and bikes share the lane. It doesn’t matter how safe and protected your bike lane is if intersections are risky, stressful experiences.
We need to make intersections just as safe and secure as the lanes that lead into them. What the ‘Protected Bike Lane’ needs, is the ‘Protected Intersection’.
Modeled after Dutch intersection design, the Protected Intersection brings the physical protection along with you as your ride through the crossing. A collection of design elements makes left turns simple and secure, right turns protected and fast, and provides straight through movements that minimize or eliminate conflict from turning cars. With this design, riders will never feel stranded, exposed, or unsure of where to go and how to get there.
There are four main elements to protected intersection designs. A Corner Refuge Island, a Forward Stop Bar for Bicyclists, a Setback bike and pedestrian crossing, and Bicycle Friendly Signal phasing.
The corner refuge island is the key element that makes these intersections function. This island brings the protective barrier from the bike lane far into the intersection. Think of it like a curb extension for bicyclists. The island physically separates bicyclists as they make right turns, and provides a secure refuge for those waiting at a red signal protected from moving cars.
Paired with the corner refuge island is a forward stop bar for bicyclists. While people driving must stop back behind the crosswalk, people on bikes may yield to pedestrians, and stop at a waiting area farther ahead in the intersection. Bicyclists turning left also use this space to wait when making a left turn.
The advantage of this design is three fold:
The forward stop location makes bicyclists incredibly visible to drivers waiting at a red light; the physical distance ahead of cars gives bicyclist an effective head start when the light turns green; and the distance of the road that bicyclists need to cross is greatly reduced.
In Protected Intersections, the bike lane bends away from the intersection creating in a setback bicycle and pedestrian crossing. In contrast to conventional bicycle crossings run next to moving cars, the setback crossings provide the space and time for everyone to react to potential conflicts.
The critical dimension is one car-length of space between the traffic lane and the bicycle crossing, around 6 meters. This space is often already present in the parking and buffer space of the protected bike lane. With this design, drivers turn 90 degrees to face the bike lane before they even cross it, making people on bikes highly visible and out of the driver’s blind spot. To allow for adequate reaction time for all users, use a small effective corner radius to encourage a slow driver turning speed of 5-10 mph.
The last, element of a protected intersection is the use of bicycle specific signals and bicycle-friendly signal phasing. Just as important the physical design of intersections is the use of signals to control how and when different people can proceed. At its most secure, a protected signal phase for bicyclists will use red signals to prevent any conflicting car turning movements. There is no risk of right or left hooks from cars when they are prohibited from turning while bicyclists are traveling through.
[Protected Intersection:] Source: LYBIO.net
A variation of the protected signal phase is to give all car movements a red signal, and all bicyclist movements a green.
This simultaneous green phase gives full rein of the intersection to bicyclists, allowing through movements in all directions at once, left turns in one stage and even full U-turns through the intersection. Even at high-volumes, bicyclists are good at negotiating shared space and will have no trouble staying out of each others way.
When it is not possible to prohibit conflicting movements entirely, an alternate approach is to provide a leading bicycle interval. This is a head-start green light for bikes of anywhere from 2 to 5 seconds. It provides them a little extra time to get rolling, enter the intersection, and maybe even clear it completely before people driving start to move.
Taken together, these design elements create a safe, clear experience for all people using the street. Signals control movements, refuge islands create protected spaces, and proper positioning of crossings and conflict points provides everyone with the time and space necessary to react to potential risks.
While the protected intersection design is unconventional and nonstandard in the U.S., so were protected bike lanes only a few years ago.
Using these design concepts, planners, designers and engineers can bring the protection of their bike lanes into the space where people need it the most, and finally provide a safe place for people of all ages and abilities to ride.
Learn more online with footnotes and references at protectedintersection.com.
This proposal for the George Mason University 2014 Cameron Rian Hays Outside the Box Competition presents a vision for a safe, clear intersection design that improves conditions for all users. Proper design of refuge islands, crossing position and signal timing can create a safe intersection that people of all ages and abilities would feel safe in. Learn more online at ProtectedIntersection.com
Protected Intersections For Bicyclists. Provide a safe place for people of all ages and abilities to ride. Complete Full Transcript, Dialogue, Remarks, Saying, Quotes, Words And Text.