December 21, 2015

Twelve Days of Bicycles - Eight Curbs A Calming

Originally developed in the Netherlands, protected intersections – consisting of four traffic islands and forward stop lines to guide cyclists safely – have recently started to gain ground in North American cities as a complement to separated bike lanes. While not yet introduced in Toronto, local cyclists there are already calling for protected intersections and Mobycon hosted an intersection design workshop on October 2, 2015. To get a Toronto perspective on protected intersections, I interviewed George Liu, MES (Pl), a Statistics Research Assistant with the Toronto Cycling Think & Do Tank and Masters Candidate in Human Factors Engineering who attended the workshop.
A simple sketch of what a protected intersection looks like
RZ: When did you first become aware of protected intersections and what prompted your interest in them?
GL: In 2013, I did a cycling tour in Europe, where protected intersections were used in the Netherlands. Being an urban planner, I was curious about the design of these fantastic intersections. After the tour, I saw a YouTube video explaining the operation of protected intersections. What a great idea! Today, I study how to apply human factors engineering to road [and intersection] design in order to facilitate interactions between different road users.

RZ: Are there Toronto specific challenges to adopting protected intersections?
GL: Leaving adequate turning radii for trucks is a challenge when designing intersections. However, if we design all intersections with large turning radii for tractor-trailers, then smaller passenger cars will turn at higher speeds; resulting in increased danger to pedestrians and cyclists. One of the solutions is installing protected intersections with mountable corner aprons that can accommodate turning trucks while reducing the effective radius for smaller vehicles.
A diagram explaining the difference between curb & effective radius
SOURCE: Institute of Transportation Engineers
RZ: Tell me more about the impact of turning radius.
GL: On a street without bike lanes, motor vehicles have to use the curb turning radius to turn right. When painted bike lanes are present, the effective turning radius for motor vehicles becomes larger because they are set back from the curb. When making a right turn, the driver tends to “cut the corner” and encroach on the bike lane. Bike boxes – which set the car further back – worsen this particular problem by encouraging an even larger turning radius. Protected intersections, however, force the driver to make the slower, sharper turn as with the base scenario without bike lanes.
Turning radius applied to Harbord & St. George (via Google Maps)

Red - Curb, Light Blue - Bike Lane, White - Bike Box, Green - Protected Intersection
RZ: Which intersection(s) would you recommend to do a pilot protected intersection?
GL: A pilot should be done at intersections with bike lanes on all approaches and more than one motor vehicle lane in each direction. Harbord and St. George (near the University of Toronto) is a good choice, given the presence of dual-lane bike boxes. While a one lane bike box is safe, a dual-lane bike box requires cyclists to cross one motor vehicle lane to make a left turn (a.k.a. vehicular cycling). This lane change maneuver requires cyclists to exit the bicycle lane before the intersection; creating conflicts with motor vehicle traffic.
Current situation at Harbord & St. George
Together with protected intersections, the addition of pedestrian islands will enable shorter crossings on wider streets. Pedestrian islands allow pedestrians to negotiate traffic conflicts in stages – one or two lanes at a time. These measures need to be accompanied with increased driver and cyclist education in order to make such intersections a reality.

RZ: What other intersection remedies are relevant to Toronto?
GL: In the event protected intersections are not present, the bike lane should be extended across the intersection with green paint. This informs drivers where cyclists are expected to cross and will reduce vehicle encroachment on bike lanes while queuing for right turns.

Right turns on red will be improved with protected intersections, in which the island provides enough space for a car to wait for through motor vehicle traffic while keeping the bike lane and sidewalk clear. If right turns on red are prohibited, a delayed green will allow pedestrians to cross before drivers make the initial rush to turn ahead of pedestrians

In summary, tight turning radius should be designed such that interactions between motor vehicles and pedestrians or cyclists occur as close to 90 degrees as possible to provide the best sight lines. Staged crossings should be used to manage one conflict at a time. Last, but not least, lanes should be narrower to slow down traffic and decrease pedestrian crossing distance; something the City is currently investigating.

RZ: What project are you currently working on for your Master’s thesis?
GL: For my Master’s thesis, I am designing a study to measure the elevated driver workload intensity associated with searching for on-street parking. My hypothesis is that drivers searching for parking pose additional danger to themselves and other road users. Donald Shoup, professor of urban planning at UCLA and author of “The High Cost of Free Parking”, advocates setting the price of on-street parking so there is an open spot on every block to minimize the dangers associated with “cruising for parking”.

At the time of writing, Alta Planning in Portland, Oregon recently unveiled a document explaining the protected intersection concept and evolution in greater detail. Six North American cities, including Vancouver and Montréal, introduced protected intersections so far. Since Cycle Toronto built a temporary bike lane at Open Streets in September, maybe they could build a temporary protected intersection for their next project?

Protectively yours,
Rob Z (e-mail)

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