A new bike box on St. George at College St has been in place for about 6 months now.
Painting the Town Green
Why has green paint been popping up all over Toronto?
dandyhorse contributor - and engineering professor - Jun Nogami found out out more about this bright new addition to our city's bike infrastructure mix.
It's all about reducing bike/car conflict. This marking on Annette at Dundas St. West provides a spot for bikes to stop while still allowing cars to make a right turn. The green markings extend across the intersection to help indicate the right-of-way for cyclists.
Green “paint” is starting to be a common feature of bike infrastructure across the city of Toronto. It is being used to make bike infrastructure more visible to both motorists and cyclists. At the same time, some people have raised concerns about whether or not the green paint reduces traction, especially when the road is wet. We decided to find out a little more about the green markings. Jacquelyn Hayward Gulati, the City's acting director of transportation infrastructure management, was kind enough to answer our questions.
Interview and photos by Jun Nogami
What is the formulation of the green pavement markings?
They are thermoplastic, which is a Ministry of Transport Ontario-rated durable marking, available in high-friction/anti-slip formulations.
Has there been any attempt to improve traction of the green areas, such as mixing in sand or something similar?
Our specification includes pre-mixed Corundum and topically applied Corundum, ensuring a high level of high-friction/anti-slip performance throughout the life of the material. Corundum is commonly formulated in sandpaper and has been more durable than silica/sand. [Ed's note: Corundum is aluminum oxide, with the same composition as sapphire, with a hardness of 9 on Mohs scale. Sand is silicon dioxide or quartz, which has a hardness of 7.]
Are bike lane markings a similar paint or material?
Solid lines and symbols are done in cold plastic, which is not formulated with Corundum. Instead, glass beads are pre-mixed and topically applied for retro-reflection.
Does the city have any data on whether these markings are slipperier than asphalt?
An aggressive new test formulation [of the green markings] has been found to be too abrasive, potentially causing injury to fallen cyclists. Depending upon the age of the thermoplastic, it may start off slipperier than asphalt when new and as it wears it becomes more skid resistant as the embedded Corundum is exposed. However, overall, the product is often slipperier than asphalt when first applied. BUT, this is similar to cold plastic and paint pavement markings.
[Ed's note: independent testing has shown that white markings such as those on a cross walk are more slippery than pavement, whereas the green markings can provide traction comparable to asphalt.]
What is the expected lifetime of the green markings versus standard road markings?
Thermoplastic lasts five years on asphalt versus one year on concrete. The City is currently testing thermoplastic on scarified [roughened] concrete this year in order to improve life span. Cold plastic is a minimum of three years depending on traffic and location. Thermoplastic and cold plastic have almost equal hardness factors, with cold plastic being slightly harder than thermoplastic. Durable markings, as tested by the MTO, will out-perform all paints during their respective lifespans.
This bike box on Harbord at Shaw is two years old. The markings are holding up well, although the green colour has faded a bit.
Has the city considering using coloured asphalt, as has been done in several places in Europe?
Coloured asphalt is very expensive and involves special mixes at the asphalt plant and is not cost effective in small batches. We have used impressed, or dyed, asphalt at level crossings (such as Rockcliffe Blvd. in 2016 and on several trail crossings in Scarborough, Shops at Don Mills).
How does the city decide where green paint is appropriate?
[We use this infrastructure] to alert drivers to presence of cyclists [which includes places like] conflict areas, such as transit stops, intersections, safety improvements, traffic moving in multiple directions.
Where might we see more green paint in 2017?
The following locations are being considered:
• Bay and Queens Quay
• Bayview / River
• Don Roadway / Lake Shore E
• Dundas / Lansdowne
• Shuter / Church
• Lower Simcoe / Queens Quay
• Harbord / Ossington
• St. Dennis
No, it shouldn't affect the performance of induction loops.
How much does it cost to apply the green markings?
It can be $1,000 for a small bike box, and up to $20,000 for a complete intersection, depending on the total area covered and other parameters.
So it would seem that the City is taking a thoughtful approach to using the green markings to improve the effectiveness of bicycle infrastructure. It turns out that putting in a bike lane is much more than just putting down some white paint.
Sidebar: I did some simple measurements of traction on white crosswalk markings and green markings versus pavement by dragging a force sensor mounted on a platform with rubber feet on the bottom. The measured force indicates the amount of friction that would roughly correspond to what a skidding bike tire might experience.
Here is a picture, below, of the platform being dragged on a green marking.
In this case, there was no significant difference in friction between the green marking and the pavement. However, when we repeated this test on a crosswalk, the data shows that the white marking provides about 20 per cent less traction than the pavement. Both measurements confirm the information that was provided by the city.
For more details of our testing go to:
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