There's More than One Way to Skin a... Protected Bike Lane!

The SketchUp practice continues... and this time looking at the many ways to retrofit protected bike lanes without digging up the entire street. Of course anything can be done with enough money, but rarely is there enough money to provide the "Cadillac" solution, so it's important to consider different solutions...
​

The Existing Condition

Starting with a four lane roadway with no bike lane, two lanes shown here to the crown in the centre of the roadway, how are we going to retrofit a protected bike lane in here assuming it was overbuilt and we can reduce it back down to two lanes? Key pieces of information are that we have a sidewalk that drops at 2% to the curb, and a roadway that drops at 2% to the gutter, typical values to enable both to drain to catch basins installed in the curb and/or gutter.
​

The Raised Bike Path

The first thing we might want is an off-street bike path, i.e., located above the roadway and separate from it. So we continue the 2% grade from the curb, because it still needs to drain to the roadway, and because we're dropping the bike path grade as the roadway grade underneath is rising, at some point we're going to meet. In this example we don't quite meet, we have just enough difference in grade to add a mountable curb. To add a full height curb we'd have to reprofile the roadway or remove and rebuild the sidewalk and a higher elevation with associated costs and access issues. We've built over the existing catch basins and therefore must install new ones, and as we're raising the elevation of the bike path, this increases the amount of new material we must use. We have no grade separation between cyclists and pedestrians enabling either to more easily enter the others space. This may or may not be an issue subject to volumes, and where volumes are higher consideration should be given to some form of vertical separation if space permits. With just a mountable curb separating vehicles from cyclists, errant vehicles can enter this space more easily whether unintentionally as a result of distraction or a collision, or intentionally to "stop temporarily" or as we otherwise call it "parking". We could reduce the cross slope off the bike path to 1% increasing the mountable curb from ~30mm to 60mm, better... but still mountable.
​

The Full Height Raised Bike Path

We can address the issues of vehicles entering the cyclists space by adding a full height curb between the bike path and vehicle lanes, but this creates a drainage issue with water falling on the bike path now flowing into a valley between the sidewalk and bike path. We can fix this by installing some form of trench drain between the two. We'll also still need new catch basins to manage drainage for the roadway. This option still offers little separation between pedestrians and cyclists, and again subject to volumes may or may not be an issue.
​

The "Inbetween" Bike Path

We could also call this one the Copenhagen. Its not too different from the infrastructure there. In this case we have a 30mm drop from the sidewalk to bike path and 30mm drop from the bike path to roadway. So vertical separation for all modes, but very limited, and definitely mountable by a vehicle. I'm not sure drivers in North America would be as aware or respectful of this new slightly elevated space being for cyclists only. Like Copenhagen, I didn't provide any buffer space, meaning this is a wide facility with plenty of space to pass, but to the untrained eye, again in North America, this might look little different to a vehicle lane to some. Richmond, BC provides something similar using mountable curb, but with narrower lanes. In my experience, I didn't feel much more protected there than with a painted lane. 
​

The On-Street Protected Bike Lane

And finally, the humble on-street protected bike lane, constructed simply with concrete median island pinned and/or keyed into the existing asphalt roadway, a lower cost solution that greatly reduces the amount of construction required (assuming the roadway pavement is in good condition). Breaks can be added to allow drainage from the roadway to existing catch basins. Breaks can also be added to facilitate access to the bike lane from minor streets or business accesses, whereas the full height curb options would require a formal letdown, Whatever the purpose, these breaks can reduce the amount of concrete required and the cost, and overall the cost of this option is much cheaper than those above allowing a larger protected network of bike lanes to be constructed more rapidly.
​

The Coronavirus Protected Bike Lane

This seems relevant right now, but it's also a sign of how easily we can create protected bike lanes. With traffic much lower, and walking and cycling much more popular, now is the time to try things!

What's your preference? How else might you skin a retrofitted protected bike lane into a street without digging up the entire thing?