Part 3: Before you build it...

By David Gleason

On your commute to work or on a trip to the store, you might spend only minutes in a bike lane. While it might seem like a simple construct, that bike lane took months or even years for it to become a reality.

The truth is bike lanes can’t go just anywhere. There are specific engineering requirements that must be met before you enjoy your reserved slice of road.

It is often asked why a bike lane can’t be simply striped on a road like Ashland or Western avenues. Why can’t a crew go out, put down a stripe and call it a bike lane? Many factors are considered when designing bike lanes – existing roadway geometry, parking, land use, bus and truck routes and pavement conditions just to name a few.

The short answer, however, is there often isn’t enough roadway width. Vehicle travel lanes, bike lanes, and parking lanes have standard minimum lane widths, and many roadways don’t have the necessary width to install a bike lane.

The minimum lane width standards in Chicago are:

• 10 feet for a travel lane for motor vehicles
• 5 feet for a bike lane
• 7 feet for a parking lane.

For a typical two-lane, two-way road with on-street parking on both sides, that adds up to 44-feet from curb face to curb face. Add in a couple more travel lanes on a high-volume roadway, and at least 64-feet is required.

That doesn’t mean you can’t ride a bike on roads that aren’t wide enough for a bike lane.
There are plenty of City roads that are suitable for cycling: portions of Lawrence (60 feet), Lincoln Avenue (42 feet), Milwaukee Avenue (42 feet), 33rd Street (38 feet), 59th Street (42 feet), or 83rd Street (42 feet) are suitable but don’t have the necessary width to install a bike lane.

Just because a street initially is not wide enough for bike lanes doesn’t mean nothing can be done.

Options

Parking removal. Some cities will remove parking to accommodate the space for a bike lane. That, however, can be very controversial especially for the car-parking population.

Road diets. Another option is to remove travel lanes on multi-lane roads through the use of a “road diet” or “4-to-3” conversion. In this scenario, one travel lane is removed in each direction on a four-lane road and replaced with a center turn lane and bike lanes.

There are requirements for this kind of change, as well.

• The Average Daily Traffic (or ADT), as an initial guideline, shouldn’t be higher than 19,000 to 21,000 vehicles per day. Just to give you an idea, Western Avenue in Chicago is in the 23,000 to 40,000 range and Sheridan Road is around 36,000 vehicles per day.
• The Level of Service (LOS) is another gauge of a road diet’s viability. It measures the delay a vehicle experiences while trying to pass through an intersection during a typical rush-hour. The standard minimum for an urban setting is LOS D (LOS A is the best), which represents up to 55 seconds of delay. Reducing the number of travel lanes reduces the number of vehicles that can pass through an intersection on a given green light and also increases the queue of vehicles waiting to get through an intersection. In the worst case, an excessive queue can lead to total gridlock for an area.

Marked shared lanes. One way the City of Chicago has adapted to narrow streets is to use marked shared lanes. Unlike a bike lane (which is marked with two stripes, a bike symbol and an arrow), a marked shared lane is marked only by a single line at the edge of parking), a bike symbol and a chevron. Unlike a bike lane, a marked shared lane is not for the exclusive use of bicyclists. It is intended to raise driver and bicyclist awareness about sharing the roadway.

• Marked shared lanes can be installed on narrower roadways (e.g. a 42’ rather than 44’ roadway,) such as Milwaukee and Lincoln, and since marked shared lanes usually don’t impact the number or width of existing travel lanes, they are often exempt from the rigorous review that bike lanes must go through.

Approval

The final hurdle to installing a bike lane is the approval process, which, depending on jurisdiction, passes through multiple offices and agencies. At an absolute minimum, the Chicago Department of Transportation must approve the bike lane. Depending on the kind of street or in what local or state jurisdiction it lies, other agencies may need to approve the design. After the final engineering approval is attained, one more major approval is required from the respective city aldermen.

Ta-da!

This process of data collection, design, engineering, review, and approval can take up to two years to complete, but once it’s done, the project picks up speed quickly. The project moves into advertisement and bidding, contract approval and finally construction and before you know it, ribbon cuttings are taking place on new bike lanes in Chicago.

David B. Gleason is a traffic engineer employed by the Active Transportation Alliance. He consults full-time to the Chicago Bicycle Program where he serves as the Managing Bikeways Traffic Engineer in charge of on-street bikeways. Locally, he sits on the Mayor’s Bicycle Advisory Council. He sits also on the Bicycle Technical Committee and the Pedestrian Task Force within the National Committee on Uniform Traffic Control Devices. He has been commuting year-round by bicycle for 10 years.