Bikeway Design Guide

After two years of work, the National Association of City Transportation Officials released an Urban Bikeway Design Guide. This online resource is meant to help transportation officials design better bike facilities in the United States.

The Status Quo

The new Bikeway Design Guide consolidates guidance already available in the AASHTO Guide for the development of Bicycle Facilities (1999 edition) and in the Manual on Uniform Traffic Control Devices (2009 edition).

The American Association of State Highway and Transportation Official (AASHTO) “Green Book” is holy writ for American highway engineers; to deviate from its standards means risking lawsuits for the engineer, the planning firm he works for and the government agency using his services. Engineers have learned over time to be risk averse, since novel innovations that might look good on paper can lead to an increase in risk for people on the ground. Even if there is no real increase in risk, innovations are often magnets for lawsuits. A lot of these senior engineers were around during 1970s bike boom and might have been involved in the bike facility experiments back then. Like today, enthusiastic advocates pushed innovations like buffered bike lanes but the engineers who designed the facilities were horrified after they resulted in a significant increase in cyclist injuries and deaths.

AASHTO sharrow

Still, AASHTO had to be encouraged to update their old Bicycle Design Guide after Congress added a bike access requirement for Federally funded highway projects with TEA-21 in 1998. At the request of the Federal Highway Administration, state and local agencies, and bicycle lobbying groups, AASHTO created the 1999 guide. Last February, AASHTO published a draft of an updated guide for review by the Technical Committee on Nonmotorized Transportation.

The MUTCD (Manual on Uniform Traffic Control Devices which defines road signs and pavement markings) story is a little different. They’ve long had input from day-to-day cyclists who are also civil engineers. Their problem is their proposals are often voted down by the majority. Many knowledgeable cyclists complain that placement guidance for sharrows and bike lanes in the MUTCD don’t go far enough in ensuring cyclist safety, but even putting them in the MUTCD was a result of compromise and negotiation. Given all of this and the five to six year process of issuing updates, change happens very slowly.

AASHTO contraflow bike lane

Innovative Bicycle Facilities

NACTO’s new bicycle design guide makes the standard bike facility designs easy to access for any traffic engineer. The officially recognized bike facilities are conventional bike lanes and some signage, but even this is good because the number of ways these facilities can be screwed up is near infinite. The cross sections and other diagrams from AASHTO and MUTCD are necessary for proper design, but the illustrations created for NACTO’s new guide really help people visualize what a bike facility will look like.

NACTO bike lane diagram

The part that many cycling advocates are really excited about, though, is the inclusion of non-standard bike facilities in this guide.

In the world of bike lanes, there is no official guidance on the design of buffered bike lanes, contraflow bike lanes, or even left side bike lanes for one-way roads. Intersection treatments such as bike boxes, bike lane crossing markings and so forth help remind motorists crossing through the intersection that bicycles are traffic, too.


One of the driving forces behind AASHTO and MUTCD is to standardize road design and signs across the United States. We all have an expectation of how freeway ramps work, and we all know what the various road markings and signs mean. With the recent proliferation of bike facility experiments, NACTO hopes their bike design book becomes an online resource to encourage standardization across the United States and to share experiences on what works best. For colored bike lanes, for example, a number of colors are being applied, but green is becoming the color of choice “to minimize confusion with other standard traffic control markings.”

NACTO bike box

The new guide brings a lot of detail and flexibility for bike facilities that already exist in the mature highway design manuals. Participating city planners published this new guide partly in the hope of pushing MUTCD and AASHTO to adopt these guidelines that they’ve been slow to accept so far.

According Streetsblog, the states of Washington and Texas are already looking at accepting this new NACTO bikeways guide as an official design standard on top of AASHTO and MUTCD. (Doing so would require an act of their respective state legislators – road design standards are a part of state law).

In the meantime, remember that the non-standard facilities are likely not legal in your state. That doesn’t stop some large cities from pushing ahead anyway, but it’s enough of a hindrance to hinder most local public works departments. Most states do have a process, however, to apply for waivers and approvals for ‘experimental’ road designs and markings.

Bike lanes across freeway interchange

AASHTO Bicycle Facilities Guide 2010

AASHTO does have an updated bicycle design book in the works. A draft was published for review in February 2010 that addresses many shortcomings missing from 1999 guide, and includes many of the concerns that are also addressed in NACTCO’s new bicycle resource such as contraflow bike lanes, left-side bike lanes on one-way streets, and traffic signals (both detection of cyclists and green crossing time).

AAsHTO’s new guide also includes numerous situations not covered in NACTCO — bike lanes at freeway ramps, across railroad crossings, and through roundabouts. An entire chapter is devoted to bicycles and traffic calming facilities, in which a street diet treatment impact to cyclists is evaluated. The 2010 AASHTO draft covers one of my bugaboos, that “The routine use of bollards and other similar barriers to restrict motor vehicle traffic is discouraged, unless there is a known history of use by unauthorized motor vehicles.  Barriers such as bollards, fences, or other similar devices create permanent fixed object hazards to path users.  Bollards on pathways are often struck by cyclists and other path users and can cause serious injury.”

AASHTO’s bike design 2010 edition even provides recommendations for bike facility drainage, pavement maintenance, snow clearance, and works — all areas that are routinely ignored.


  1. Looks like a lot of talk about wide roads that could help, but around here, the space is lacking, and we need innovative ways to have cyclists using the road safely. I’m trying to get it more standard that hills have the yellow line shifted closer to the downhill lane, so that even when there’s no room for a bike lane, it could at least be more like 14ft uphill and 12ft downhill, in hopes that going uphill, it gives more room for cars to pass a slower cyclist, and going downhill, the cyclist should take control of the lane since there isn’t sufficient room to pass. Or maybe these documents also explain that… I’ll read through it later.

  2. If you have 14+12= 26 feet of total road space, as in your example (excluding parking or sidewalks), you could have 10 foot lanes with a 6 foot bike lane on the uphill side, and sharrows on the downhill side.

    10 foot lanes are standard on streets in my city that are getting bike lanes, and are wide enough even for buses and trucks.

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