Special lane markings alert drivers to slow down and guide cyclists to a safer spot.
In the late 1990s, bicycle lanes were painted on streets in northwest Portland, a high-density neighborhood less than a mile from downtown. But congestion at traffic lights made reducing space for automobiles impractical in some areas. As a result, the project left a nine-block gap in the bike network.
Caught between the need for a continuous bike lane and the demands of drivers, Portland transportation engineers finally came up with a solution. Next month, the city will fill the gaps in the network with new shared-lane pavement markings, called "sharrows." Stencils of a bicycle with two chevron markings above it will be painted, two per block, in areas too narrow for a bike lane. The idea is to keep cyclists away from parked cars while promoting awareness of their right to use the road.
"The sharrow sends the message to cyclists, 'yes, you are welcome here,' " says Mia Birk, a principal with Alta Planning + Design in Portland and lead author of a recent study on shared-pavement markings in San Francisco.
Pioneered in Denver in the mid-1990s, sharrows are attracting the attention of transportation officials around the United States. But the markings are controversial. In June, Boulder, Colo., became one of the few cities outside of California to install the shared-lane markings; that same month, sharrows were rejected by the National Committee on Uniform Traffic Devices, an organization that sets national traffic standards.
"We have a litigious society," says Ms. Birk, explaining the challenges of implementing bike-friendly street designs. "It takes a progressive traffic engineer to say 'I'm comfortable enough to take a risk.' "
Some cycling advocates say sharrows will preempt the installation of bike lanes, which often entail hard-fought battles to remove a car travel lane or on-street parking.
"Once sharrows are accepted, they will become the preferred solution," says Kevin Jackson, who sits on the Bike and Pedestrian Committee in Sunnyvale, Calif. "Not because they are better, but because they are politically expedient."
The principle behind sharrows is simple: They reinforce existing rules of the road. In most states, cyclists are required to stay as far to the right as possible, except under unsafe conditions. One of these conditions is when the travel lane is too narrow for side-by-side passage of an automobile and a bicycle.