Narrow on street bike lanes
Some municipalities or civic activist
feel the are helping bicyclists by striping bike lanes that are less then
minimums. This puts riders to close to car
doors. Bicyclist who move out to the motorized traffic lanes annoy
drivers who think the riders should be in what is clearly marked as bike
The following discussion-group note
clarifies AASHTO misunderstanding's
Your statement that AASHTO recommends a minimum combined width of 11 feet for a parking lane plus a bike lane is essentially incorrect. The 11-ft minimum only applies to roadways without curbs (aka open-section or rural-section roadways). For roadways with curbs (aka closed-section or urban-section roadways), such as Union St, the *minimum* combined width recommended by AASHTO is 12 feet. Apparently, when there is no curb present, cars are typically parked closer to the right edge of the pavement.
Also, as do you note, AAHSTO further recommends *at least* a one-foot wider combined space where parking density or turnover is high such as on Union St. IMO,
the AASHTO recommended minimums are only acceptable where parking is sparce and parking turnover is infrequent.
As I recall, some of the drawings in the 1999 AASHTO bikeway guide are poorly labeled or mislabeled, leading to the impression that AASHTO's minimum recommended combined width is generally 11-ft, not 12-ft. The text for this section of the AASHTO guide states these recommended minimums correctly.
Because opened car doors can extend from 35" to 45" to the left of the parked vehicle, and a bicycle and its rider is about 24" wide, safe cycling beside a line of parked vehicles requires keeping one's wheels at least five feet to the left of parked vehicles at all times. The parked vehicles themselves typically extend at least seven feet from the curb face, so it is unwise to cycle with one's wheels within 12 feet of the curb wherever there is dense curbside parking.
When the AASHTO bikeway guide states an absolute 12-ft minimum width (which is clearly inadequate for Union St), a half-foot narrower width is most certainly
unacceptable. The City should remove these dangerous substandard bike lanes at once.
Source: Allen Muchnick Arlington VA
Width occupied by parked motor vehicles, by John S. Allen (as shown by the
chart, the door zone extends at least 10 ft from the curb when vehicles are parked only 6" or 8" from the curb
Wayne Pein's critique of door-zone bike lanes:
Critique of various bicycle facilities, including door-zone bike lanes, by
direct riding against traffic
Some roads have a bi-directional
multi-use trails along busy sections of a highway that frequently cross
side roads or the entrances to business's. Drivers turning
right, look left for a gap in the traffic flow and go when they see
it. At walk speeds pedestrians tend to notice the lack of
eye contact but the faster speed of bicyclists evasion response
Where there are frequent crossings,
recommend sidewalks on both sides of the highway of co-equal width and
bike lanes or wide outer lanes that allow cyclist to travel the same
direction as the motorized traffic.
Lanes that cut-off a motorized
||On the left is a bike lane heading
south along South Hayes Street in Arlington VA. Note there
are 3 traffic lanes to the left of bike lane. Pentagon
City Mall is to the right of photo.
Note in the 'looking north view' the bike lane cut's
off the motor vehicle lane. The bicyclist is being directed
to cut in front of a moving motor-vehicle. The Auto-traffic
is expected to either shift to a new lane to the right of the bike lane
or to move what had been the middle traffic lane. Interestingly
the dash-lines for the shift come at the same point the bicyclists is
directed to the left.
In the photos above, both a truck and a car maintain their
alignment to the adjacent motor vehicle traffic lane rather then shift
to the traffic lane to the right of the bike lane. Note the
bike lane is directly under their vehicles.
|To the right we see the
truck (from the photo above) has pulled up to car waiting for a
traffic light.. The bike lane is directly under the
car. Both the car and truck continued south in the right