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Lane Reduction:
Some roads have more travel lanes than necessary and are difficult to
cross because of their width. Reducing the number of lanes on a multi-lane
roadway can reduce crossing distances for pedestrians and may slow
vehicle speeds. A traffic analysis should be done to determine whether
the number of lanes on a roadway (many of which were built without such
an analysis) is appropriate. Level-of-service analysis for intersections
should not dictate the design for the entire length of roadway. For example,
a four-lane undivided road can be converted to one through lane in
each direction, with a center left-turn lane or with a raised median,
and turn pockets and bicycle lanes on both sides of the roadway. Turning
pockets may be needed only at specific locations.
Depending on conditions, it may also be possible to add on-street parking
while allowing for bicycle lanes on both sides of the street—instead
of a center turn lane. If no sidewalks exist along the roadway, these should
be added. If sidewalks exist, and there is adequate room, a landscaped buffer
is desirable to separate pedestrians from the travel lane.
A typical three-lane configuration consisting of two travel lanes and a two-way left-turn lane (TWLTL) also has advantages for motorists. Through traffic can maintain a fairly constant speed, while left-turning drivers can exit the traffic stream and wait in the TWLTL. However, TWLTLs can also create problems for opposing left-turn vehicles and may be used as acceleration lanes by some motorists. Designs that incorporate raised medians and left-turn bays may offer a better solution.
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| Photo by Cara Seiderman
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| This street in Cambridge, Massachusetts, was reduced from four lanes to three. The conversion introduced wider sidewalks, additional space for landscaping, street furniture and cafes, and bicycle lanes. |
• Remedy a situation where there is excess capacity.
• Provide space for pedestrians, bicyclists, and parked cars.
• Reduce crossing time, which can help optimize signal timing.
• Improve social interaction and neighborhood feel along the street. |
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• Roadway capacity operation and overall road safety need to be considered
before reducing the number of lanes.
• Ensure street connections so major arterials can be crossed at controlled
intersections. |
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The cost for restriping a kilometer of four-lane street to one lane in each direction plus a two-way, left-turn lane and bike lanes is about $3,100 to $12,400 ($5,000 to $20,000 per mile), depending on the amount of lane lines that need to be repainted. The estimated cost of extending sidewalks or building a raised median is much higher and can cost $62,000 per kilometer ($100,000 per mile) or more.
If a reconfiguration is done after repaving or with an overlay, and curbs do not need to be changed, there is little or no cost for the change. |
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