Solving the Lynn Street/Lee Highway Bike/Car Conflict

The intersection of Lee Highway and Lynn Street in Rosslyn, where the Custis Trail crosses Lynn St., has been the subject of great scrutiny lately. (GGW reported on a recent meeting at this very intersection.)  This is one of the most dangerous intersections for cyclists in the Greater Washington area. By reconfiguring the exit ramp for the Key Bridge, this conflict can be entirely removed, dramatically improving safety while also potentially improving traffic flow.  (This post has been cross-posted at Greater Greater Washington, including a number of reader comments.)

The problem at this intersection is traffic turning right from the I-66 off-ramp onto Lynn Street traveling towards the Key Bridge.  This traffic has a green light at the same time as the pedestrians and cyclists have the cross signal. There are two lanes of right turning cars (and sometimes cars in the third lane turn right illegally). By shifting the Key Bridge traffic to the north of the Custis Trail crossing, this conflict will be eliminated.



This diagram shows a potential redesign that can significantly improve the situation for all users: bikes, peds and cars.  The numbers below correspond to the red numerals on the diagram.

1. Split I-66 offramp: Currently the I-66 exit ramp is one lane that curves up to Lynn Street, dividing into three lanes as it approaches Lynn. The right lane is right-turn only, the middle lane is right turn or straight onto Lee Highway, and the left lane is straight only.
My proposed configuration would divide the ramp just after its split from I-66. Lee Highway traffic would follow the existing ramp up to the light at Lynn Street. Traffic headed for the Key Bridge would curve down under the existing Custis Trail ped/bike bridge over the GW parkway and then curve left to join the existing Key Bridge ramp from the southbound Parkway.

2. Reconfigure southbound offramp intersection: The combined Key Bridge ramps could be reconfigured into a 90-degree intersection at Lynn Street with a traffic light. While I proposed all three lanes to be right turn only, the far left lane could potentially allow movement onto the ramp for the northbound GW Parkway. This intersection would have no-right-turn-on-red restriction, which would eliminate the current conflict for cyclists and pedestrians also headed for the Key Bridge.
Cyclists and pedestrians could cross with the Lynn Street traffic while it has the green, and would wait with the Lynn St. traffic while the ramp traffic has the green. With three right turn lanes and no time lost yielding to bikes and peds, there could easily be an increase in capacity for cars, even with right turns on red prohibited. In evening hours, right-on-red movements could be allowed from the right-most lane only.

3. Narrow existing Lynn/Lee offramp: The existing ramp/Lynn St. intersection can then be narrowed to two lanes, allowing more space for the trail, improving sight lines, and reducing crossing distances. Both lanes would be straight only onto Lee Highway. This would completely eliminate all conflicts with Custis Trail traffic, since there would be no turning cars. Lee Highway and Custis Trail traffic would cross on the green and would wait on the red while Lynn Street traffic proceeded.

Additional notes:

- The ped/bike bridge appears to be wide enough to accommodate one ramp lane if all the space is used, including shifting the current GW lanes over and using the median.  I'm not an engineer, but if that is possible, then this solution allows for eliminating the conflict without the need for significant additional infrastructure like a tunnel.

- A permanent solution like this one is eventually going to be necessary.  The conflict at this intersection can only get worse.  Bicycle use is increasing rapidly, and both DC and Arlington are promoting more cycling and investing in it with Capital Bikeshare and other efforts.  As bike traffic increases, the right turning cars will become more and more frustrated by having their travel impeded, and conflicts will escalate.

- The redesign also would nicely complement the N. Lynn St Esplanade and Lee Highway/Custis Trail improvement project that is currently being planned (note upcoming meeting on October 5).