Posts about Custis Trail

This map shows the locations of both the original bridge and the new bridge, which is planned for a mid-March completion, as well as the estimated placement of the new trail connector.

The old bridge is at the yellow marker, the new bridge at the pink marker. Image from Google Maps. Click for interactive version.

A significant area of asphalt will be removed and replaced with landscaping. The total amount of permeable surface is likely to be increased even though the new bridge and trail connector will be wider than the original.

The new bridge has an estimated lifespan of 75 years and will be 50 feet long and 14 feet wide with a concrete deck (the existing bridge has a wooden deck). Half of the $240,000 cost is covered by Arlington's bridge replacement funding, while the other half comes from the pedestrian improvements budget.

This intersection has received a lot of scrutiny lately, after a driver sideswiped a cyclist who was subsequently blamed for the incident by Arlington Police.

The primary problem at this intersection is traffic turning right from the I-66 off-ramp onto Lynn Street to head toward the Key Bridge. This traffic has a green light at the same time as the pedestrians and cyclists have the walk signal. There are two lanes of right turning cars (and sometimes cars in the third lane turn right illegally). Shifting the Key Bridge traffic to the north of the Custis Trail crossing could eliminate this conflict.

According to recent counts, the intersection sees more than 400 bikes an hour during rush hours, and that number is increasing. That is one bike about every 9 seconds on average.

My proposed redesign could significantly improve the situation for all users: cyclists, pedestrians and drivers. The numbers below correspond to the red numerals on the above graphic.

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.

It appears that there is probably enough room under the existing bike/ped bridge to accommodate a new ramp lane without lengthening the bridge. This Google Street View shows the southbound lanes of the parkway traveling under the pedestrian bridge.

Image from Google Street View.

Note there is space on both sides of the lanes (the far support is about six feet beyond the stone wall if that additional space were needed.) The new configuration would have one lane of traffic traveling north as it passes under the bridge in addition to the Parkway lanes, which would be shifted into the existing median.

I paced it off, and my best estimate is 58 feet of span available between the support wall on the west and the support column in the median of the Parkway. That would accommodate three 12' lanes with 22 feet for shoulders and 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 bike tunnel.

While this may seem like a costly proposal, 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 number of conflicts with right turning cars will no doubt increase with it.

The redesign also would nicely complement the N. Lynn St Esplanade and Lee Highway/Custis Trail improvement projects that are currently being planned. A meeting on these projects is scheduled for tomorrow night.

Whatever the solution, the northern portion of Rosslyn will need major updates to its traffic patterns in order to accommodate a growing number of cyclists and pedestrians in an environment that was originally designed for the convenience of motorists.

While engineering improvements are at least two years away, Dennis Leach, the Arlington County transportation director, promised his staff would further investigate in the upcoming week at least two of the suggestions that arose tonight regarding marking and signage.

One participant suggested painting the crosswalk wider and madke it more prominent. For signage, another suggested modifying the crossing signal to include a bicycle shape. This will help to alert drivers to expect both pedestrians and cyclists. Arlington could potentially implement both in the immediate term.

Photos from yesterday's event by the author.

In the longer term, the Arlington County Division of Transportation team discussed future design changes to the intersection which will include removing lanes on Lynn Street and Lee Highway and creating a bump-out on both the southeast and northeast corners of the intersection.

Less likely to see further investigation by the county transportation engineers is a suggestion to install traffic cameras to increase enforcement of drivers violating the cyclists' right-of-way.

However, participants raised questions about enforcement to the Arlington County Police. The police called for cyclists to travel at a safe, controlled speed, especially when traveling downhill, on the Custis Trail. Cyclists requested greater enforcement of drivers violating the right of way and driving while distracted to create a safer environment for bicycling.

While the intersection is unsafe for even a regular bicycle commuter, this intersection is even more unsafe for less experienced or less regular cyclists, for example those traveling through this "Gateway" between Georgetown and Arlington on Capital Bikeshare bikes.

Improvements could take many forms, including behavioral changes, engineering work, or better enforcement. But perhaps the best question is not how to make the intersection safer, but when we can make the intersection safer. After this evening's site visit, perhaps the best idea is to avoid crossing here in the meantime.

The North Lynn Street Esplanade and Lee Highway/Custis Trail Safety Improvements project is fully funded. This site study is also part of the larger, Rosslyn Circle project which includes all four intersections surrounding Gateway Park, for which there will be a public meeting October 5 at the Arlington Temple Methodist Church.

This crossing already had a walk/don't-walk pedestrian signal, which would inform cyclists about the status of the cross-traffic. Since right turns are prohibited on red, cars waiting on Oak Street will not create a conflict when the bike signal is green and the pedestrian signal is in the walk mode.

Cyclists need to watch for right-turning traffic from Lee Highway onto Oak. Although these cars are supposed to yield to bikes and pedestrian in the crosswalk, cyclists should double-check.

The above photo shows the bike signal still green while the pedestrian signal is flashing "don't walk" with 3 seconds left. Since bikes can cross much faster than pedestrians, this makes sense. There is a brief yellow bike signal that illuminates for 2-3 seconds before changing to red.

I did not observe bicycle behavior at this intersection with the new signal. The signal is green for much more of the time than it is red, probably 75% of the time. Most of the time cyclists will be able to proceed through this intersection without pause. It will be interesting to see how cyclists behave with this new signal: if they will treat it like a car would treat a traffic signal or more like an "Idaho stop."

It's great that Arlington continues to work to improve the cycling environment. Hopefully this new signal will increase safety and awareness.