Tacoma Park and Ride Update – Traffic
Oct 24th, 2009 by reid
Last Updated: Nov. 17, 2009
This is part one of a three-part update series on the Tacoma Park and Ride Station for the Portland-Milwaukie Light Rail line.
Remember, there’s a Light Rail meeting this coming Monday, October 26th at Ardenwald School in Milwaukie. It’s on the calendar to the upper right as well. The Oregon Department of Transportation (ODOT), who, among other things, manages McLoughlin Blvd. (OR State Route 99E) and Oregon State Highway 224, will be taking questions about traffic going to and coming from the Tacoma Park and Ride.
This first part deals with DKS Associates’ traffic analysis of trips going to-and-from the Park-and-Ride.
The full set of traffic analysis slides are available on the Tri-Met project site at http://trimet.org/pm Look in “Library” and “Documents from Past Community Meetings” for the DKS Associates Johnson Creek Traffic analysis, which covers an area to McLoughlin and to SE 17th & Tacoma. Slide #12 is the one you really want to look at.
30% of the Park and Ride users will come in on Johnson Creek, from the East.
Only 25% of the Tacoma Park and Ride users will come up McLoughlin from South of the McLoughlin/224 interchange. Many of those users will come from North of the Oak Grove Park Avenue Park-and-Ride station. 25% of all Tacoma Station users will come from the East on 224, then link onto SE McLoughlin to go the last mile to the station.
About 8% of vehicle trips going to the Park and Ride will be SMILE residents going down Tacoma. 12% of vehicle trips to the Park and Ride will come from West of Sellwood Bridge.
So, even if the station fills up to 1000 users a day, only 120 of those users are coming over the Sellwood Bridge. And those folks are going in lanes against the direction of rush-hour traffic.
If a Lake Oswego-to-South Waterfront Streetcar goes in, we might see fewer of those folks as well.
One of the items the community had questioned was how long the cars driving into the site (or leaving the site) via the North-side ramp into the Park and Ride from the Tacoma overpass. It turns out that, including lights flashing, crossing arm dropping, train passing, arms going up and access being clear again is a 50 second cycle. It will happen once every 7 minutes. That means for every 6 minutes and 10 seconds out of 7 minutes, the pathway will be clear. That’s 88% of the time where the access to the station will be clear. Unlike freight trains, Light rail trains are exactly two cars long always. It makes for a pretty short crossing time.
Regardless of whether the Park and Ride gets built, the traffic analysis showed that Johnson Creek traffic volume will steadily increase through 2015. That’s because it’s the only real East-West traffic corridor North of 224, but South of Holgate, the next totally straight shot into a downtown connector, and South of Powell, the next high-volume straight shot in from the East. The Ardenwald neighborhood is actively engaged with Tri-Met and the cities of Portland and Milwaukie discussing the suggested mitigation options for traffic management.
Although the DKS traffic analysis determined that the existing Southbound onramp was adequate, various community members in Portland and in Milwaukie have suggested adding a Southbound access path to the current Southbound exit path on the Northwest corner of the Tacoma overpass, acting as a NW corner cloverleaf on the exit.
ODOT says they don’t have the funding or resources to be able to do that, but they are currently examining the possibility of having the right-hand Southbound lane of McLoughlin act as a slow-down lane and “drop lane” for the two Southbound exits that leave just North of and just South of the Tacoma overpass. Southbound traffic would all exit this lane by the SW corner offramp onto Tacoma, leaving it empty just South of Tacoma. They’re also looking into the possibility of removing the stop sign at the base of the Southbound onramp and adding some space for a better “add-on” acceleration lane after Southbound users enter McLoughlin. Users in this lane wouldn’t have to merge with McLoughlin traffic, they would just be added to the McLoughlin traffic as a new lane. Since the lane is emptied by traffic leaving McLoughlin just before the new traffic joins McLoughlin, there would be no slowdowns as people attempt to merge. This would have the effect of keeping the onramp drained of users and ready to accept new users turning left from Tacoma. With enhanced signage and marking at the base of the onramp to keep pedestrians safe, this could be a really positive solution for keeping the Southbound traffic flowing away from the Tacoma Park and Ride. Additionally, it wouldn’t change the existing interchange configuration, so maps, GPS and navigation aids would still be accurate after the changes, but traffic flow would be enhanced. It’ll be interesting to see where ODOT’s discussions go on this subject. You can contact ODOT’s community affairs coordinator, Elizabeth Craig, by sending her a note at:
Elizabeth (put a dot here) Craig (put an @ here) odot (dot) state (dot) or (dot) us
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