Express-lane switch stuck in slow motion
Automating I-5's express-lane gates and signs would allow the roadway to absorb up to 3,000 more vehicles a day.
Seattle Times transportation reporter
The express lanes of Interstate 5 go to waste every weekday for 50 minutes, the time it takes to reverse direction from southbound to northbound.
The task is carried out in the same cumbersome manner as when the Seattle freeway was built four decades ago. Two workers arrive in small trucks, hop out at a dozen entrances along the seven-mile stretch from Northgate to downtown, and flip the switches that move each set of gates.
By the time the lanes reopen going north, drivers in the general-purpose lanes approaching downtown are stuck in traffic, waiting their turn to get in.
What if the switching time were cut in half?
State Transportation Secretary Paula Hammond said she wants to automate the gates and signs so they can be switched more quickly, from the Department of Transportation traffic center in Shoreline.
That would allow the express lanes to absorb up to 3,000 more cars and trucks a day. A remote-control system could be tailored to baseball and football traffic, and it could be used to quickly reverse lanes when a crash blocks the mainline.
Automation is one way to add capacity to the freeway before 2012, when the nearby Alaskan Way Viaduct is supposed to be demolished to make way for a surface route or possible replacement highway.
"For the whole viaduct situation to work, I-5 has to work better," Hammond said.
DOT officials believe automation would cost less than $10 million. "I think there is a strong case here," said Morgan Balogh, a traffic engineer who is writing a cost-benefit study this year.
But agency leaders haven't decided yet whether to ask the Legislature for the money. The DOT has already pledged its recent gas-tax increases to other projects around the state. "Pretty much every dollar, top to bottom and side to side, is spoken for," said chief operating officer David Dye.
This week, signal technician Allen Mushatt parked his truck in the northbound left shoulder, just beyond Northgate. He phoned the control center in Shoreline at precisely 11 a.m., the first step in a 52-point checklist. He unlocked a steel cabinet and flipped the switches to change southbound signs and gates to "closed."
Then he unfurled and anchored a net, to catch any cars that might hurtle through the breakable gates.
Mathew Matson flipped the switches at the Northeast 103rd Street, Lake City Way Northeast and Northeast 42nd Street onramps. He walked up the street to confirm that nearby sign messages were accurate.
The antiquated control box at Northeast Ravenna Boulevard had red tape over one switch because, if it were tripped, drivers would see conflicting messages. At Ninth Avenue, the green entry sign malfunctioned, so Matson set the message to blank. The final switch box, in south downtown, had indicator lights almost too faint to see.
If a step is performed out of sequence, drivers might accidentally speed the wrong way into the express lanes, or make sudden lane changes in the general lanes.
As noon drew near, a clump of traffic extended more than a mile, from the left-side Seneca Street exit to the West Seattle Bridge interchange.
The huge, pivoting guardrail blocking the entrance swung open. Within five seconds, the left lane to enter the newly northbound express lanes filled — proof of the pent-up demand.
Mike Lindblom: 206-515-5631
Copyright © 2008 The Seattle Times Company
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