We are always looking for ways to minimize the traffic disruption that comes with maintenance work. I saw it first hand when our signals team had routine maintenance to do on those overhead signs along Interstate 90 – you know, the ones that display the speed limits for each lane that can change to a red X if there is a crash – we call them Active Traffic Management Signs (ATMS).
Normally to do maintenance on these signs, we close down the entire interstate for several hours so crews can go up in bucket trucks and work on all the signs along a stretch of highway. This time, they tried a new method to keep the highway open for those travelling along I-90 late Saturday night and early Sunday morning. Instead of a full closure, they used rolling slowdowns and closed a max of three lanes, leaving at least one lane open for traffic.
Now you may think that this would be the obvious choice, but this new method made some folks – especially the superintendent of the road crew – more than a little nervous. That's because instead of having a closed road where his crew was working, there was still traffic driving by at reduced but high speeds. The safety risk obviously goes up.
|Traffic control in place for Active Traffic Management Sign work on I-90.|
Creating a safe operation while still opening the road to drivers took a team effort. There were 11 rigs that were part of this operation plus two Washington State Patrol troopers. We had two bucket trucks, four dump trucks with attenuator cushions, two road warrior trucks stacked with traffic cones and barrels and three arrow board pick-ups. The first step was a team meeting at the WSDOT shop in South Seattle. There, the operation leader made sure that everyone understood the exact work locations, spacing of the trucks and how we'd coordinate movement from one maintenance site to the next. Questions were asked and clarified, and then the team suited up into their reflective gear and other personal protection equipment and lined up their rigs.
The operation moved like a well-oiled machine as we headed to eastbound I-90. We turned around at the roundabout on West Lake Sammamish and started moving westbound to our starting point. You can see a bit of the formation in the photo below. The first warning to drivers was a portable LED sign before the first maintenance zone letting them know about road work ahead. After that is when the trucks and teamwork came into play. It started with an attenuator dump truck blocking the HOV lane with a flashing arrow moving traffic to the right. Then another truck pushed traffic out of the left general purpose lane. Eventually a truck pushed traffic into the right general purpose lane. You can see the final two large trucks (a road warrior on the left of your screen an attenuator truck on the right) were situated as buffer several hundred feet before the bucket trucks, where two workers were harnessed in and were the flyers for the evening.
|Our crews use teamwork and a combination of vehicles and lighted signs to keep the work zone protected.|
Using this technique, trucks and crews played the role of very visible traffic control devices, gradually tapering lanes closed from a driver's left to right. We did this instead of dropping barrels so that as soon as crews finished work on one ATMS we could roll the operation forward to the next one – maintaining that safe zone for workers but keeping the lane reduction area condensed to keep traffic moving.
Oh, and in case you were wondering what we were doing out there...we were changing air filters. Just like the ones in your house and your car, they need to be changed regularly to keep the electronics in these signs operating correctly – and boy do they get dirty! With all the dust, wind and exhaust that blow through I-90, they turn from white to black in less than a year.
|What the ATM filters look like when they are new and after a year of use.|
Thank you to everyone who drove past us who slowed down and merged right. You helped create a safe work zone while we tried out a new way to do maintenance on these signs. Our crews will be out again starting at 11 p.m. on Saturday, March 19, until 5:00 a.m. on Sunday, March 20 – this time on a stretch of SR 520 both directions between mileposts 5 and 8 – using this rolling slowdown method again. Thank you in advance for using caution around them.