The reason for traffic counting tubes west of Bremerton

The in basket: Ed Runquist asks “Why are the vehicle counters that stretch across the highway some times a single cable and sometimes two cables?  About a week ago when traveling from auto center towards Gorst, there were actually four cables near the last underpass.”

I, too, saw cables on the downgrade where traffic coming out of Bremerton meets the remaining lane of southbound traffic on Highway 3, though I thought there were only three. 

I can’t be sure Ed and I are talking about the same spot in that interchange. There were cables across the through lanes and one on the off-ramp to go into Bremerton, too. 

I wondered if the state was comparing traffic counts coming out of Bremerton and on Highway 3 coming south, a notorious backup scene on weekday afternoons. They’ve said no to suggestions about revising the alignment there in the past, but I wondered if they were rethinking.

The out basket: No, says Steve Bennett, traffic operations engineer for the Olympic Region of state highways. The tubes are counting traffic in preparation for reinforcement safety work on the rocky cliffs near Windy Point between there and Gorst the summer of 2011. The work, to include rock bolting and installment of mesh screens, will require lane closures. 

As for why there are different numbers of tubes stretched across the traffic lanes in these counts, Steve says, “We use two tubes (near one another) on highways, typically, for two reasons.  

“The first is when we have two lanes going the same direction, as we do on (Highway) 3, and we want individual lane counts.  

“The first tube stretches across both lanes while the second stretches across just the near lane.  From this, the tube that crosses both lanes gives us the total count for the highway and the other tube gives us the count for the near lane, thus enabling us to know the counts for each lane. 

“It is done this way to minimize the amount of time personnel have to work in the middle of the highway.

 “The second reason there may be two tubes on a roadway is redundancy,” he said.  “On high speed/high volume roadways, tubes tend to become damaged and/or non-working at a higher rate than on lower speed/lower volume roads. 

“Doubling up increases the odds that we will get the data we need without having to come back later and/or potentially delaying whatever project we may be needing the data for.”

He also said there are only two tubes on that downgrade where  Highway 304 joins Highway 3. That certainly was true on Feb. 23 when I went back and looked. Either I was mistaken in what I thought I saw earlier or it was changed. Since then, both tunes for southbound Highway 304 have been moved back closer to Bremerton.

When I asked if multiple cables also can record vehicle speeds and the number of axles, Steve said yes.

And when I asked why there are two tubes on the downgrade, but only one on the corresponding off-ramp on the other side of the highway, for traffic heading into Bremerton, it turns out there is one more reason for variety in the number of tubes deployed. 

After putting out the tubes on the on-ramp and the mainline in both directions, Steve said, they only had one left.