Traffic Q&A: Why are the lane widths different on the new Pac Ave bridge?

The new Pacific Avenue bridge over Interstate 5 in Tacoma will have different lane widths that the previous bridge.
The new Pacific Avenue bridge over Interstate 5 in Tacoma will have different lane widths that the previous bridge. Washington Department of Transportation

Q: What’s the deal with Pacific Avenue bridge traffic lanes being different widths? — Peter C., Minneapolis

A: Two things to address here, dear readers.

First, why take a traffic question all the way from the Land of 10,000 Lakes?

Second, what is this Peter C. talking about?

First things first.

Peter C. is erstwhile News Tribune columnist Peter Callaghan, who took his acerbic wit and encyclopedic knowledge of Tacoma back to the flatlands of Minnesota in 2014. Despite his new address, he retains a fascination with T-town, where he grew up and made his journalistic bones.

As to his question, we here at Traffic Q&A headquarters believe he is referring to the illustration that ran with a story we penned last week about the imminent reopening of the Pacific Avenue bridge over Interstate 5 in Tacoma.

That illustration compared the lane alignment of the old bridge — four 12 1/2-foot lanes with two 6-foot sidewalks on each side — to the alignment of the new bridge, which will have a 14-foot-wide multiuse sidewalk on one side, a 6-foot-wide sidewalk on the other and one 12-foot-wide lane, two 11-foot-wide lanes and one 14-foot-wide lane in between.

We put Peter’s question to Claudia Bingham Baker, queen of communications for the state Department of Transportation’s Olympic Region.

Said Bingham Baker:

“Yes, there is a method to our madness. Six feet is the standard width of a sidewalk, ergo the 6-foot sidewalk on one side. We wanted to provide a multiuse path for bicyclists and pedestrians, so we widened the other sidewalk to 14 feet to make room for both.”

OK. So far, so good. But what about those whacky traffic lane widths?

Said she:

“It’s not uncommon for us to build inside lanes on overpasses 11 feet wide and outside lanes 12 feet wide. The 11-foot-wide lanes provide adequate space for cars and trucks; however, we assume trucks will travel mainly in the outside lane and the 12-foot-wide lane gives them just a little more room.”

We’ll buy that. But what about that 14-foot-wide monstrosity?

Again, Bingham Baker:

“The 14-foot-wide lane is the outside lane in the uphill direction. The grade on the overpass is relatively steep, and we know that trucks will tend to slow down going uphill. The extra 2 feet (from 12 feet to 14 feet) provides even more of a buffer to accommodate slower-moving, larger vehicles.”

So there you have it.

The new overpass, by the way, is to open Aug. 19.

High impact closure

Here’s an early heads-up that southbound state Route 167 will close between Ellingson Road and Eigth Street East near Algona the weekend of Aug. 19-22.

That’s right: Close.

Crews will be installing a fish-friendly culvert as part of an improvement project there.

The Transportation Department encourages people to detour around the closure via state Route 18 or I-5.

Red light follow-up

The careful reader might recall that in last week’s column we whined that the cities of Tacoma and Lakewood were not posting data about their “automated traffic safety cameras,” read red-light and speed-enforcement cameras, on their websites as required by law.

Tacoma has since rectified that error. You can find its numbers here.

Still waiting for Lakewood.

Adam Lynn: 253-597-8644, @TNTAdam