The new 520 bridge: a case for 8 lanes

The Highway 520 bridge project has been narrowed politically to six lanes. Six is all Seattle will accept. Maybe that is so, but a good case can still be made for eight. This is a decision that will be set in concrete, and our children will have to live with it.

The region is living now with a bridge that opened in 1963. Back then, it opened with almost no traffic. Two lanes would have handled all the traffic there was.

But the philosophy then was to build for the future. The original Mercer Island floating bridge was built in 1940 with four lanes, for the future. The Aurora Bridge was also built for the future. The old postcards show both of these spans almost empty.

The modern idea is to build bridges with general-purpose lanes that are full on opening day and jammed thereafter. The state's six-lane proposal for 520 adds no general-purpose lanes. It does, however, add two 12-foot bus-and-carpool lanes, which are absolutely needed, and a 12-foot pedestrian and bicycle lane, which is nice to have. It also has 40 feet of shoulder width, compared with 6 feet on the bridge now, which adds some safety and a place for disabled vehicles to pull over.

In total, the proposed new bridge is 131 feet wide — more than double the 60-foot width of the current bridge and with no more lanes of the kind most users want.

The political intention is clear: to declare to the world that all the growth in traffic on the corridor in the next 100 years will be from pedestrians, bicycles, carpools, vans, buses or other transit, and none from trucks or cars. This is what some people in politics say they want, but it is not what anyone should expect. Its vision is utopian.

Make room here for cynicism. More people are praising this vision than actually believe it. When the I-90 project was negotiated, at one point the Eastsiders wanted eight general-purpose lanes. Seattle insisted on six. The finished bridge had six but was wide enough to be restriped for eight — and now the state has proposed to restripe it.

The same appears possible on the 520. The planned six-lane design could be made into eight lanes with a few cans of paint — and if it is built, it likely will be. It would be more honest, though, to plan for eight lanes from the start.

The engineers' objection has been that eight lanes would bring too much traffic to Interstate 5. The solution to that, as outlined by Eastside road planner James MacIsaac, is to peel off two lanes at Montlake, probably to land them at Husky Stadium, so that only six lanes (two of them for buses and carpools) join I-5.

In other words, it can and should be done. Six lanes with restrictions to the current four lanes of general usage is too small for the region.