An analysis by the city council’s central staff concludes that light rail could conceivably fit within the 115-foot-wide footprint of the state’s preferred option for replacing the 520 bridge, eliminating the need to build a wider bridge now. Potential changes to the plan include narrowing bike lanes and shoulders from the state’s current assumptions—something that’s already been done on the I-90 bridge across Lake Washington to accommodate light rail there.
The central staff memo also confirms that, as we reported yesterday, expanding the new 520 bridge across Lake Washington to 125 feet, as Mayor Mike McGinn has proposed doing to accommodate light rail, could have the ironic unintended consequence of “mak[ing] it easier to [convert] the roadway to eight-vehicular traffic lanes in the future … through restriping and other minimal retrofit activities. … [W]ithout a regional agreement for light rail configuration on the SR 520 corridor, a wider roadway would allow for relatively easy conversion to additional vehicle lanes.”
Shrinking the footprint of the bridge back down to six lanes (while still accommodating light rail) would eliminate the possibility that the state could restripe the bridge for eight lanes. But it would also take some of the wind out of McGinn’s argument that this is the city’s only opportunity to fight light rail on the bridge—that, as he put it in a press briefing Tuesday, “We only have one chance to get this right.”
Central staff also looked at the state department of transportation (WSDOT)’s claim that it’s meeting the letter of a 2007 law requiring that the bridge “be designed to accommodate light rail in the future”—concluding, essentially, that it’s impossible to say. “The notion of ‘accommodating’ light rail in the future as currently prescribed by state statute is ambiguous and inherently subjective. The degree to which accommodations are made through the design and construction of the SR 520 project deeply depend on certain assumptions regarding light rail for the corridor that have not yet been made by the City or the region.”
Finally, the analysis found that although the state wouldn’t have to do additional environmental studies to widen the gap between eastbound and westbound 520 lanes over Foster Island to accommodate rail, adding pontoons would require a new environmental impact statement, and cost the state between $150 and $200 million.
The city council will take public comment on consultant Nelson/Nygaard’s report on the various 520 options tonight in council chambers at 5:30.
