How transportation can transform a city – Seattle’s double decker tunnel

(Washington State Department of Transportation)
The new Highway 99 tunnel stretches from the industrial tangle south of downtown, near one of the West Coast’s biggest seaports and two major stadiums, north to where the late Microsoft co-founder and philanthropist Paul Allen over the past decade transformed a sleepy neighborhood into a vibrant commercial and residential corridor, now anchored by Amazon. ‘Building a 21st-century city’
Built during the freeway construction frenzy of the 1950s as one of two north-south corridors through Seattle, the viaduct is part of State Route 99, a patchwork of surface streets, freeway segments and the 3,000-foot Battery Street tunnel. The viaduct replacement has frequently invited comparisons to Boston’s infamous Big Dig, the rerouting of that city’s elevated downtown highway into an underground tunnel that was plagued by design flaws, enormous cost overruns and delays.

Source: www.washingtonpost.com