I’m honestly really skeptical of the cost effectiveness of pedestrian tunnels as a form of transportation. Asking Claude for estimates on tunnel construction costs gets me the following:
A 1-mile pedestrian tunnel would likely cost $15M-$30M for basic construction ($3,000-$6,000 per foot based on utility tunnel costs), plus 30% for ventilation, lighting, and safety systems ($4.5M-$9M), and ongoing maintenance of ~$500K/year.
To put this in perspective: Converting Portland’s 400 miles of bike lanes to tunnels would cost $7.8B-$15.6B upfront (1.1-2.3× Portland’s entire annual budget) plus $200M/year in maintenance. For that same $15.6B, you could:
Build ~780 miles of protected surface bike lanes ($2M/mile)
Fund Portland’s bike infrastructure maintenance for 31 years
Give every Portland resident an e-bike and still have $14B left over
Even for a modest 5-mile grid serving 10,000 daily users (optimistic for suburbs), that’s $10K-$20K per user in construction costs alone.
Alternative: A comprehensive street-level mural program might cost $100K-$200K per mile, achieving similar visual variety at ~1% of the tunnel cost.
I’m honestly really skeptical of the cost effectiveness of pedestrian tunnels as a form of transportation. Asking Claude for estimates on tunnel construction costs gets me the following:
A 1-mile pedestrian tunnel would likely cost $15M-$30M for basic construction ($3,000-$6,000 per foot based on utility tunnel costs), plus 30% for ventilation, lighting, and safety systems ($4.5M-$9M), and ongoing maintenance of ~$500K/year.
To put this in perspective: Converting Portland’s 400 miles of bike lanes to tunnels would cost $7.8B-$15.6B upfront (1.1-2.3× Portland’s entire annual budget) plus $200M/year in maintenance. For that same $15.6B, you could:
Build ~780 miles of protected surface bike lanes ($2M/mile)
Fund Portland’s bike infrastructure maintenance for 31 years
Give every Portland resident an e-bike and still have $14B left over
Even for a modest 5-mile grid serving 10,000 daily users (optimistic for suburbs), that’s $10K-$20K per user in construction costs alone.
Alternative: A comprehensive street-level mural program might cost $100K-$200K per mile, achieving similar visual variety at ~1% of the tunnel cost.