Argument: Tunnels last longer and are cheaper to maintain
- Debate: Seattle deep-bore tunnel - pro argument.
John Reilly, a leader in the International Tunneling Association: "Politics is often focused on initial capital cost, but we must look to total life-cycle cost. Tunnels cost more to build but less to maintain. They last a lot longer than elevated structures or surface streets."
"Delaying the Green Tunnel is Seattle’s Biggest Risk." lightandair. July 13th, 2010: "Tunnels are not a risky investment. A new tunnel has a useful life of about 150 years. Even the relative weak 19th century tunnels last that long. Surface improvements such as roads and viaducts typically last 50 years at most. Surface improvements to old highways like I-5 are likely to have an even shorter useful life think twenty years. So even when tunnels cost more initially they are often more cost-effective long-term. In the Northwest we seem to be constitutionally averse to large investments that save money in the long run – that’s why we are still building boats across Lake Washington."