None of these technologies is experimental: they are proven, low-cost solutions, and most of them take advantage of the fact that we are already digging 150 km of tunnels and 150 stations. Here are the five pieces, and the detailed page for each.
No gasoline engines, so no exhaust: keeping the air clean is simpler here than in a road tunnel.
Textured concrete and absorbing panels: a library ambiance rather than a cathedral.
Gobo projectors and birdsong to dissolve the feeling of being shut in.
Rock at 10 °C heats the stations in winter and cools them in summer, almost for free.
The wall paint glows during a total outage — with no electricity and no maintenance.
Why it matters
The biggest objection raised against a bike tunnel is not that it is hard to dig — it is that people picture a dark, noisy, stifling, energy-hungry pipe. Each of these five technologies answers one of those fears directly, and they reinforce one another: clean air, controlled sound and a living ambiance make the trip pleasant; geothermal energy makes it lean; phosphorescence makes it safe even when everything else fails.
Two of them build on an advantage unique to going underground: because we are already boring through rock, geothermal energy comes at marginal cost; and because there is no gasoline vehicle, ventilation has almost nothing to clear out. The tunnel thus becomes not only a transport network, but a lean energy infrastructure — an argument for energy independence resting on Québec's hydroelectricity and the heat of its ground.
A concrete tube, transformed.
Clean air with no engine, a library-grade quiet, a moving sky and foliage, stations tempered by the ground, and emergency lighting that depends on nothing. Five simple technologies that make the difference between “a tunnel” and a place you want to ride through, 365 days a year.
The figures shown (CO&sub2; levels, echo time, energy savings) are preliminary orders of magnitude. Each page details its assumptions; a specialized engineering study would set the final numbers.
Main sources. The machine and the reference project — the Music City Loop in Nashville: The Boring Company (official page, Prufrock machine, NFPA-130) and Tennessee government (100 % private project, 1st phase of 10 miles). An honest status update on the timeline: Wikipedia (Music City Loop) — as of February 2026, tunneling had not started and permits were not finalized —, Nashville Banner and WSMV (first turn of the Prufrock machine, tunneling targeted « in January at the earliest »).