[breadAndWater]

Driving doesn't fit into such a world view. Driving through a long tunnel never lasts up to 30 minutes, and tunnel lengths are never such that if your car got stranded, walking out on foot to reach the surface would challenge people with small children.

Subways are categorically a different animal. Of lesser endurance than light rail networks, the excess of amount of time spent within them is due to unintended delays and speed limits that draw out travel times. Spending more than 45 minutes on a subway trip is often viewed as unhappily inconvenient and/or an error.

[dragonwriter]

> Driving through a long tunnel never lasts up to 30 minutes, and tunnel lengths are never such that if your car got stranded, walking out on foot to reach the surface would challenge people with small children.

Aside from unusual traffic delays, you are probably right about the 30 minutes thing (the longest road tunnel is just over 15 miles long), but it also has no emergency exits other than the ends, and the maximum 7.6 mile trek to an exit with both ends clear (and, a fortiori, the longer possible exit journey if not starting at the middle but a near end exit is not possible) are likely to challenge people with small children. LLP