Our correspondent says there will be serious question about how a major tunnel on one of Japan's most important traffic arteries could have failed so catastrophically, with the private company that runs the highway saying the tunnel had undergone a major inspection just two months ago and had been given a clean bill of health.

BBC: Japan Sasago tunnel: Collapse traps cars

The upgrades at Port Miami - including a tunnel under the bay designed to link a highway with the port - are being funded by taxpayers as well as private investors.

BBC: Obama promotes infrastructure plan at Miami port

Craning our necks to see the front of our train nose out of a tunnel as the back of it enters, down below we spot the Trans-Canada Highway, laid on top of the original Big Hill track bed.

BBC: The wonders of Canada by rail