Smart motorways are (not) more dangerous

[Boustrophedon]

The US highways that do this do it by having a string of concrete barriers that a special equipped vehicle can move from one side of the shared lanes to the other in the middle of the day/night.

The other method is to have HOV/express lanes that are separated from the main lanes in both sides, and which are only open to toll-paying/vehicles with 2 or more passengers, and which can be closed for each direction as appropriate.

These existed on the M25 for a while but they sold off the barrier moving vehicle. Some were installed installed on the M20. https://www.highwaysindustry.com/moveab ... n-the-m20/

[bob sterman]

In the UK you also have a lot of major trunk A-roads with the same 70mph speed limit as motorways, no hard shoulder, bicycles and milk floats allowed (IIRC - maybe only sometimes?), and vehicles joining from stop signs coming out of little side at 90 degrees.

True. But on many A-road sections there is a grassy "soft shoulder" that you stand a good chance of being able to get most of your car onto. Whereas on new smart motorways with all lane running there is a crash barrier to prevent vehicles leaving the carriageway.

No idea whether lack of crash barriers and an accessible "soft shoulder" (perhaps with trees to crash into) is on balance a safer alternative - but it does give you the option of leaving the carriageway.

[Grumble]

Driving down a smart motorway this morning there was someone parked up on the grass verge at the side. Luckily there was a verge at that point.