[ifwinterco]

It would be way more annoying for LHT countries to change to RHT than to switch from US units to metric, have to change literally every road sign, street light, road markings etc in the entire country.

Plus everyone would then be driving cars with the steering wheel on the wrong side for decades until the whole fleet got eventually replaced.

Countries have done it before, but I think there's a reason not many countries have done it since the mid 20th century when roads and cars were a lot simpler and there were fewer of them.

Switching to metric could be done gradually - replacing existing signs with metric ones only when they wear out, building new systems in metric while still using US units for the old ones.

There's no way to gradually switch from LHT to RHT, you have to somehow do a switchover in a day

[SideburnsOfDoom]

> It would be way more annoying for LHD countries to change to RHD

As a complete aside, 1 country has done this: Sweden on 3 September 1967 and "It was by far the largest logistical event in Sweden's history"

https://en.wikipedia.org/wiki/Dagen_H

[cwmma]

Iceland did it a year later, https://en.wikipedia.org/wiki/H-dagurinn, but since there was less then 200k people living there it was a much less dramatic change

[ifwinterco]

IIRC a lot more countries did it but mostly a lot earlier (pre ww2).

Back then it would have been comparatively easy, cars were slow and there were barely any street signs etc anyway

[qingcharles]

Falkland Islands did it for a brief second, though not by choice.

[NordStreamYacht]

> There's no way to gradually switch from LHT to RHT, you have to somehow do a switchover in a day

You could do it in phases. Have the trucks switch over on Monday, buses on Tuesday ...

[GJim]

And we would want to do that because......

[NordStreamYacht]

Because it would be the cause of much mirth?

[einherjae]

We can take jokes…

[GJim]

Jim Davidson has displayed greater wit and comedy.

[NordStreamYacht]

Who is Jim Davidson when he's at home?

[ghaff]

And the US and various other countries (like the UK) effectively use hybrid systems for units for many purposes. Science and engineering in the US are heavily metric.

[ksec]

I used to think about whether we can get more countries switching back to LHT, but with Autonomous Vehicles that will no longer be much of an issue in 10 - 20 years time.

[SideburnsOfDoom]

I am told that Left Hand Drive is marginally safer (all other things being equal) because of the preponderance of right-handed people. Driving on the left of the road places the right-handed driver's dominant hand on the wheel and dominant eye towards the centre of the road and oncoming traffic.

However this is not an argument in favour of 20th century style, non-autonomous individual vehicles as the main transit solution. There are safer and better ways. Autonomous Vehicles will hopefully play a role in that.

[KineticLensman]

You'd also have things like bus doors now being on the wrong side (traffic-side), road curvature being wrong (e.g. motorway junctions and entry/exit ramps), let alone car mirrors and driver positioning.