Why do some tramways use kmph rather than mph?

[LNW-GW Joint]

London Underground stuck to MPH when the S stock was introduced for the above reasons.

Although the LU itself is measured (distances) in km.
NR uses imperial for its physical routes (distances, speeds etc), but metric for the components of those routes (track, OHLE etc).
The ECML is measured in metric (since electrification).
New lines starting with the Heathrow branch* (maybe earlier) are in metric.

* Actually measured from the zero at Paddington, the changeover being at 12m27c = 19846m.

 

[AM9]

Personally I think the country should have gone fully metric decades ago. But you appear not to have read what I wrote. My opening sentence states that all imperial units are defined by metric measures and yet you repeat a version of these words as if I had said something else.

I did read you post and was actually agreeing with you here with some added detail. We are now some 50+ years since all schools were obliged to teach metric measurement, so the diminishing number of people who can claim that they were taught imperial measurement largely accommodate metric if it suits them. There was also a backlash in the '70s trying to keep imperial measurement going in perpetuity, which of course it wasn't. However Johnson decided to re-light this daft idea a couple of years ago because metric - Europe interference, a truly Brexiteer fantasy. @The exile seems to think that 'old habits' should be indulged forever, even though jam and similar commodities don't need to be a particular size, and have been changed by manufacturers when so called 'shrinkflation' is the order. Milk has been sold in polythene or waxed paper disposable containers now for 40 years, so the death of independant dairies would not be likely. In fact, many milk products are sold in 1/2, 1 & 2L quantities.

 

[Flying Snail]

Non metric units are tolerated because
A) you cannot legislate inside people’s heads, so “old habits” will die hard. (There are still surviving elements of pre-metric measures to be found on the continent decades/ centuries after metrication - just look at the contents of a jar of jam!)
B) because of the cost / safety element of conversion. Changing milk bottles to metric in the 1970s would have killed off many independent dairies - likewise beer glasses etc (note that spirits did go metric). Changing road speed limits is a conversion on a scale almost comparable to changing to driving on the right in the sense that it can’t be done in drive and drabs, so no one has yet dared.

Ireland changed all speed signs and limits from on 20 Jan 2005 so yes it has been dared and done.

You could argue that it is a good deal of work and expense for little tangible benefit though.

 

[birchesgreen]

It wouldn't really be that hard to switch road signs to kilometres, its just a number you have to reach anyway. If the sign says 30 or 40 you just have to reach that in your car and know you are there when you see the speedo.

Though few people obey speed limits in any case...

 

[Railsigns]

Ireland changed all speed signs and limits from on 20 Jan 2005 so yes it has been dared and done.

You could argue that it is a good deal of work and expense for little tangible benefit though.

It would stop the Welsh moaning about all the "20" signs on their roads.

 

[Cloud Strife]

Ireland changed all speed signs and limits from on 20 Jan 2005 so yes it has been dared and done.

Yes, it's not impossible. The problem is more the unnecessary cost.

 

[185]

A moment of hilarity some years ago regarding this. One tram company (which uses MPH) poached an NR manager who I know well, for a quite senior position. Three weeks into his new job, he pulled me up in a discussion about a problem foot crossing, adamant "oh no, those signs are KPH"... this argument lasted over an hour.

He since returned to another top position back at NR but, childish as I am, still take great delight in reminding him.