Why do some tramways use kmph rather than mph?

[Boff]

I've only been on the London & Edinburgh trams, but I assume that at least a few others use kmph as well. What's the reasoning for this, as surely it would make sense to be in mph as they share roads (and thus theoretically speed limits) with cars?

 

[sktt25]

Can't speak for any other companies but at Edinburgh Trams they are made by CAF in Spain and in Spain the roads are all in kph.

 

[Boff]

Can't speak for any other companies but at Edinburgh Trams they are made by CAF in Spain and in Spain the roads are all in kph.

But surely it's not that difficult to switch the dials to mph - CAF make many British trains that have no problem using mph, despite railway track in Spain being in kmph.

 

[sktt25]

Possibly don't feel it's necessary. It probably costs to change it. As far as I'm aware the Edinburgh trams were purchased at the end of that models life cycle, so it is already more difficult to order new parts. This was perhaps considered.

In Edinburgh the speed limit is only shared on a very small amount of the route with regular traffic.

 

[The exile]

I've only been on the London & Edinburgh trams, but I assume that at least a few others use kmph as well. What's the reasoning for this, as surely it would make sense to be in mph as they share roads (and thus theoretically speed limits) with cars?

Might it not be the case that as new systems they have to by law?

 

[Volvictof]

Tyne and Wear metro (although not a tram) used Kph. I believe becuse the system was designed in the 1970s when the country was expecting to fully adopt the metric system, something which never happened.

 

[Boff]

Possibly don't feel it's necessary. It probably costs to change it. As far as I'm aware the Edinburgh trams were purchased at the end of that models life cycle, so it is already more difficult to order new parts. This was perhaps considered.

In Edinburgh the speed limit is only shared on a very small amount of the route with regular traffic.

That sounds like it could be the reason, although especially with the extension to Newhaven, quite a bit is sharing with traffic (or at least side-by-side with traffic, which should have the same speed limit anyways)

Might it not be the case that as new systems they have to by law?

I assume that that could be the case, but my question is why? - the UK has a very low chance of switching to metric now, so still having kmph in law is just adding complexity to an already complex measurement system.

 

[urbophile]

the UK has a very low chance of switching to metric now,

Is that the case? I know the Tories have been captured by the pro-Brexit*, pro-metric martyr faction. But the vast majority of the world (*very little of which is in the EU or ever was) uses the metric system; the UK shares an island with a state that counts distances and speed limits in kilometres; increasingly, local distances on signposts intended for walkers and cyclists are marked in metric. There are very many reasons why we should have bitten the bullet many years ago and converted everything. It is now very messy but there is no good reason why we shouldn't complete the process.

 

[simonw]

That sounds like it could be the reason, although especially with the extension to Newhaven, quite a bit is sharing with traffic (or at least side-by-side with traffic, which should have the same speed limit anyways)


I assume that that could be the case, but my question is why? - the UK has a very low chance of switching to metric now, so still having kmph in law is just adding complexity to an already complex measurement system.

The UK has already switched to the metric system, with only limited exceptions.

 

[Boff]

The UK has already switched to the metric system, with only limited exceptions.

Those exceptions include measuring height, long distances, weight of people, volumes of certain liquids and (crucially to this issue) speeds.

Is that the case? I know the Tories have been captured by the pro-Brexit*, pro-metric martyr faction. But the vast majority of the world (*very little of which is in the EU or ever was) uses the metric system; the UK shares an island with a state that counts distances and speed limits in kilometres; increasingly, local distances on signposts intended for walkers and cyclists are marked in metric. There are very many reasons why we should have bitten the bullet many years ago and converted everything. It is now very messy but there is no good reason why we shouldn't complete the process.

Hopefully we will switch - and I suppose an argument could be made that this is an attempt to encourage this, but having one system using kmph and one using mph on the exact same street strikes me as a really odd choice (and could potentially pose a safety risk). Also this means that buses usually overtake trams, as (at least in Edinburgh) trams run at up to 30kmph on streets, but busses can run a little bit faster at 20mph. (this really isn't an actual issue, just a bugbear of mine)

And if we were to switch to kmph, surely retrofitting a few signs and changing a few dials on trams is a tiny blip on the monumental task of changing every signal road sign in the entirety of the UK.

Also, on a separate note, what system does the Sheffield Supertram use, and if the Tyne and Wear metro uses kmph what happens when it shares track with mainline trains?

 

[simonw]

Those exceptions include measuring height, long distances, weight of people, volumes of certain liquids and (crucially to this issue) speeds.

A trip to a medical facility will reveal 1 and 3 are metric. Distances, only really roads and even then it's only certain signs , Certain liquids, again only in certain very limited circumstances. Speeds : not all speeds.

 

[JJmoogle]

Also, on a separate note, what system does the Sheffield Supertram use, and if the Tyne and Wear metro uses kmph what happens when it shares track with mainline trains?

Sheffield, like Manchester uses mph.

I think their use of mph is probably a historical artifact of being the first 'modern' street running light rail in the UK, everything that was segregated before then(DLR, tyne and wear) uses kmph, and everything built after them also, segregated or otherwise, including the modernised blackpool system.

 

[duffield]

Probably just as well that Sheffield uses imperial, given that part of it is tram/train, sharing some track with the -imperial apart from HS1 - national rail network. In Nottingham the tram network is metric but it only runs alongside the national rail tracks, it doesn't share them or connect to them.

 

[507 001]

KPH is indeed the standard for new tramways in the UK.

Metrolink and Sheffield are the only two using imperial speeds, although certainly in the case of Metrolink it’s only the speed limits done in MPH, everything else is metric.

In terms of the trams themselves, the only difference between one built for an imperial system and one built for a metric system would be the numbers on the speedo. M5000s actually have both MPH and KPH on their speedos, and any speed limiting faults are described in KPH.

 

[bramling]

Is that the case? I know the Tories have been captured by the pro-Brexit*, pro-metric martyr faction. But the vast majority of the world (*very little of which is in the EU or ever was) uses the metric system; the UK shares an island with a state that counts distances and speed limits in kilometres; increasingly, local distances on signposts intended for walkers and cyclists are marked in metric. There are very many reasons why we should have bitten the bullet many years ago and converted everything. It is now very messy but there is no good reason why we shouldn't complete the process.

What good reasons are there to change? Apart from the fact that people are used to miles, making the switch would be very costly. We seem to be at a point in this country where there’s barely money for essential stuff, so we certainly don’t need to be wasting money changing something that works perfectly well.

 

[507 001]

What good reasons are there to change? Apart from the fact that people are used to miles, making the switch would be very costly. We seem to be at a point in this country where there’s barely money for essential stuff, so we certainly don’t need to be wasting money changing something that works perfectly well.

Indeed, I’ve been driving for so long now that I’d find it very difficult to change to KPH as I think in MPH. Certainly in work it would be challenging as I can generally judge the speed I should be going based on my senses without looking at the speedo.

Obviously I would get used to it in time, and KPH speed limits would be the equivalent to the MPH speed limit, but to get a nice round number ending in a 0 or a 5 things would change slightly.

 

[47742]

What good reasons are there to change? Apart from the fact that people are used to miles, making the switch would be very costly. We seem to be at a point in this country where there’s barely money for essential stuff, so we certainly don’t need to be wasting money changing something that works perfectly well.

The reasons for radical and irreversible change are compelling and unarguable. We should exclusively use SI and metric units.

I was born in the early 1970s and was never taught how to deal with ludicrous mediaeval measurements which operate in multiples of 7, 12, or 13 and seven sixteenths. Let alone chains and fathoms. Get over your grief for and forget your backward-looking nonsense.

 

[blueberry11]

If the speed limit for the tram is the same as the car, when they see a normal 30 sign for cars, would they go 30 km/h (which would be 20 mph, 1.6 times slower than road traffic) or 50 km/h (which would be close to 30 mph)?

Also, other than the Manchester Metrolink, are there both km/h and mph speedometers?

 

[martin2345uk]

I now drive trains that have the speeds in kph and I still find myself "translating" in my head back to mph as the higher kph numbers don't "speak" to me in the same way that imperial speeds always have done...

 

[507 001]

If the speed limit for the tram is the same as the car, when they see a normal 30 sign for cars, would they go 30 km/h (which would be 20 mph, 1.6 times slower than road traffic) or 50 km/h (which would be close to 30 mph)?

No, because we don’t drive to the road speed limit signs, we drive to the tramway speed limit signs.

 

[The exile]

What good reasons are there to change? Apart from the fact that people are used to miles, making the switch would be very costly. We seem to be at a point in this country where there’s barely money for essential stuff, so we certainly don’t need to be wasting money changing something that works perfectly well.

That’s the main reason why the road network retained miles when weights and measures were changed. Tram networks are different as they employ people with specialist training (and as pointed out elsewhere have dedicated speed limit signs etc) so these considerations do not apply.

 

[Snow1964]

That’s the main reason why the road network retained miles when weights and measures were changed. Tram networks are different as they employ people with specialist training (and as pointed out elsewhere have dedicated speed limit signs etc) so these considerations do not apply.

History was we were becoming metric country, so new projects are metric. That is why distance markers on motorways are in km (and 100m interval poles), those from London always start at traditional zero milepost at Charing Cross (so motorway starts nearer 20-30)

Ireland changed to km for distance and speed (get double signs at border with Northern Ireland), so it can be done, but we kept mph. Even leads to stupidity like London buses where the Intelligent Speed Assist is in 10km/h increments so can't deal with 20mph limits.

But for trams safer to show km/h on diamond signs on shared sections so not to confuse motorists

 

[Mountain Man]

- the UK has a very low chance of switching to metric now,

The UK already uses metric. It's already switched.

The UK is a combined system.

You buy fuel for a car in metric, but measure distance of the car in imperial. The mapping of the country is divided into metric blocks, but the road signs in imperial. You're not allowed to drink alcoholic drinks whilst driving which are sold in imperial units, but you are a soft drink sold in a metric container.

 

[CarrotPie]

Even leads to stupidity like London buses where the Intelligent Speed Assist is in 10km/h increments so can't deal with 20mph limits.

Why is that a problem? 20mph=32km/h≈30km/h=3×10km/h

 

[AM9]

The UK already uses metric. It's already switched.

The UK is a combined system.

You buy fuel for a car in metric, but measure distance of the car in imperial. The mapping of the country is divided into metric blocks, but the road signs in imperial. You're not allowed to drink alcoholic drinks whilst driving which are sold in imperial units, but you are a soft drink sold in a metric container.

Fortunately the UK's metric phobic dinosaur generation is on the wane, and the population in general is now becoming largely metricated. That's not a snipe at older people, I'm in my mid seventies, throughout my imperial measure was taught with metric measure mention as a side issue, but when the UK started taking metrication seriously, which was around our conversion to decimal currency, I found it quite simple. Counting in decimal numbers has been the norm since the 150s and metric measurement since 1790. Metric denial in the UK is an aspect of the Not Invented Here syndome, which in many areas has held the nation back.

 

[Snow1964]

Why is that a problem? 20mph=32km/h≈30km/h=3×10km/h

Without going off topic, due to poor calibration some buses are limited to 30km/h or nearer 17-18mph in 20mph zones so cause others to do bad dangerous overtaking.

 

[AM9]

Without going off topic, due to poor calibration some buses are limited to 30km/h or nearer 17-18mph in 20mph zones so cause others to do bad dangerous overtaking.

They don't cause other drivers to break the law, - they might give them an excuse in their own minds where their attitude to safety is inadequate.

 

[Railsigns]

sharing some track with the -imperial apart from HS1 - national rail network.

The Cambrian line uses metric speeds (but imperial distances).

 

[Snow1964]

Fortunately the UK's metric phobic dinosaur generation is on the wane, and the population in general is now becoming largely metricated. That's not a snipe at older people, I'm in my mid seventies, throughout my imperial measure was taught with metric measure mention as a side issue, but when the UK started taking metrication seriously, which was around our conversion to decimal currency,

True, I was at junior school 1972-1976 and we had new metric rulers, and some new metric metre sticks and trundle wheels (but not enough so the old yard sticks were still stacked, but not supposed to be used.

No one has been taught old imperial system for half a century, have to pick bits of it up. I am 60 this year but wouldn't know what a dram weight or bushel or furlong actually feels like

 

[Greybeard33]

The reasons for radical and irreversible change are compelling and unarguable. We should exclusively use SI and metric units.

The SI unit of speed is m/s not km/h. The conversion factor is 3.6....