Comparison of 4'8 1/2" v 5'3" gauge

[lewisf]

AFAIK Standard Gauge was chosen for the Dublin Trams as 1. Cheaper ‘off the shelf’ trams from Alsthom and 2. Tighter curves possible than 5’3”. Nowt to do with the EU or funding conditions.

I would imagine that number 1 in your list is the sole reason the Luas is standard gauge. I also think that this is the reason tram speed limits in this country are metric, you can only buy trams with speedometers in km/h.

 

[Con]

I would imagine that number 1 in your list is the sole reason the Luas is standard gauge. I also think that this is the reason tram speed limits in this country are metric, you can only buy trams with speedometers in km/h.

There is a bizarre and possibly apocryphal story that when Luas was first proposed, former Taoiseach (PM) Garret Fitzgerald measured the proposed curve from St Stephens Green to Dawson Street and declared that trams couldn’t make the turn. Presumably he meant Irish Gauge rather than Standard, if indeed it happened at all.

Dublin is famously a city of rumours and pub talk, and I lost count of the taxi drivers and barbers in the early Noughties who swore to me that the Red and the Green lines couldn’t be connected, or the trams couldn’t be made interoperable, as they were constructed to different gauges. It was the loading gauge rather than the track gauge, a point lost on all the would be experts...

 

[randyrippley]

Tram systems were often built to a slightly odd gauge to allow standard gauge wagons to use the system riding on their flanges. Without looking it up I am not certain which way the adjustment was made i.e. 4' 8" or 4' 9".

why didn't they just use rails with the correct profile, instead of ones that were too shallow for a normal wheel to run on?

 

[DPWH]

A key advantage of wider track gauges is that where a steam engine's firebox is placed between the driving wheels, it can be bigger. The firebox can of course be carried on trailing wheels, but this reduces traction. Alternatively, the boiler can be pitched higher, but loading gauge. Or, the drivers can be made smaller but that increases piston speeds and wasn't suitable for high speeds. Despite this restriction, the most successful British types were of the 4-6-0, 2-8-0 and 2-6-0 wheel arrangements with the firebox placed between the drivers.

 

[edwin_m]

I would imagine that number 1 in your list is the sole reason the Luas is standard gauge. I also think that this is the reason tram speed limits in this country are metric, you can only buy trams with speedometers in km/h.

Metrolink trams have speedometers (and speed signage) in mph, I can't immediately recall whether Supertram does too but the other UK tram networks use km/h. Getting a speedometer in mph instead of km/h is about as difficult as arranging for the dashboard legends to be in English instead of French or German. However Ireland uses km/h for its roads so the choice there was a no-brainer.

There is a bizarre and possibly apocryphal story that when Luas was first proposed, former Taoiseach (PM) Garret Fitzgerald measured the proposed curve from St Stephens Green to Dawson Street and declared that trams couldn’t make the turn. Presumably he meant Irish Gauge rather than Standard, if indeed it happened at all.

Dublin is famously a city of rumours and pub talk, and I lost count of the taxi drivers and barbers in the early Noughties who swore to me that the Red and the Green lines couldn’t be connected, or the trams couldn’t be made interoperable, as they were constructed to different gauges. It was the loading gauge rather than the track gauge, a point lost on all the would be experts...

As you probably know but others may not, the Red and Green lines were originally designed as a single route linked by a curve at O'Connell Street where they now cross, so definitely compatible enough for through running. I spent a happy afternoon in 1996 reading through Garret Fitzgerald's depositions on the subject of the Luas route across the city centre, which seemed to be motivated mainly by a desire to maintain the unimpeded flow of private cars (to be fair neither the infrastructure nor the thinking had fully caught up with the city's rapid expansion while retaining a very rural and car-dominated hinterland). I don't recall that particular issue but there are some very tight turns in that area - which based on recent visits seem to be negotiated without any wheel squeal. After considering a tunnel route the city centre link was deleted leaving a gap between the two lines, which the recent cross-city connection has finally closed. The loading gauge issue is related to the tracks on the former railway section being spaced wider apart on the former railway section to Sandyford and on to Bride's Glen with the intention of allowing upgrade to a future metro with wider vehicles. The Bride's Glen extension (at least) also has provision to upgrade the power supply to 1500V. MetroLink is now proposed to take over this section as far as Sandyford, reinstating the tunnel idea to continue towards the airport, but as far as I'm aware the vehicles won't be any wider than Luas.

why didn't they just use rails with the correct profile, instead of ones that were too shallow for a normal wheel to run on?

The groove in a tramway rail is much smaller than would be needed for a railway wheel to run "properly". A flangeway large enough for railway wheels, as seen on quaysides and the Weymouth Harbour tracks, would be dangerous to cyclists and other road users.

 

[Pakenhamtrain]

In Great Britian we generally use 'standard gauge - 4' 8 1/2" As does much of Europe and N America
In Ireland, Russia and the Iberian peninsula, and historically in Australia, they use 5'3"

What do people think are the benefits and downsides of the 2 main gauges? Would a general application of 5'3" have allowed faster speeds?

What would have happened if Brunels broad gauge had prevailed in the UK?

And of course we all know standard gauge is set at that because its the distance between the neck and ankles of a damsel in distress

Australia for the most part uses 4'8 1/2. Broad guage was only in South Australia and Victoria.
Western Australia and Queensland and Tasmania went 3'6.

 

[furnessvale]

why didn't they just use rails with the correct profile, instead of ones that were too shallow for a normal wheel to run on?

A bicycle dropping in a tram groove is bad enough. Imagine dropping in one twice the depth.

 

[DavidGrain]

Birmingham trams and the tramway companies in the Black Country which connected with Birmingham all had 3ft 6in gauge. This was said to be because of the narrow streets and one route in the Balsall Heath area of Birmingham was know as the Chinese Railway because the streets were so narrow that the inbound and outbound trams had to take different routes.

You could always tell a Birmingham tram in a black and white photo because of the blanked off window at the bottom right of the cab. This was because of the narrowness of the tram meant that the glass had to be replaced with a bulging out metal plate to accommodate the turning of the brake handle and the driver's hand. This photo shows what is believed to be the first use of the Ultimate ticket machine on Birmingham Corporation as it was thought easier for women to handle rather than the bulky hand-held ticket rack,

 

[DelW]

why didn't they just use rails with the correct profile, instead of ones that were too shallow for a normal wheel to run on?

As well as the answers given already, it's possible that relatively lightly-laid tram track would have been damaged by goods wagon wheels bumping across points and crossings. In the US, where flat crossings are common, heavily used ones can be equipped with special rail sections which gradually lift wheels onto their flanges on approach, and lower them down again on departure, to avoid the impact loads from heavily-loaded wheels "banging the diamonds" as their phrase terms it.
https://www.railwaygazette.com/news...sing-diamonds-offer-improved-performance.html

INTRO: Trials at the AAR Transportation Technology Centre have found that flange-bearing crossings which reduce wheel impact loadings have the potential to cut track maintenance costs and operating delays, with no significant problems in terms of wheel wear.
....
In an FBF diamond, the wheel is supported on its flange while traversing the flangeway gaps. Typically the wheel load is transferred from tread to flange by raising the flangeway floor, enabling the wheel to be supported on its flange through the crossing.

 

[Ken H]

A bicycle dropping in a tram groove is bad enough. Imagine dropping in one twice the depth.

family myth said my grandma did that. managed to escape

There was also the studs in the road in London. A magnet caused them to be live as the tram went over them. but they sometimes stuck causing a few excited horses!

 

[AndrewE]

There was also the studs in the road in London. A magnet caused them to be live as the tram went over them. but they sometimes stuck causing a few excited horses!

In Torquay too... although I was told that they killed horses there.

 

[edwin_m]

family myth said my grandma did that. managed to escape

There was also the studs in the road in London. A magnet caused them to be live as the tram went over them. but they sometimes stuck causing a few excited horses!

Did London ever have stud contact? They had a system in the centre that avoided wires using two power rails in a conduit with a slot in the top.

 

[AndrewE]

Did London ever have stud contact? They had a system in the centre that avoided wires using two power rails in a conduit with a slot in the top.

Wikipedia (https://en.wikipedia.org/wiki/Stud_contact_system#United_Kingdom) says not, but does confirm that a horse got killed in Torquay.

 

[K.o.R]

Isn't the discrepancy in gauge for some of the tram lines because gauge is measured from the physical inside edge of the rail, even though in a grooved rail the actual "running rail edge" is the inside (outside?) of the groove, which would be a wider distance?

 

[edwin_m]

Isn't the discrepancy in gauge for some of the tram lines because gauge is measured from the physical inside edge of the rail, even though in a grooved rail the actual "running rail edge" is the inside (outside?) of the groove, which would be a wider distance?

No. The gauge is measured from the running face, which on a grooved rail is where the main part of the rail meets the groove.

 

[K.o.R]

No. The gauge is measured from the running face, which on a grooved rail is where the main part of the rail meets the groove.

That makes sense for tram lines that are slightly wider, meaning the standard gauge wheels are running on the very inside edge of the metal rather than in the groove (probably very bad for the rail if the wagons are heavy!), but doesn't make sense for the description of the Glasgow trams which had a smaller gauge. (Post #13)

 

[edwin_m]

That makes sense for tram lines that are slightly wider, meaning the standard gauge wheels are running on the very inside edge of the metal rather than in the groove (probably very bad for the rail if the wagons are heavy!), but doesn't make sense for the description of the Glasgow trams which had a smaller gauge. (Post #13)

The larger size and more triangular shape of railway flanges means that their bottom tips are further from the point of normal wheel-rail contact than tram flanges are. So railway flange tips will be closer together than those of a tramway with the same nominal track gauge.

Hence for both types of flange to fit in the same pair of grooves, the nominal track gauge of the tramway must be less than that of the railway. The wagons using the Glasgow tramway would have been running on their flange tips with the tread (that they would be running on when on railway) around an inch (at a guess) above the top of the rail. This is probably not ideal for either the wheel or the rail. Railway wheels are not designed for flange tip running, unlike many tram wheels which can run on flange tips through pointwork to reduce noise and vibration.

Incidentally tram-train wheels have a flange that is approximately of tramway dimensions but the inner part of the wheel is thicker so the distance between the backs of the wheels is the same as on a railway wheelset. The back-to-back dimension is important because the check rail at point engages with the back of one wheel to prevent the other wheel going the wrong way at a crossing. Hence check rails on tram-train routes have to be raised above the running rails to contact the thicker part of the wheel.