The question of equipment loading gauge has come up in the D&RG and Narrow Gauge in Ohio threads. I’ve had a question about this for some time and now seems as good time to trot it out, namely, what is the limit of loading gauge for a given track gauge? About all I can figure is that it’s all built around the center of gravity and the lower that is, the better. Assuming a car load of uniform density and a car floor height of-what is the US standard, 48"?-whereabouts do we start maxing out car sizes (assuming that clearances with lineside structures would not be an issue)?
In light of observations made on the other two threads, if we had somehow settled on a 3’ gauge in North America, I’d guess that we’d would still have COFC freight but not doublestacks-right or wrong? PRB coal would be moving in longer trains of smaller cars-but would they be very much smaller? Conversely, if the Erie had inspired a broad gauge (6’) revolution here, would the equipment we use today be that much bigger? Triple stack well cars? Side by side containers? 160 ton coal cars?
I’ve always wondered “what if” but I don’t know the science behind the “balancing act” as it were. Any ideas, anyone?
The loading gauge is a measure of how wide/tall a load can be, and is much more a function of bridge, tunnel and lineside structure clearance than it is of track gauge or weight of lading.
The US and the UK have a common track gauge, 1435mm. The US loading gauge is so much bigger that normal-size rolling stock would put British lineside structures at considerable risk, not to mention getting stuck like corks in some of the tighter through truss bridges. OTOH, the South African Railway is 1067mm gauge, but has a loading gauge larger than the railroads in the UK.
Of course, there is one exception in the UK. Since Brunel built the Great Western with seven foot 1/2 inch gauge (what’s with this 1/2 inch thing the Brits seem to have stuck into all of their early track dimensions???) former GW routes have a gigantic horizontal loading gauge by UK standards. (The former Erie has the same in the US.)
There is also very little correlation between loading gauge and weight of lading. Pieces of aircraft can be nudging the Plate E loading gauge, but weigh comparatively little. Those proposed nuclear material carrier casks probably won’t even overhang the sides of the multi-wheel flat cars that will carry them.
Of course, if you have a really high, wide, heavy something to move…
You bolt the two ends of a Schnabel car to it, and proceed VERY carefully.
“Loading gauge” is the cross-sectional dimensional envelope that is available to a given railroad line, and is not the same as axle loadings. (You pretty much said that, but many people mix them together, so I want to make that clarification) You’re really asking about both, and they are not in strict correspondence. There are railways with a very large loading gauge and a very low maximum axle loading, and vice versa. A railway with a low maximum axle loading usually dispenses with the cost of obtaining a large loading gauge, but I worked for one sizeable, standard-gauge non-U.S. railway on which all that stood in the way of establishing high-cube doub
Brunel’s Track Gauge was actually 7 feet and a Quarter of an Inch (84.25") but perversely his Loading Gauge wan’t increased proportionately to the Track Gauge.
Next time you’re in the UK, look at the layout at a double-line ex Great Western Station. The minimum gap between the outer rails of adjacent parallel tracks in the UK is 6 feet. When the Great Western was undertaking its progressive "narrowing " of its track back to Stephenson’s Standard Gauge, it was the outer rail that was removed so as to leave the inner rail as before adjacent to the platform, and the one time broad gauge stations are immediately noticeable by the pronounced gap between the respective running lines.
British Railways have a considerably smaller loading-gauge than Continental ones, which in turn have smaller loading gauge than USA/CDN. (I do not know how Spain and Portugal are. Sweden and Norway have spacier passenger-cars than Continental Western Europe). However, axle-load in the UK is IIRC 25 metric tons. In Continental Western Europa, many mainlines have a 22,5 tons, but there are still a lot of 20-ton-tracks on mainlines. The former Soviet-Union had wider gauge and loading-gauge than Continental Western Europa, but quite light tracks.
One minor correction. In Scandinavia, 1525 mm (like the former Soviet Union) applies only to Finland, which has been part of the Czar’s (i.e. Russian) empire from the early 19th century until 1917, i.e. when railroads were built. Denmark, Norway and Sweden run on standard-gauge. Of course, in all the aforementioned countries, there were narrow-gauge-systems for secondary lines. Iceland, AFAIK, has no railroad.
Ireland has it’s own, almost unique gauge of 5’ 3". How this came about is quite a story!
The first railway in Ireland, the Dublin and Kingstown (now called Dun Laoghaire - pronounced “Dun Leary”) was 4’ 8.5". But one or two other lines were built to 6’ 2" gauge (dont ask me where the extra 2" came from!). As the question of gauge had already arisen in Britain, any official from the Irish Office (at this time Ireland was part of the UK) rounded the two gauges to 4’ 6" and 6’ respectively and took the average, which is 5’ 3"! This guy must have had the gift of the Blarney as he persuaded all the lines to convert to 5’ 3"! Thus it became the standard gauge in Ireland; the only other countries it’s found in are certain Australian states (which I believe are gradually converting to 4’ 8.5".) and Brazil.
In the last quarter of the 19th century the UK govt gave subsidies to people building narrow gauge lines in Ireland, almost all of which were 3’ gauge, and as a result one or two lines converted from 5’ 3" to 3’, notably the Cork, Blackrock and Passage line which got a subsidy to extend its line from Passage to Crosshaven and as a result of narrow its gauge was able to double track it’s existing line!