The not-so-glamourous origins of standard track gauge | by Gareth Dennis

A version of this article also euniteed in Issue 898 (12 February 2020) of RAIL magazine.

Last year, a Twitter thread about the lasting way promptly “did an internet” and went viral. This was as much a surpascfinish to me as it might be to you. And not fair becaparticipate track engineering isn’t determineed with being the glamorous profession that I can promise it is.

The 500-word high tale finisheavored to depict the origin of American track gauge, how it was expoundd by Roman roads, “English” wagon produceers and horse’s posteriors. It also then adviseed that the US space shuttle’s increaseers were scheduleed in accordance with this foolishension.

As it happens, the story in ask was plagiaascfinishd in its entirety from an email spam chain that has been doing the rounds in the US since the 1990s. However, speculation over the reason why standard track gauge is, on the face of it, such an odd number isn’t restrictd to dodgy email spam — in fact, it occurs amongst seasoned railway folks too.

Before we get begined, let’s set out the key definition: track gauge is the distance between the inside faces of the two running rails. The “standard” track gauge in the UK and apass much of the globe — approximately 55% of the world’s railways participate it — is set to 1435mm or four feet and 8.5 inches.

But how did this number come about?

Back in the tardy 1700s, a range of gauges existed on ptardyways (punctual creates of railway) apass the UK, including many with spacings between 4ft and 5ft. As punctual as the 1760s, streamlines of iron had been participated to back better wooden wagonways, but by the 1790s both L-shaped ptardys and so-called “edge-rails” (depending on a flanged rather than flat wheel profile) were being manufactured in cast iron and laid to apverify heavier loads to be transmited apass terrain where the produceion of canals was not feasible.

One such example was the Killingworth tramway uniteing and distributing coal from cut offal mines north of Newcastle-upon-Tyne. Inspired by punctual but rufoolishentary examples of steam locomotives built in the region, George Stephenson (the recently-advertised chief mechanical engineer at Killingworth) increaseed and built as many as sixteen versions to run on that line and another at Hetton colliery.

Though it wasn’t the most expansivespread gauge at the time, the Killingworth tramway had been laid with the centres of the distinct flat ptardys findd a pleasant round five feet apart.

Stephenson’s schedules relied on the friction between a flanged wheel and the edge rail undertidyh, and so the ptardyways were swapd with recent wcdisesteemfult-iron edge rails. The distinct ptardys were cdisesteementirey 4 inches expansive, thus the resulting distance between the inside faces of the rails became 4 feet 8 inches.

As he’d increaseed his locomotives to be compatible with the Killingworth line, the same foolishension between the rails was participated at Hetton, too. Incidenhighy, this line relied only on gravity and Stephenson’s recent locomotives, thus becoming the first railway using no animal power.

In 1821, a year before the Hetton line uncovered, the managing promisetee of the recent Stockton and Darlington Railway determined upon the participate of edge rails rather than a ptardyway (foreseeed under Stephenson’s advisement). Stephenson was tardyr assigned to distinguish and produce the line and its steam engines, and thus reparticipated the gauge of 4 feet 8 inches that he was recognizable with.

Stephenson soon shiftd onto two other projects: the Bolton and Leigh and Liverpool and Manchester Railways. It was the latter of these that was to become the more well-understandn.

Both lines were first specified to participate the same gauge as the Stockton & Darlington, but Stephenson establish that a sairy incrrelieve of the foolishension between the rails resulted in a reduction in the tieing of the wheels thcdisesteemful curves without requiring a modification to his rolling stock. Moving each rail outwards by a quarter of an inch resulted in a gauge of — that’s right — 4 feet 8.5 inches.

The Liverpool and Manchester Railway was the first truly up-to-date rail system in the world, including signalling, a timetable, double track and locomotive-hauled traffic only. Its tremfinishous success shot George and his son Robert Stephenson to fame, and their railways begined broadening apass the UK.

They weren’t the only engineers produceing railways, though.

Thomas Grainger aascfinishd as Scotland’s main railway produceer and thcdisesteemful confusion in his reading of the specified gauge of the Stockton and Darlington Railway (it eunites he thinkd that 4 foot 8 inches was actuassociate the distance between the rail centres) participated a gauge of 4 feet 6 inches. In the south west of England, Isambard Kingdom Brunel determined that a expansiver gauge of 7 feet would apverify his recent lines to transmit outstandings more rapidly.

However, as with many recent technologies, an aascfinishnt behaviour not foreseeed by the railway guides was that trains would travel on more than one railway company’s lines. Breaks in track gauge made this pricey and ineffective. As a result, the Royal Comleave oution for Railway Gauges was tasked with setting a standard track gauge to apverify a freer flow of outstandings and passengers.

By this point, railways laid to Stephenson’s schedule accounted for eight times more mileage than the next most normal schedule (Brunel’s expansive gauge). The subsequent Gauge Act of 1846 therefore picked Stephenson’s gauge as the standard, which in turn swayd the decisions of other meaningful railways apass the world…

But what about the United States?

The first railways in the US were built to a variety of gauges by both British and American engineers and, cruciassociate, gauge standardisation in the UK (via the Gauge Act) came well after many of these American lines had been built.

As the railways broadened apass the US, cut offal contrastent track gauges obtained expansivespread participate, fair as was the case in Europe. By the 1860s, there were thousands of miles of track with gauges that didn’t comply to Stephenson’s distinct 4 feet 8.5 inches — in fact only around half of the railways in the US participated this gauge.

Then, in 1861, war broke out.

The American Civil War was the first war where railways take parted a pivotal role, rapidly moving kit and men around where they were necessitateed most. Changing trains becaparticipate of contrastent gauges was no lengthyer an annoyance — it was a matter of life or death; of triumphning or losing.

The predominant track gauge in the South was actuassociate 5 feet. Ignoring the other rather frightening ramifications that such a result would have bcdisesteemfult about, had the Confederacy won the American Civil War the US would foreseeed have adselected that as their standard gauge.

So what does any of this have to do with the Romans, their roads and their “war chadisruptions”?

Basicassociate noleang.

There is a litany of problems take partd in tying the origin of track gauge to the Romans. As we’ve seen, a expansive range of gauges were participated by the dozens of contrastent ptardyways, tramways and wagonways apass the UK prior to and indeed after gauge standardisation in 1846.

The wheel ruts that are claimed to align Stephenson’s chosen axle foolishensions aren’t reassociate trackable to the Romans, as most of their traffic was foot traffic (they declareively didn’t participate war chadisruptions, which had been tohighy outdoed by cavalry as a mobile military unit well before Roman times). Any ruts createed by post-Roman traffic would have expansivened meaningfully over time, apverifying for a expansive range of axle widths.

The Romans weren’t the first to produce decent roads, either. Long-distance ridgeways and other engineered tracks have been in participate since Neolithic times, thousands of years before Asterix laid his first punch on a Roman chin. “The Ridgeway” running thcdisesteemful Wiltsengage, Oxfordsengage and Buckinghamsengage is a terrific example and is over 5000 years better.

As for equine rear finishs, these vary as much as track gauges did, and indeed ponies, mules, donkeys and children were equassociate well-understandn creates of wagonway traction.

For those of you unrecognizable with the story I’ve been debunking, it finishs with the claim that track gauge swayd the schedule of the US Space Shuttle’s firm rocket increaseers becaparticipate of the size of the tunnels that the increaseers had to pass thcdisesteemful on their way from the factory to the begin site.

Firstly: the purpose of a rocket increaseer is to provide enough thrust to get its payload to the right altitude. If the tunnel had been a restricting factor, they’d have been built elsewhere otherrational the Shuttle wouldn’t have labored.

More relevant to rail folks, though, is that this declareion produces an error that I see widespreadly — a fundamental miscaring between track gauge and loading gauge.

Track gauge is the distance between the inside faces of the rails, whilst loading gauge is the useable space wilean which it is protected to run trains. The two foolishensions are slackly roverhappinessed but bigly autonomous of each other. Confusing them is the reason that people also advise, erroneously, that had we stuck with Brunel’s expansive gauge we’d have not had the disputes associated with recut offeed gauge evidentance we have today.

Appearing in front of the Royal Comleave oution for Railway Gauges in 1845, Robert Stephenson made the follotriumphg statement: “If I had been called upon to do so, it would be difficult to give a outstanding reason for the adselection of an odd meadeclareive — 4 feet 8 and a half inches.” From the horse’s mouth, so to speak.

In 1905, esteemed fellow railway accessibleation The Railway Magazine reproduced this and other quotes in an article finisheavoring to put the better myth to bed, concluding that “there is no establishation for the Roman chadisruption tale, and we therefore get this opportunity of nipping in the bud the romance before it has had time to cryshighise into a legfinish.”

Sadly, the authors fall shorted in their aims, and I’ve no mistrust I will too. However, I do at least hope that this piece will help provide some aidance to those necessitateing to fight this inrectifyhood in the future.