Why is 4 feet 8.5 inches the gauge used?

[gvdobler]

I saw this in a local garden railway news letter. It had no name as an author but I thought it was good.

DID YOU KNOW?

The US standard railroad gauge (distance between the rails} is 4 feet 8.5 inches. That’s an exceedingly odd number. Why was that gauge used? Because that’s the way they built them in England and English expatriates built the US Railroads.

Why did the English build them like that?
Because the first rail lines were built by the same people who built the pre-railroad tramways, and that’s the gauge they used.

Why did “they” build them like that?
Because the people who built the tramways used the same jigs and tools that they used for building wagons, which used that wheel spacing.

Okay! Why did the wagons have that particular odd wheel spacing?
Well if they tried to use any other spacing, the wagon wheel would break on some of the old, long distance roads in England, because that’s the spacing of the wheel ruts.

So, who built those old rutted roads?
Imperial Rome built the first long distance roads in Europe (and England) for their legions. The roads have been used ever since.

And the ruts in the roads?
Roman war chariots formed the initial ruts which everyone else had to match for fear of destroying their wagon wheels. Since the chariots were made for Imperial Rome, they were all alike in the manner of wheel spacing. The United States standard railroad gauge of 4 feet, 8.5 inches is derived from the original specifications for an Imperial Roman war chariot and bureaucracies live forever.

So, the next time you are handed a specification and wonder what horse’s rear end came up with it, you may be exactly right, because the Imperial Roman Army chariots were made just wide enough to accommodate the back end of two war horses.

Now the twist to the story.

When you see a Space Shuttle sitting on its launch pad, there are two big booster rockets attached to the sides of a main fuel main. These are solid rocket boosters, or SRBs. The SRBs were made by Thiokol at their factory in Utah. The engineers who designed the SRBs would have preferred to make them a bit fatter. But the SRBs had to be shipped by train from the factory to the launch site. The railroad line from the factory happens to run through a tunnel in the mountains. The SRBs had to fit through that tunnel. The tunnel is slightly wider than the railroad track, and the railroad track, as you now know, is about as wide as two horse’s behinds.

So, a major Space Shuttle design feature of what is arguably the world’s most advanced transportation system was determined over two thousand years ago by the width of a horse’s rear end. And you thought being a HORSE’S REAR was a bad thing.

Anonymous

[IRONROOSTER]

Hadn't seen the shuttle twist at the end.[:D]
Thanks for sharing.
Paul

[Anonymous]

Very interesting.

[MAbruce]

Sorry guys, but this is an Urban Legend. Only a small part of it is true.

See: http://www.snopes.com/history/american/gauge.htm

[tatans]

Take a look at Pompeii in Italy, just for fun I paced the distance between the wheel ruts on the sidewalk crossovers and also the distance between the C.P.R. tracks here, hmmmmmm, pretty close (give or take an inch(or cenimetre) or two. so there must be some sort of coincidence here. Also ever wonder why a brick is that dimension, blame the Egyptians.

[davekelly]

I believe that the Roman chariot idea is a bit of an urban legend. The best explanation I heard (and I don't know if it is true) is that the gauge is not that weird of a number. The orginal thought was to have a 5 foot gauge. But given the flanges are on the inside, one needed to measure the gauge from inside the rail to inside the rail. Hense 5 feet minus two rail thicknesses (at the time) came out to 4 feet 8 1/2 inches.

[IRONROOSTER]

QUOTE: Originally posted by MAbruce

Sorry guys, but this is an Urban Legend. Only a small part of it is true.

See: http://www.snopes.com/history/american/gauge.htm

Oh sure. But it's still fun. [(-D][(-D]

Enjoy
Paul

[wjstix]

The 5' story could be true, remember the earliest 'rail roads' often used outside flanges - or used regular wheels and the track had a flange on the outside.

[Tracklayer]

It's human nature to want to believe things that sounds good or that have a good story behind them - whether they're true or not...
However, I did enjoy this story very much - whether it's true or not.

Tracklayer

[icmr]

Very good info.



Victor

Happy Railroading.[swg][swg]

[james saunders]

that is interesting...

[vsmith]

The reality is that 4'-8 1/2" was the ruling gauge at the Darlington & Stockton Coaliary that George Stephenson built the first steam truely successfull locomotive, the Rocket, for. The Darlington Steam Trials competition was the first real attempt to explore steam power on an applied approached and all entries had to fit the existing horse drawn rail gauge, which was 4'-8 1/2" which was the width of the existing line, and not that uncommon among horse drawn lines as one they all tended to copy each other. This was the width that allowed the horse to walk easy and not get tripped up on the rails. This was also before anything we would call "scientific measuring" was ever commonly practiced. Most of these early horse drawn RRs were built by eye, so when they got the wooden rails down they likely had a gauge board to set the rails width that was the result of observed use of what worked with the horses and what didnt. Too narrow and the horses got tripped up, too wide and the wooden axles broke. This is likely that they were also using existing wagon construction practices with the flanged wheels outside the cart frame so that would have been a contributing limiting factor also to where we get 4' 8 1/2 " width also.

When other Coaliers and Mine Operators looked to build in these early RR's almost always they went to Stephenson first, Stephenson already was set up to build at this guage already so invariably he kept it. A couple of the other entries also found homes on similar new RRs built to accomodate these existing locomotives that didnt win the competition. Most other makers followed suit, because once a system was proven, steam locomotion or track system or wheel types, these early engineers would simply copy each other blatently and outright, this is why patent laws were 1st inacted, but even that doesnt help since the same thing happened when the Wrights went public with their aircraft, within 5 years everything they worked so hard to do was blatently copied by engineers around the world, same with electronics today.

[Anonymous]

QUOTE: Originally posted by MAbruce

Sorry guys, but this is an Urban Legend. Only a small part of it is true.

See: http://www.snopes.com/history/american/gauge.htm

Well according to the link you provided it is true after a fashion. 4"-8-1/2" probably wasn't in any Roman specification, but the width of the ruts does fall generally in that range.

Bob DeWoody

[Anonymous]

Time to call in the Myth Busters

James

[orsonroy]

I really hate this urban legend. Nothing in it is remotely correct. Romans didn't use "war chariots", Roman road ruts are anywhere between 4 to 6 feet wide (I've measures several in the UK), horses' butts are usually MUCH wider than 4'4-1/4" (having been raided on a horse farm, I know these things), freight wagon wheel spacings vary hugely from country to country, etc., etc., etc. It SOUNDS good, unless you're a pre-industrial history geek like me, whereupon the whole story unravels fast.

About the only thing that's completely true is the shuttle booster part of the story.

[gvdobler]

Man this is a tough room.

I thought sure I had uncovered the secret of the universe.

Next you guys are gonna say there's no Santa Claus.

[Darick]

QUOTE: Originally posted by orsonroy

I really hate this urban legend. Nothing in it is remotely correct. Romans didn't use "war chariots", Roman road ruts are anywhere between 4 to 6 feet wide (I've measures several in the UK), horses' butts are usually MUCH wider than 4'4-1/4" (having been raided on a horse farm, I know these things), freight wagon wheel spacings vary hugely from country to country, etc., etc., etc. It SOUNDS good, unless you're a pre-industrial history geek like me, whereupon the whole story unravels fast.

About the only thing that's completely true is the shuttle booster part of the story.

This may not be true...but is sure is a fun story [:)]

[marknewton]

QUOTE: Originally posted by orsonroy

I really hate this urban legend. Nothing in it is remotely correct. About the only thing that's completely true is the shuttle booster part of the story.

No, even that part of the story is incorrect...[:)]

All the best,

Mark.

[dinwitty]

we forget that during the early railroad years, there was anything BUT a standard gauge. 3 foot, 5 foot, 2 foot, any in many cases areas where any of these gauges were laid on the same track in multi-gauge.

4' 8 1/2 won out because it could carry more for the number of cars.

[tomikawaTT]

An equally valid (or invalid) claim can be made for the idea that the US standard gauge is 56.5 inches because most of the Civil War was fought on Southern soil and the South eventually lost. (Sorry, Johnny Reb, but that's the way it came out.) In the South, insofar as there was a standard gauge, it was 60 inches (5 feet). As Union forces moved into an area, they would re-gauge the track so that northern rolling stock could use it. Had things been reversed, the standard gauge might have ended up 5 feet.

In the U.K., Brunel built the Great Western to a gauge of 7 feet 1/2 inch - while everyone else was following the Stephenson "coal wagon" (Brunel's words) standard. When 90% of a country's trains run on one gauge and only 10% run on another, guess which one gets changed in the interests of standardization and interchange!

[Pruitt]

Regarding the Space Shuttle SRBs -

I worked on the Space Shuttle early in my career. Thiokol's engineers evaluated a lot of variations in the SRBs - thinner, fatter, taller, shorter, etc. One of the key considerations was that the container car that carries the SRBs have an envelope that didn't exceed railroad standards, so that special routing based on clearances, but it was only a consideration, and not the final size driver. There was a lot more concern over routing and handling restrictions for the loaded SRB cars than there was over sizing the segments.

And there is no tunnel between the factory 30 miles west of Brigham City, UT and the UP mainline in Brigham City.

[marknewton]

At last, someone who has the authority to debunk the SRB part of the story! Hooray for brunton!

(Every time I see this BS tale, I cringe. Why people continue to post it is a mystery to me.)

Cheers,

Mark.

[MAbruce]

QUOTE: Originally posted by Student of Big Sky Blue

Time to call in the Myth Busters

James

Jame - the site I use (Snopes.com) ARE the Myth Busters (or the ones that started that show).

[Pruitt]

Just to add a little more info on the SRBs - what determined the final diameter was the thrust needed as the SRBs approached burnout, which is when the burning surface (the cylindrical face of the exposed propellant) was near its maximum surface area, thus providing maximum thrust (that could also be done with more segments in the stack, though).

Had a larger diameter than what could have shipped by rail been required, a propellant-loading facility would have been built which have had alternative access means to Kennedy Space Center - most likely via barge, same as the external tank.

[Anonymous]

4' 8 1/2" was an accident of history created when lincoln signed the railroad act of 1863. no real thought went into it.

[Anonymous]

I thought they picked 4' 8.5" because that is the exact distance from a damsel in distress' neck down to her ankles.

Greg

[davekelly]

Greg,

Sounds as good as any! lol. Of course I always have this idea that it was meant to be 5 foot but because of either faulty rulers or sloppy workmanship 4 foot 8 1/2 inches it became. . . . kinda like the one time i tried laying N scale track. I had a choice - either use ready to lay flex or start a new sub-group Nn55-58. N scale variable guage.

[Anonymous]

i think facts tend to get in the way of a good story.

i think greg has nailed it.

[Anonymous]

To sum it up, Russian railroads used the 5" gauge, so not everone agreed.

South Africa used 42" as their standard gauge. .

[vsmith]

QUOTE: Originally posted by bangert1

To sum it up, Russian railroads used the 5" gauge, so not everone agreed.

South Africa used 42" as their standard gauge. .

5 " gauge, wow thats what I call "narrow gauge"[;)]