Why is 4 feet 8.5 inches the gauge?

[gvdobler]

I saw this in a local garden railway newsletter with no author named.

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

[CSSHEGEWISCH]

The story about ruts for Roman chariots is the most common story for explaining why standard gauge is set at 4' 8.5". The Russian gauge is 5' for military reasons: anybody invading from the West can't use their rail equipment on Russian rails.

I would like to hear the explanation for the British Imperial gauge of 3' 6".

[TomDiehl]

Another one of the colorful "urban legends," unfortunately pure speculation.

The more BELIEVABLE story about standard gauge: The first railroads in the US were built with the flanges on the outside of the wheels, not inside as today. The gauge of the rails was set at 5 feet measured on the OUTSIDE of the rail. Experience and experimentation showed that wheels with flanges on the inside operated more reliably and safer than outside flanges. Rather than change all the rails already laid and make all new axles to change cars and locos to the 5 foot gauge measured on the inside of the rail, they opted to simply to remove the wheels and turn them around on the axles. The wheel treds were an average of 1.75 inches wide, so when the two wheels were reversed, the gauge was 4 feet, 8.5 inches (1.75 times 2 wheels, subtracted from 5 feet)

Then there's also the speculation that standard gauge was set when the US government set the standards for the companies building the first transcontinental railroad. They simply took an average of the existing railroads in the US at that time.

Unfortunately, the TRUE story has been lost to history.

PS: A railroad tunnel is a BIT wider than two horses butts.

[nssr9169]

LIKE SAID ABOVE THEY ORRIGINNALLY MEASURED TRACK GUAGE FROM THE OUTSIDE OF THE TRACKS BUT WITH THE RANSITION TO INWARD FLANGES THEY STARTED TO MEASURE THE INDIDE GUAGE, but i highlly doubt that it is 5ft. from outside to outside of the rails due to the heavy poundage (yes that is a correct turm) or hevy gauge if you want to call it.

[Anonymous]

back in the 1860's all the gauges were represented.

when president lincoln signed the railroad act of 1863 it was mentioned that the gauge would be 4' 8 1/2". this was so when the union and central pacific met they would match up.

since this was the first reference to an "official gauge" that got nationwide exposure; everybody else building a railroad followed suit.

[tpatrick]

Not quite everybody followed suit. Erie was originally 6 foot gauge. It actually took a while for them to realize their mistake. The line was completed to Dunkirk in 1851 and it wasn't until 1876 that they decided to go to standard gauge. Initially they laid a third rail to standard gauge and operated for a while as a dual gauge line. By December 1878 Erie was a three rail railroad from Jersey City to Buffalo. In spring of 1880 they began removing the outside rail and in about 18 months the Erie was a standard gauge railroad. The legacy of a quarter century of six foot operations was high and wide clearances, for which Erie was famous.

[Jack_S]

QUOTE: Originally posted by gvdobler

I saw this in a local garden railway newsletter with no author named.

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.

Anonymous
[/blue]

This bit about the "Imperial Roman war chariots" is totally bogus. The use of chariots for war was already obsolete during Alexander the Great's campaign against Persia in the 4th century BCE. By the time anyone wrote about Roman war practices they were almost exclusively infantry with a small cavalry contigent, but no chariots.

The only thing Romans of the Republic and the Empire used chariots for was racing in the Circus Maximus, for the Triumphal parade of a victorious general, and for some religious ceremonies, like the selection of the October Horse for a year-end sacrifice.

When he invaded Britain the first time, Julius Caesar's legions ran into the use of war chariots by the Britons and, at first, had trouble coping, since they had never seen anything like that. However, they quickly worked out tactics that defeated the charioteers and they pressed on successfully.

And it is for darned sure that, if the Republic didn't use chariots, the Empire never even thought of it. Most Roman roads were made of a width that permitted a squad of Legionaries (8 men) to march comfortably abreast.

[Anonymous]

I think its because that the size most locomotives and cars fit on!