Why is 4 feet 8.5 inches the gauge used?

[davekelly]

Mark . . . too funny. Reminds me of my brother in law who makes detailed drawing of beam joints for construction companies. A client called wanting to know why he hadn't got the drawing that were late. After much searching it was discovered that the client's email filtered out the email carrying the drawings because the subject line was "erection drawings."

[marknewton]

Oh dear, looks as though I have transgressed the forum's censorship policy.

The previous post contained a word - eff, ay, gee, gee, oh, tee - that is used to describe a bundle of sticks or rods, in this context a bundle of small diameter iron bars heated in a forge and hammered together to make a homogenous large diameter billet.

Mark.

[marknewton]

QUOTE: Originally posted by davekelly

Good point. But that begs the question - which came first, the rail or the wheel/axle set?

I once read an interesting technical paper that suggested the practical limit for making ***ed
iron axles in the very early days of railways was about five feet in length, and which the author *conjectured* was an influencing factor on the gauge.

I reckon that there is far more likelihood of it being a prosaic matter such as this, rather than some fanciful twaddle about "war chariots", that influenced the early railway builders.

All the best,

Mark.

[marknewton]

QUOTE: Originally posted by modlerbob

You can't articulate an 80' long tube. I live in central Florida and although I can't verify this story I did hear it from several NASA employees after the Challenger explosion.

I agree, you can't articulate an 80' tube. But you can articulate a freight car or cars, which can carry a tube of considerably greater length than 80'. Then you have a dimensional load, which is routed accordingly. The webpage cited outlines the procedures for the movement of dimensional loads on US railroads:

http://www.rica.org/index.html

With the best will in the world, the NASA employees you spoke to were probably not expert in the field of railroad freight car design, hence their thinking that freight cars over 80' long won't go around curves.

Photos of the SRB-carrying flatcars:

http://southern.railfan.net/flat/cars/loads/rocket/rocket.html

Some other images of dimensional loads

http://www.readingnorthern.com/photos/photo66.jpg

http://southern.railfan.net/flat/cars/loads/loads.html?

QUOTE: But I do know part of their PR campaign about the shuttle was that it provided income in over 40 states for various reasons.

I have no doubt that part of the story is true. The various reasons may be summarised as "pork barrelling"!

Cheers,

Mark.

[Anonymous]

QUOTE: Originally posted by marknewton

QUOTE: Originally posted by modlerbob

Another story I've read is that the fact that the SRB's were built in segments instead of one single long tube is that 80' is about the maximum length a rail car can be built and negotiate curves.

How long are modern auto-rack cars? 89 feet? How long are the various types of articulated container cars? How long are the various specialised dimensional load cars? Much longer than 89 feet. Obviously that story is also untrue.

Cheers,

Mark.

You can't articulate an 80' long tube. I live in central Florida and although I can't verify this story I did hear it from several NASA employees after the Challenger explosion.
But I do know part of their PR campaign about the shuttle was that it provided income in over 40 states for various reasons.

Bob DeWoody

[marknewton]

QUOTE: Originally posted by modlerbob

Another story I've read is that the fact that the SRB's were built in segments instead of one single long tube is that 80' is about the maximum length a rail car can be built and negotiate curves.

How long are modern auto-rack cars? 89 feet? How long are the various types of articulated container cars? How long are the various specialised dimensional load cars? Much longer than 89 feet. Obviously that story is also untrue.

Cheers,

Mark.

[davekelly]

Rob,

Good point. But that begs the question - which came first, the rail or the wheel/axle set?

[Anonymous]

I thought it was used because that's how wide the wheels are apart.

[Anonymous]

Another story I've read is that the fact that the SRB's were built in segments instead of one single long tube is that 80' is about the maximum length a rail car can be built and negotiate curves. While it's true that a longer booster could have been built and air transported (the pregnant guppies) there was an attempt at the beginning of the shuttle program to involve as many states and industries in the process to "so to speak" spread the wealth to keep as many congressmen in the yes vote column as possible.

Bob DeWoody

[Anonymous]

Hey... I just want to know what type and weight of rail the Roman chariots ran on! [:D]

[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"[;)]

[Anonymous]

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

South Africa used 42" as their standard gauge. .

[Anonymous]

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

i think greg has nailed it.

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

Greg

[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.

[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.

[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).

[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.

[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.

[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!

[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.

[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.

[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 [:)]

[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.

[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.

[Anonymous]

Time to call in the Myth Busters

James

[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

[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.