Width of an NMRA Standards Gage

Model Railroader Layouts and layout building
1

Yup. “Gage”. That’s how it’s spelled on my NMRA standards gage.

Anyway.

In the topic “Yard Track Spacing and Radius…”, there has been some discussion on how wide the Standards Gage is.

Mike said first that his was 2 3/16" wide.

I said that I felt differently–that it was 2 1/16" wide. I just measured mine again (a MARK IVb) with a micrometer, and it is 2.063 wide. That’s 2 1/16".

That’s an eighth of an inch difference! For a GAGE!

Very curious, I thinks. I just checked the NMRA Recommended Practice for this dimension, and got 2 X 1.10", or 2.20". THIS is very close to the 2 3/16" reported by Mike and others.

And yet, I’m holding an official NMRA gage that says different.

At least online, it doesn’t appear that NMRA keeps historical information about any dimension changes over time.

However, it so happens I have copies from Olden Times. The dimension under discussion was shown as 2 X 1", or 2", in a 1959 copy of Standard S-8.

So, over time, we have a Standard Dimension changing, without notation in the Standards. And/or the Recommended Practices.

To date, I’ve never used my various NMRA Standards Gages to check this dimension.

I’ll note here that the current 2.2" matches the structure clearances noted in both Washington and Oregon railroad clearance standards from the fifties.

I post this topic to explain the differences reported in the other topic, and to reveal a certain fluidity in NMRA standards, generally undiscussed. I should dig out my OLD NMRA gage, buy a new one, and build a display of “NMRA Gages over the years”.

Ed

2

Ed

I guess I’m kind of behind the times mine is a Mark II gage and it is 2" wide

3

You’re sitting on a FORTUNE, man. DON’T loose that!

No. Wait.

Can I have it for my collection?

Ed

4

When I was building one of my camera cars I made a CAD drawing to scale of my NMRA Gage using my digital caliper.

It was very helpful with the design of the car.

I was able to keep the camera movement within the needed clearance of my tunnel portals.

Mel

Modeling the early to mid 1950s SP in HO scale since 1951

My Model Railroad
http://melvineperry.blogspot.com/

Bakersfield, California

Aging is not for wimps.

5

[quote user=“7j43k”]

Yup. “Gage”. That’s how it’s spelled on my NMRA standards gage.

Anyway.

In the topic “Yard Track Spacing and Radius…”, there has been some discussion on how wide the Standards Gage is.

Mike said first that his was 2 3/16" wide.

I said that I felt differently–that it was 2 1/16" wide. I just measured mine again (a MARK IVb) with a micrometer, and it is 2.063 wide. That’s 2 1/16".

That’s an eighth of an inch difference! For a GAGE!

Very curious, I thinks. I just checked the NMRA Recommended Practice for this dimension, and got 2 X 1.10", or 2.20". THIS is very close to the 2 3/16" reported by Mike and others.

And yet, I’m holding an official NMRA gage that says different.

At least online, it doesn’t appear that NMRA keeps historical information about any dimension changes over time.

However, it so happens I have copies from Olden Times. The dimension under discussion was shown as 2 X 1", or 2", in a 1959 copy of Standard S-8.

So, over time, we have a Standard Dimension changing, without notation in the Standards. And/or the Recommended Practices.

To date, I’ve never used my various NMRA Standards Gages to check this dimension.

I’ll note here that the current 2.2" matches the structure clearances noted in both Washington and Oregon railroad clearance standards from the fifties.

I post this topic to explain the differences reported in the other topic, and to reveal a certain fluidity in NMRA standards, generally undiscussed. I should dig out my OLD NMRA gage, buy a new one, and build a display of “NMRA Gages over the years”.

Ed

[/quote

6

I wish $10 on evilbay

7

Mine is a Mark V.

Measured with a Zona tools square.

8

As equipment widths on the prototype has changed over the years, the NMRA has changed their standards gage as well. Some of the changes were done to reflect prototype changes, and some were done to reflect NMRA Standards changes. Equipment has gotten somewhat wider over the years. So has the gage.

So it isn’t surprising that different variants of the gage have different dimensions (otherwise, why would there be different variants in the first place?).

9

Mark,

Equipment has NOT gotten wider over the years.

In 1955, Plate B (the only one shown in my ORER) width was 10’-8".

In 2015, all Plates showed a maximum width of 10’-8".

I expect the widening of the gage was done for good and thoughtful reasons. But it wasn’t done because the prototype got wider.

Ed

10

I don’t know, but my guess is that as longer rolling stock became more widely used, and modelers developed a robust market for large steamers, it became necessary for ‘recommended’ clearances to reflect a wider safety margin irrespective of actual prototype dimensions and practices. A responsive governing body will listen to feedback and complaints about a protocol’s or a device’s deficiencies, and they’ll make adjustments so that those things offer more utility to their constituency and membership.

11

Mine is a Mark IV.

Does anyone have a link to the instructions for how to use it? I think that would be very helpful. I have a feeling some contributors are are not using the gage the same as others, or maybe we are talking about something the gage is not even intended to be used for.

I do not use my gage to check clearances. I use an 86 foot high cube boxcar for that. I space my tracks wider than NMRA recommendations for finger clearance.

-Kevin

12

That’s what Hersheys and others do with candy bars. A Snickers was 5 cents. They made it bigger and charged 10 cents. Then they made the 10 cent bar smaller again, etc. Expect the next NMRA gage version to be smaller but cost the same, then a larger, more expensive version a few years after that, and so on.

Or, it’s like fashion for (wearable) ties: wide ties are in, skinny ties are then in, then wide ties again, etc.[:D]

13

Here’s the official directions:

https://www.nmra.org/sites/default/files/standards/sandrp/pdf/rp-2_2019.07.07_typo_correctiontrack_gages.pdf

I see there are some videos on the subject, too.

Ed

14

Longer rolling stock isn’t involved here, as we’re talking about a gage that’s designed for straight track. It’s the width, only.

Yup, there’s a robust market for large steamers. But I doubt that their overall width is significantly greater than “medium” ones. That’s a tougher one to nail down though. I just paged through a diagram book for SP&S steam, and the railroad didn’t list extreme widths. They must have thought it unimportant.

Ed

15

Thanks Ed.

It looks like what I thought was correct. The total width of the gage is not used for checking anything.

Am I missing something?

-Kevin

16

You use the “total width of the gage” to check for NMRA horizontal clearance on straight track.

Considering that the width of the MARK V gage mirrors almost exactly the required clearances in Washington and Oregon (and likely elsewhere), it’s not totally useless. It’s also good for having a place to put all the notches and bumps.

That funny little notch on the left is to check platforms.

Oh. It turns out the MARK II Standards Gage was issued in the early sixties, to reflect the new RP25 flanges. I doubt the MARK I was marked with a “I”. I MIGHT have one somewhere. I MIGHT have lotsa things. Somewhere.

Pretty sure I’ve got a MARK II.

Ed

17

I missed that part. It must be in one of the detailed RP pages.

I wonder why they did not put a lettered measurement on the full width and reference the specific RP like they did for other dimensions.

Maybe that is what dimension “A” is, just doubled for both tracks.

-Kevin

18

I’m not sure it is. But that is definitely what it is supposed to be.

dimension A is the distance from track centerline to minimum clearance. 2 X A is for the full width.

Ed

19

Thanks Ed. I think I got it now. I appreciate the help and clarifications.

However, I think I will stick to using the big Athearn High Cube for clearance checks. It is larger than any other train car I will ever run, so if it is good, all is good.

-Kevin

20

That’s all well and good Ed, but…

Did you check 1925? 1880? or are you saying that modern equipment is essentially the same width as 1880’s equipment? Or 1930’s equipment? (Railroading did exist before 1955, you know [;)]).

Prior to the 1950’s, I believe equipment was generally a bit smaller (when boxcars were commonly single-sheathed wood siding on steel frames, or when most cars used truss rods, as examples). Either that or I have a bunch of badly undersized early 20th-Century-to-WWII rolling stock. [:o)]

But I take your point about the more recent decades.

For the modern era, here’s how a few of the different prototype railroads define over-width loads.

BNSF:

Machinery & Oversized Shipments | BNSF

Note that a load isn’t considered oversized (in width) until the width is more than 11 feet. That’s 4" OVER your 10’-8" quote.

UP (same as BNSF): UP: Seven Steps to Shipping Dimensional Loads

Interestingly, CSX over-width size is your stated 10’-8". Dimensional/Clearance - CSX.com.

NS goes even farther. Any dimensional load over 10’-6" requires special attention.

In any case, the standards gage has changed over the years, for