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Model Railroading > Mainline Tie Lengths


Date: 02/18/24 23:00
Mainline Tie Lengths
Author: funnelfan

Along with the growth in rail weights which is well documented, mainline tie lengths have been growing with time and heavier locomotives and cars. But I need to verify my time frame for different lengths. I believe prior to WWII the 8' tie was standard, but following the war class 1 railroads began to specifiy 8.5' ties for mainline use. And starting in the 1980's the 9' tie became standard on mainlines? Does anyone have some particular insight to when the longer ties became standard?

Ted Curphey
Ontario, OR



Date: 02/19/24 00:28
Re: Mainline Tie Lengths
Author: shadetree

I thought it was 8 1/2'.  Close to bridges I see them using 10' ones.

Eng.Shadetree



Date: 02/19/24 03:29
Re: Mainline Tie Lengths
Author: Lighter

Is there a national standard? Seems like it would vary by prototype, location, rail weight, and use.



Date: 02/19/24 05:13
Re: Mainline Tie Lengths
Author: doc1057

Standard grade timber crossties are 7"x9"x8-1/2', and have been for well over 100 years. Railroads may use longer ties, but that adds expense; the 8-1/2' length is by far the most common. Of course, crossties in turnouts vary in length depending upon the position and can be considerably longer.



Date: 02/19/24 06:13
Re: Mainline Tie Lengths
Author: engineerinvirginia

doc1057 Wrote:
-------------------------------------------------------
> Standard grade timber crossties are 7"x9"x8-1/2',
> and have been for well over 100 years. Railroads
> may use longer ties, but that adds expense; the
> 8-1/2' length is by far the most common. Of
> course, crossties in turnouts vary in length
> depending upon the position and can be
> considerably longer.

I may be wrong but I think switch ties are not only longer, but overall heavier. At least on my road they have to be heavier because they won't be changed out but every thirty years or so...switch maintenance is a nightmare around here. 



Date: 02/19/24 11:33
Re: Mainline Tie Lengths
Author: doc1057

engineerinvirginia Wrote:
> I may be wrong but I think switch ties are not
> only longer, but overall heavier. At least on my
> road they have to be heavier because they won't be
> changed out but every thirty years or so...switch
> maintenance is a nightmare around here. 

Switch maintenance is always a nightmare!
Generally, most railroads use 7"x9" ties in turnouts just as elsewhere in the track. We've got the standard plans for most of the Class Is, and they all show standard 7"x9" ties in timber tie turnouts. There could certainly be exceptions, because anything you can think of has probably been tried during the history of railroading. But, anything non-standard usually costs more up-front.
Some track owners (industries and some small RRs) cheap out and use so-called "industrial grade" timber ties that are often either 6"x9" or 6"x8". These are seconds from the production process and, while better than no tie, often don't hold up like top grade ties.
As someone else related earlier in this thread, timbers in open deck bridges have different dimensions than regular grade ties and there is much less uniformity there.



Date: 02/19/24 19:40
Re: Mainline Tie Lengths
Author: railstiesballast

For principal main lines the SP used 9' ties in locations with known weak subgrades such as the sloughs around San Francisco and Monterey Bays and 8' elsewhere until the 1970s when all new ties became standardized at 9'.
On branch and yard track the standard was 6"x8"x8'.
Later it became recognized that the 8-1/2' length had a more evenly distributed bending stress and bearing stress on the subgrade that is now, as stated above, the current standard.
For turnouts the "headblocks", which are the long ties that connect the switch stand to the stock rails and points, were 8"x12"x16' and under the frog were 8"x10" of varying lengths, enough to support the rail joints on each side of the frog.  These larger bearing areas were to better resist the wheel impact loads at the frog flangeway gap and at those joints.
In later years when it became well documented that an abrupt change of track stiffness, as when transitioning to a bridge or a road crossing, the severity of the change could be reduced by installing a few 10' ties there as noted above.
I don't think you would have seen these transition ties before the mid 1980s but people with experience on southern or eastern railroads can confirm or edit this.....



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