Roadbed is composed of three principal parts: the rail, on which the trains run; the ties, which hold the rails to gauge and distribute the load from them to the ballast; and the ballast, which holds the ties in line and surface and distributes the load from the rails, through the ties, over the roadbed.
This page discusses prototype and modeling ties.
Prototype Information
If rails were laid directly upon the ballast, they would soon sink into it under the weight of traffic. The contact area of a railway car wheel upon a rail is about the size of a dime. A car weighing 80 tons has eight points of contact on the rails, each point carrying ten tons. Ties are an integral part of railway track structure to reduce the load of railway equipment upon the rails to a surface pressure that will allow for track to be laid on the earth or ballast. Otherwise a solid surface would need to be laid such as reinforced concrete to carry the rails and the load transmitted from rail to the ground.
Tie specifications
Each railroad had their own tie specifications based on their geographic area, the type of roadbed being constructed, and the type of traffic used on the railroad line.
The following is the specification for railroad ties for the Canadian Pacific Railway
Number 1 ties are 7 inches thick. If flatted, they must have from 7 inches to 12 inches face. If squared, they must be 9 inches wide, with one inch of wane permitted on two corners on one side only. Number 1 ties are used on main lines and on curves on first class branch lines.
Number
2
ties are 6 inches thick. If flatted, they must have from 6 inches to 12 inches face. If squared, they must be 8 inches wide with one inch of
wane permitted on two corners on one side only. Number 2 ties are used on tangent tracks of main lines, on branch lines, and on sidings.
Number 3 ties,
or merchantable culls, are larger or smaller than specified above, which, due to improper manufacture or excessive wane, requires that they
be excluded from the number one and number two grades. In practice, Number 3 ties are accepted when their face measurement is not less than 5
inches. Number 3 ties are used on sidings and spurs.
* The
squared ties referred to were usually sawn on all four sides in a sawmill. “Flatted” ties could either be sawn on two sides in a sawmill
or “hewn by skilled woodsmen with axes and saws”.
The Great Northern Railway had three grades of ties: Number 3s - 6" x 8"x 8'6", Number 4s - 7” x 8”x 8’6”, and Number 5s - 7” x 9”x 8'6". Sawn ties were considered standard grade ties and used for all main line tracks, hewed or slabbed ties were considered inferior grade ties and used for yard tracks, storage, repair and spur tracks.
The Northern Pacific
The Union Pacific had one class of ties: 7” x 9”x 8’. The tie lengths were increased in the late 50's to 7” x 9”x 8’6”, and later to 7” x 9”x 9’.
Milwaukee Road
Turnout ties.
Great Northern
Northern Pacific
Union Pacific.The Union Pacific specified mainline ties of 7” x 9”, in lenths from 8'6" to 16'.
Milwaukee Road
Bridge-ties.-A common size of bridge-tie is 8 in. by 8 in. by 9 or 10 ft.
The Great Northern Railway had 4 grades of bridge ties: Number 3s - 8" x 8" x 10' and 12' lengths, Number 4s - 8” x 10”x 12' and 16' lengths, and Number 5s - 8” x 12” x 12' and 16' lengths. For turntables - 8” x 14” x 14'6" lengths.
The Northern Pacific
The Chicago, Milwaukee and St. Paul specified 8-in. by 8-in. by 10-ft. ties. The spacing of the ties depends upon the size of tie and design of the bridge or trestle.
The Union Pacific specified ties 8" x 8" x 9' long. Tie spacing was spaced bridge ties 12" center to center.
Tie Treatment
Ties were commonly of untreated timber, oak for its hardness and
cedar being a favourite for its rot resistance. As railway equipment
got heavier, rails cut into the ties under the added weight, producing deterioration under the rail. Tie plates spread the increased
weight between rail base and tie out over a larger area under the rail
and eliminated tie failure due to rail cutting. Ties installed in track were lasting ten
years or less before having to be replaced.
The solution was to
treat ties with some kind of preservative. Several different types and
processes were tried: creosote, zinc chloride and zinc-meta arsenite. Generally creosote won out over all
others, with zinc chloride in
areas of low rainfall.
Tie Life. Tie life is influenced by track class, tie plate protection, ballast and good drainage. The Great Northern experience with tie life was 25 years and up for creosoted ties, 18 years for zinc chloride treated ties, an untreated ties of 12 years or longer. .Other railroads experiences with tie life varied.
Tie Spacing. The spacing of ties are functions of the condition of track and traffic. An easier riding track results from the use of smaller ties placed close together than from larger ties spaced farther apart. As the spacing is decreased, two advantages are obtained. First, the unit pressure of all track materials is decreased and, second, the carrying capacity of the roadbed is increased correspondingly. The minimum spacing should not be less than the width of track-shovels used.
 | |
| Union Pacific Tie Spacing |
Great Northern
Yard, passing and thoroughfare tracks: Class A 13-in., Class B 14-in., Class C 18-in.,
Storage, repair and spur tracks: Class A 22-in., Class B and Class C 2-in.,
Northern Pacific
Milwaukee Road
Union Pacific. See Figure on the right.
Modeling Information
Railroad Modelers have four ways of laying track. There is 1) sectional track, 2) flexible track where the rails and ties are assembled together, 3) tie strips (ties only) and 4) handlaid track
- Atlas has 9" straight track and various radii curved sections. I dont know what the tie size is.
- Atlas, Peco, and Walthers / Shinohara has flexible track. The Shinohara track has 6” x 9”x 8’6” ties. Spacing is adjustable when the plastic web is cut.
- Central Valley has flexible tie strips. One strip has 7” x 9” x 9' ties with a spacing about 21" (Mainline) and another strip has 6” x 8”x 8' ties (Branch line) with a spacing about 21". Micro Engineering has a flexible tie strip 7” x 8”x 8'6" ties. Micro Engineering HO Code 83 Bridge Flex-Trak has 1.37" (10 ft.) long ties. The spacing of the ties depends upon the size of tie and design of the bridge or trestle.
- Mount Albert Scale Lumber has 7” x 9” x 8'6" wood ties, 7” x 9” x 16' turnout ties and 8” x 8” x 10' bridge ties. Kappler Lumber has 7” x 9” x 8' and 7” x 9”x 8'6" wood ties, 7” x 9”x 16' turnout ties and and 8” x 8”x 10' bridge ties.
The WWSL.
Common Standard. The WWSL Maintenance Of Way department has standardized tie spacing based on the Union Pacific Tie Spacing Common Standard. The WWSL will use Walthers / Shinohara flexible track as the basic for trackage. See 4.2.11 Roadway Modeling Techniques for tie spacing standards.
Bridge Ties. The WWSL will use Walthers / Shinohara, Central Valley and Micro Engineering bridge ties as appropriate to bridge type and era built.
Wood Ties. The WWSL will use wood ties for abandoned track, tie piles, etc. on vignettes. See 4.2.13.1 Modeling Wood Ties for tie detail modeling and coloration techniques.
See 4.1.3.2 Tie Storage for prototype tie storage modeling techniques.
See 4.2.12 Painting Track for tie color guides and techniques.
Circuit board ties. The WWSL will use printed circuit board ties at section breaks, for turnout gauging, and other locations as operationally necesary. Clover house has copper clad circuit board strips that can be used for 6” x 8”, and 6” x 9” ties.
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