Buster Keaton holding an old tie in “The General“, 1927. Note that the bases of the rails have cut into this tie under heavy traffic, tie plates having not been used.
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.
With most cars weighing about 60-75 tons in 1956 on the line that I’m modelling, standard gauge (4′-8 1/2″ or 1435 mm) track in the era that I am modelling used ties eight feet long. Here are some specs from the Canadian Pacific Foundation Library’s Factors in Railway and Steamship Operation from 1937.
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 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 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 1 ties are used on main lines and on curves on first class branch lines.
Number 2 ties are used on tangent tracks of main lines, on branch lines, and on sidings.
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”.
Ties were commonly of untreated timber, cedar being a favourite for its rot resistance. As railway equipment got heavier, rails cut into the ties under the added weight, producing the tie wear seen in the above photo. 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. Stands of cedar thinned out, and cedar was found not to hold up well under higher railway equipment loads anyway. 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 from 1906 on CP. Creosote won out over all others, CP using zinc chloride treatment on its Western Lines’ ties in areas of low rainfall. By 1937, CP estimated an average tie life of 26 to 31 years, untreated ties costing $1.30 per tie installed in track, with treated ties costing $1.90.
Next time, I’ll look at ways to model ties for handlaid track in HO scale.
Scale 8″ wide ties in Lindsay’s Durham Street yard. Ties were laid using a piano-key tie spacing jig.