4.1.4 Rail

Roadbed is composed of three principal parts: the rail, on which the trains run; the ties, which hold the rails to gage 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 rails.

Prototype Information

Composition of Rail

The history of rail in the United states begins in the early 1830s with strap rail, that is iron straps screwed onto wooden rails. While crude, it worked until the weight of the steam engines caused the iron straps to separate and curl upward. Iron rail of similar configuration of todays T rail was of some improvement. It wasnt until the advent of the Bessemer steel process in 1860 that rail became an asset rather than a liability in railroad operations. 

The composition of the steel rail is : iron, carbon, magnesium, phosphorus, silicon and sulfur.  A steel containing these elements is called carbon steel. The specific requirements of the rail determines the compositional ratios of these elements.

Rail Cross-section. There were a variety of rail cross section, between 1860 and the advent of the ASCE (American Society of Civil Engineers) first standardization of rail cross section. For our purposes, there are two engineering standards: AREA (RE) and ARA.

ASCE and AREA rail cross sections

 

ARA rail cross sections

 

Rail Size. Prototype rail is sized based on weight per foot yard.  It started with 50 pound rail and has increased over the years to 155 pound rail used today.

In the web site Modeling the Reading in Proto 48. George Losse has an excellent post called Table of Weights & Dimensions of Rail. The post has a document published by the AT&SF Railroad called Table of Weights & Dimensions of Rail. This document has no date but it runs 12 pages and contains the dimensions and sizes of rail made by Illinois Steel Company, Carnegie Steel Company, Pennsylvania Steel Company, Bethlehem Steel Company, Lackawanna Steel Company, Cambria Steel Company, Colorado Fuel & Iron Company and Dominion Iron & Steel Company. I didn't know how many possibilites there were in manufactured rail.

Rail length. Rail length was originally 30 feet. It was increased to 33 feet early in the 20th century. 39 foot rail was adopted as standard by the AREA in 1937. The longer the length of the rail means fewer joints, with reduced joint-troubles. Standard rail manufacturing contracts usually permitted acceptance of about 11 percent short rails varying down to 25 feet for use in curves and switch connections.

Life and Wear. The life of rails of the same weight and section and under the same traffic varies considerably because of different quali­ties of the metal. Besides the chemical composition and method of manufacture, the wear of a rail depends upon whether the rail is placed on a tangent or a curve, on the outer or inner side of a curve, or on a steep grade. Even when a rail is so worn that it is no longer fit for service, the actual proportion of metal lost by wear is comparatively small. Sound worn rails can be heated in a reverberatory furnace and rerolled into new rails having a lighter section than the old rails. This rail is classified as re-rolled rail. 

Rails are usually removed from the main track when so worn that the following conditions exist: when the splice-bars are being cut or struck by the wheel-flanges; when the side of the head is worn as much as one-­eighth the original width or when the side of the rail-head is worn to the shape of the wheel-flange and fillet so that the wheels are liable to mount the rail; or when the top of the head is worn 1 in. 

The percentage of the area of the cross-section which can be worn away to produce the above conditions depends upon the type and weight of rail. Rails on tan­gents and on the inside of curves wear mostly on the top of the head. Rails on the outside of curves wear mostly on the side of the head. 

Rail Failures. Practically all rail failures are the result of defects in the rail due to faulty manufacture. These defects are not noticeable in the newly laid rail, but under the action of traffic they are gradually accentuated until failure occurs or the defects become noticeable. 

During the past few years failures have received much study and investigation in an endeavor to ascertain their primary causes. The American Railway Engineering Association has prepared seventeen stand­ard blank forms for recording the life history of a rail from the time the ingot is cast, through the period of manufacture, tests, inspection, shipment and service in track, until the rail is finally removed from track because of natural wear or premature failure. 

A rail is removed from the track for one of the following reasons:

1. Flow of metal of the head
2. Split web.,
3. Crushed head.
4. Split head.
5. Transverse fissure (oval spots in rail-head).
6. Broken rail (square and angular breaks).
7. Broken base (crescent breaks).
8. Damaged rail.
9. To be replaced with heavier rail.
10. Normal wear.

Classification for Track Purposes. Each railway classifies rail according to the use made of them in the track. Second-class and short rails are not allowed in high-speed tracks but may be used in low ­speed tracks, switch leads and yard-tracks. 

The Canadian Pacific Rail­way classified rails as follows: 

  1. New rails. All rails not previously in service.
  2. Main line relay rails. All second-hand rails not less than 24 ft. long, provided the rails are sound throughout; if curved, can be straightened with a rail-bender when necessary, and which show a wear not in excess of the following: A vertical wear on top of head of 7 in. for 80- and 85 lb. rail and 16 in. for 100-lb. rail; wheel-flange wear of head of ½ 6 of the original width; a wear under the head that will leave not less than ¼ fo. between the angle-bar and the web of the rail; ends bent down He in. in a length of 2 ft. or less.
  3. Branch line relay rails. Any rails not less than 20 ft. long that are sound throughout, which, if curved, can be straightened with a rail-bender when necessary, and which show a wear not in excess of the following: A vertical wear on top of head of ¾ in. for 100-lb. rail, ¾ in. for 60- to 85-lb. rail and ¼ in. for 56-lb. rail; a wheel-flange wear of head of one-eighth of the original
    width; a wear under the head that will leave not less than Yte in. between the angle-bar and web; ends bent down ,{ 6 in. in a length of 2 ft. or less.
  4. Siding rails. All those unfit for main or branch lines, but which still have service left in them. These include rails with badly battered ends, rails with broken flanges that can be strengthened by using angle-bars, and piped rails. These must be·not less than 15 ft. long.
  5. Scrap rails. All those which are twisted or bent and cannot be straightened; pieces of all rails less than 6 ft. long; rails from which the following serviceable lengths cannot be cut: 80-, 85-, and 100-lb., 11 ft.; 72- and 75-lb., 14 ft.; 65-lb. or less, 6 ft. 
  6. Rail-rack rails. Rails distributed on rail-racks.
  7. Auxiliary and emergency rails. All rails loaded on auxiliary cars for emergency purposes.

Rail usage.

Great Northern. In 1935, The Great Northern used 9 rail sizes, from 70-lb. to 130-lb. Most of the primary and secondary main line track (74%) was 90-lb. It had been in service for about 11 years. Most of the branch line track (60%) was 70-lbs or less. It had been in service 41 years. Some 100- and 110-lb. rail was installed as an upgrade to the 90-lb. rail. 130 -lb. rail was used on high trafficed main line curves and in tunnels. Its longer life made its use desireable as it decreased the frequency of renew requirement as compared with lighter sectional weights.

Northern Pacific. The 1970 Track Charts for the Tacoma Division's 16th Subdivision (Grays Harbor Line) shows 112 lb rail.

Milwaukee Road. A valuation report from 1925 identified that the Milwaukee Road used 75 and 85-lb. rail on the upgrade of the Tacoma Eastern line.

Union Pacific. Common Standard documents show the Union Pacific was using 90- and 100-lb. rail in 1926, 110-lb. rail in 1937.  A track map of the joint UP/MILW roadway at Preachers Slough showed that 90-lb. rail was installed in 1927, in other locations on the branch line second hand 90-lb rail was installed in 1939.

Modeling Information

Model railroad rail size is not based on weight of the rail but the height of the rail. It is advertised as 'code'. Common sizes are code 100, code 83, 70, 55, and 40. For example, code 83 is .083” tall.  Railroad modelers sometimes desire to mix different track sizes in accordance with prototype practice, in other words join a section of one code rail to a rail of a different code.  For instance, you may want code 83 on your main line and code 70 for your industrial  tracks.

Code v rail weight. Rick Blanchard took the data from the 1939 American Railway Engineering Association standards for rail sizes and converted it to the equivalent scale sizes. Looking at the chart, the numbers refer to the 'code' rail that would fit best. For example, the chart shows 110 pound rail in N scale to be 0.039, and the closest 'code' rail would be code 40. 

    Ratio 220 160 120 87.1 76.2 64 48 32 24 20.32
    Scale Z N TT HO OO S O #1 1/2" F
Standard Weight Height                    
PRR 155 8.000 0.036 0.050 0.067 0.092 0.105 0.125 0.167 0.250 0.333 0.394
AREA 140 7.312 0.033 0.046 0.061 0.084 0.096 0.114 0.152 0.229 0.305 0.360
AREA 132 7.125 0.032 0.045 0.059 0.082 0.094 0.111 0.148 0.223 0.297 0.351
AREA 115 6.625 0.030 0.041 0.055 0.076 0.087 0.104 0.138 0.207 0.276 0.326
AREA 100 6.000 0.027 0.038 0.050 0.069 0.079 0.094 0.125 0.188 0.250 0.295
AREA 90 5.625 0.026 0.035 0.047 0.065 0.074 0.088 0.117 0.176 0.234 0.277
ASCE 85 5.188 0.024 0.032 0.043 0.060 0.068 0.081 0.108 0.162 0.216 0.255
ASCE 80 5.000 0.023 0.031 0.042 0.057 0.066 0.078 0.104 0.156 0.208 0.246
ASCE 75 4.812 0.022 0.030 0.040 0.055 0.063 0.075 0.100 0.150 0.201 0.237
ASCE 70 4.625 0.021 0.029 0.039 0.053 0.061 0.072 0.096 0.145 0.193 0.228
ASCE 65 4.438 0.020 0.028 0.037 0.051 0.058 0.069 0.092 0.139 0.185 0.218
ASCE 60 4.250 0.019 0.027 0.035 0.049 0.056 0.066 0.089 0.133 0.177 0.209
ASCE 55 4.062 0.018 0.025 0.034 0.047 0.053 0.063 0.085 0.127 0.169 0.200
ASCE 50 3.875 0.018 0.024 0.032 0.044 0.051 0.061 0.081 0.121 0.161 0.191
ASCE 45 3.688 0.017 0.023 0.031 0.042 0.048 0.058 0.077 0.115 0.154 0.181
ASCE 40 3.500 0.016 0.022 0.029 0.040 0.046 0.055 0.073 0.109 0.146 0.172
ASCE 35 3.312 0.015 0.021 0.028 0.038 0.043 0.052 0.069 0.104 0.138 0.163
ASCE 30 3.125 0.014 0.020 0.026 0.036 0.041 0.049 0.065 0.098 0.130 0.154
ASCE 25 2.750 0.013 0.017 0.023 0.032 0.036 0.043 0.057 0.086 0.115 0.135

The WWSL 

The WWSL will use generally use prototype rail practices on paper only (engineering diagrams). There will be some actual rail practice, those exceptions will be noted as they occur.

  • NP. the Grays Harbor Branch (16th Sub) would have no more than 112 lb rail. I will assume that the rail would have been 90 lb in the 1950's. (Code 70). This rail would be located on the main line track at Brady Junction.
  • Milw/UP the Grays Harbor Branch (16th Sub) would have 90 lb rail (code 70). This rail would be located on track at Chehelis River and Preachers Slough.
  • WWSL. The WWSL would realistically have 90 lb rail (code 70). Alternate history would suggest that with the coal and stone traffic on the Northern Division and the new Southern Division main line that the WWSL would have have pugraded to 132 lb rail (Code 83) for maintenance simplification. Exceptions will be high trafficed main line curve switches (Code 100).
  • OPLC. The OPLC would have at least 3 rail profiles, 65 lb, 75 lb and 85 lb (code 55). There is no manufactured turnouts for code 55 track, requiring all track and turnouts to be hand laid. To simplify standardization in track laying (and avoiding having to have special order locomotive wheels on OPLC's steam engines), I have opted to have all OPLC trackage in code 83, less vignette scenes which will have code 55 or code 70 rail.
  • STC. The STC would have rail profiles similar to the OPLC (65 lb, 75 lb and 85 lb). As the STC has a new yard at Wickwood to service the American Pulp and Paper company, and has used WWSL MOW assets in laying that yard, it will have 132 lb rail (code 83), less vignette scenes which will have code 55 or code 70 rail.

Reference

Great Northern Historical Society Reference Sheet No. 41

Northern Pacific Track Charts

Milwaukee Road MOW



 

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