The railways of the United States on January 1, 1947, compaised of 1,168 companies, with an investment of approximately $28,000,000,000. The point-to-point mileage of the railways in the continental United Atates was approximately 226.700, with a total operating trackage of about 397,700 miles.
Of the 226,700 total miles of road there were 170,000 span bridges, 401,000 culverts and arches, and 14,000 overhead highway and pedestrian bridges. The value of of all those structures awas estimated at $2,000,000,000, with an annual expenditure ofr maintenance averaged ov er 39,000,000,000.
During 1946 ,the railroads moved a larger volume of traffic than in any other peace-time year - The Class 1 line-haul railways alone carrying 502,000,000,000 tone-miles of freight and and 65,000,000,000 passenger-miles. The total operating revenue on these roads was slightly more than $7,000,000,000.
1946 was cidered a year of 'profit-less prosperity'" for the railroads, because taxes, amounting to almost $500,000,000, and and operating expenses of nearly $6,500,000,000 absorbed a larger proportion of the gross revenue than in any other peace-time year. Railway operating income in 1946 showed a decline.
With the exception of the two preceding years, the average number of railway employees in 1946 - about 1,359,000 was greater than any other year since 1930. Of that total,about 265,000 were maintenance of way and strucures employees.
Roadway Engineering.
Walter Mason Camp in his book Notes on Track, discusses the subject of roadway engineering. Roadway engineering begins with the reconnoissance or preliminary surveying of a route and follows through the location and the construction of the roadbed, the building of the track proper, and continues with the maintenance and repairs ever afterward; for in no sense can it be excluded during the progress of any of these steps.
In locating the line for a railroad track, it may often happen that a choice may be had between soil or substrata of different kinds, without sacrificing anything in matters pertainrng to right of way, grades or curvature; or the local conditions peculiar to one side of a valley may differ so widely from those of the opposite side, in such respects, for instance, as exposure to wind and drifting snow, slides, falling rocks, surface drainage, springs of water, stream encroachments on the roadbed, the shading of the right of way by steep hills or by forest, as to materially affect the cost of maintenance.
The simplicity of the track structure is the deceptive element in questions relating to maintenance economy, for ideas concerning the stability of track are too frequently confined merely to the question of approved qualities of rails, ties and ballast. To carry traffic, and the machinery of operation, that is, the weight of locomotives and cars, the length, number and speed of trains, will govern the amount of business that the road gets. Certainly the policy of the road should not be to turn away business and reduce weights of trains to fit the track, but on the contrary the track should be made to fit the traffic, since it is the traffic that earns the revenue.
The fact that the track structure lies upon the earth surface, exposed to the extreme action of the natural elements, is a very important consideration in track engineering.
Roadway improvement and protection
The railways realize that their is not a "fair weather" transportation business, but an instrument for uninterrupted servicee to the public and industry. Knowing its impossible to protect every foot orf right of way against the threats of nature as they tranverse mountain, bluff and rivers, the railroads have carried out extensive programs of roadway improvement - cut widening and embankment strengthening. upgrading roadbed, and installing warning devices in the form of slide detector fences, high-water alarms and bridge burnout warning devices.
Roadway construction and maintenance standards
The construction and maintenance departments of every railway have certain standards for material and methods. A railway having an extended mileage has a variety of different kinds of track and many different traffic conditions. Thus the maximum freight-train, the fast freight-train, and the high-speed passenger-train, all with excessively heavy axle loads and total weight, have their own requirements for roadway and roadbed.
The American Railway Engineering Association (AREA) was formed in 1889 to organize a forum for the development and study of recommended
practices for the newly-integrated standard-gauge North American railway
network. In 1905, the AREA issued its first Manual of Recommended Practices. Its initial railway engineering practices were based on the following classification of track on a basis of traffic carried:
Class A Track. All districts of a railway having more than one main track. Also all single-track districts where the traffic equals or exceeds a freight-car mileage of 150,000 per mile per year; or a passenger-car mileage of 10,000 per mile per year and a maximum passenger-train speed of 50 miles per hour.
Class B Track. All single-track districts of a railway where the traffic is less than for Class A and is equal to or exceeds a freight-car mileage of 50,000 per mile per year; or a passenger-car mileage of 5000 per mile per year and a maximum passenger-train speed of 40 miles per hour.
Class C Track. All districts of a railway not meeting the traffic requirements of Classes A or B.
Reference
Walter Mason Camp, Notes on Track
Manual of the American Railway Engineering Association (1921)
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