US2875953A - Railway track construction - Google Patents

Description

March 3, 1959 c. WEBER ET AL RAILWAY TRACK CONSTRUCTION Filed Sept. 21, 1954 FIG.

RNVENTORS.

WEBER TH L. HENSON ATTORNEYS CARL BY KENNE Y thereto the correct gauge spacing apart.

Y crosstie construction 1s United States Patent O 2,875,953 RAILWAY TRACK CONSTRUCTION Carl Weber, New York, N. Y., and Kenneth L. Henson, Rochelle Park, N. J., assignors, by mesne assignments, to Carl Weber, New York, N. Y.

Application September 21, 1954, Serial No. 457,406 4 Claims. (Cl. 238-2) This invention relates to the construction of railway tracks. The invention is characterized by the provision of rail-supporting crosstie slabs, of precast concrete or equivalent imperishable material, which provide more effective support for the rails than is afforded by con-v crossties for the support of the steel rails which are spiked To reduce the rail pressure on the ties, steel plates are inserted under the rails. These steel plates also serve lateral shearing stresses to the spikes.

The crossties rest on a crushed stone or gravel 'ballastA b ed.` The track is stabilized in vertical position by compacting the ballast under the ties. These must be placed some distance apart from each other to permit the use of ballast tampers on both sides of every crosstie. Thus the supporting value of every crosstie is limited to its com pacted surface area, and the rail between ties is subjected to bending stresses. Since the bearing value of the crosstie foundation cannot be increased, it has become necessary to adopt very heavy steel rails to meet the ever increasing demands for heavier and speedier train service.

One of the largest items of cost inrailway operations is for the maintenance of the track. The perishable wooden crossties must frequently be replaced. Water from rain or melting snow penetrates the ballast bed, causing softening of the supporting soil with consequent subsidence of the track. These deficiencies must periodicallybe `corrected to maintain safe traic conditions.

Our new railway track construction eliminates Ythev use of wooden crossties with their tie plates and spikes, andA the disadvantages incident thereto. It also renders the use of stone or gravel ballast superfluous. In accordance with our invention, the railway track comprises a plurality of rail-supporting crosstie slabs, and railssnpported on and secured to said slabs, said slabs having a'length in the direction of the roadbed materially greater than the spacing between them, and thereby providing direct bearing support for the rails over substantially more than fifty percent of their length. Preferably, the slabs have a length in the direction of the track at least three'times greater than the spacing between them so that they provideV direct bearing support for the rails over atleast seventy-five percent of the llength thereof. The roadbed material underlying the slabs is uniformly lcompacted so as to provide a substantially uniform distribution of load bearing capacity over substantially the entire area of each slab. The slabs thus provide maximum support for the rails, and enable rails of given weight to carry greater and faster-moving loads than when conventional wooden employed. The rail-supporting slabs usedin track construction according to the invention are preferably of reinforced of construction of rail-V to equalize the slabs are exemplary only,

ICC

(or prestressed) concrete, and are preferably precast by' mass production methods. Metallic rail fastenings, such as bolts to which rail clips and nuts can be applied, are preferably permanently anchored in the slabs. At least one fill-injection opening preferably is formed in the central portion of each slab, for injecting roadbed fill material under the slabs to insure that the load bearing capacityof the roadbed is uniformly distributed over substantially the entire area of the slab.

These and other features of the invention are described below with reference to the accompanying drawing, in which Fig. 1 is a plan of a railway track constructed in accordance with the invention;

Fig. 2 is a section taken substantially along the line 2-2 of Fig. l; and v Fig. 3 is a section taken substantially along the line 3-3 of Fig. l.

The track shown in the drawings comprises roadbed 5 on which rail-supporting slabs 6 are laid. Rails 7 are laid on and secured to these slabs. The slabs 6 are preferably of precast concrete which advantageously a graded is prestressed or is reinforced with steel reinforcing rods 8..

The width of the slabs, in the direction of the width of the track, is preferably about equal to the width of conventional wooden crossties the case of a standard gauge track). The thickness of the slabs in a vertical direction may also be about the same as conventional wooden ties However, the length of the slabs, in the direction of the length of the track, is substantially greaterthan the corresponding dimension of a wooden crosstie. In the case of the slabs shown in the drawings, their length is approximately equal to the length of two conventional wooden crossties plus the space between them (usually between three and four feet in the case of a standard gauge railway). Slabs of such dimensions are nottoo large to be handled conveniently by railway construction and maintenance crews, and yet are large enough to provide for achieving substantially the f-ull advantages of the invention. However, the foregoing dimensions for the crosstie and the invention is not limited thereto.

Each of the slabs 6 carries rail fastenings by which the rails 7 are secured in place. In the slabs shown, the rail fastenings comprise bolts 9 embedded and anchored in the precast slabs, and rail clips 10 which bear against the rail flanges and are secured in place by nuts 11. However, so far as the invention is concerned, there is nothing critical about the form of the rail fastenings provided.

Each of the slabs 6 is formed with one or more fill# injection openings 12 extending vertically therethrough and located in more or less central areas of the slabs (three such openings are shown in the slabs portrayed in the drawing, but their particular number and location can .be varied over Wide limits, depending on the size between the slabs, it is preferably narrow (generally less than a foot), and does not exceed one third thelength of the slabs themselves, so that the rails mounted on the.` slabs are supported over at least seventy-five percent of their length. ,In any event, .thespace' should .beinarrow enough so that the beam length of unsupported rail be- (for example about eight feet invr (say six to eight inches) as follows: After the roadbed tween the slabs is short andv easily able to.. withstand the bending stresses imposed on it during normal service.

After the rails have been laid on the slabs and fastened inV place, the slabs are raised to. the correct height by pressure injection of roadbed ll material through the holes 12..y The fill is preferably injected at a controlled pressure, so that the roadbed structure underlying the slabs is compacted and the. resultant voids caused by said compaction are filled with the fill material. This injection s continued until a substantially uniform distribution of. load bearing capacity over substantially the entire area of each slab is obtained. The raising of the slabs to theicorrect height and the provision for uniform distribution ofV load-bearing capacity beneath substantially the entire area of each slab cause the slabs to exert a substantially uniform force against the bottom of the overlying rails. The lill material advantageously is cementtious. in character, so that when it has set it forms a consolidated mass and provides for stabilizing the bedV on which the slabs rest. lTo retain the till material in place, the longitudinal sides of the slab are advantageously sealed by tamping with earth, sand, cinders, or the like, and the spaces, if any, between the slabs are advantageously similarly sealed, as indicated at 14.. No other ballast is needed, except perhaps in special cases, as where peculiar drainage requirements exist.

Where existing wooden crosstie tracks are to be reconstructed in accordance with the invention, the existing ballastmaterial may be left in place and may be sealed, after the slabs have been laid thereon, by pressure injection` of cementitious till tration of water below the slabs.

The lill injection holes 12 advantageously are left open, so as to permit later adjustment of the trackif uneven roadbed subsidence or other occurrence ever makes it necessary.

The outstanding advantages of our method of railwayv track construction may be summarized as follows:

The direct support of the rails for much the greater part` of their length by concrete tie slabs, instead of support for less than half their length by spaced wooden crossties,.provides for increased uniformity in the distribu,k

tion of deadv and live loads over the roadbed area. Therefore,4 maximum ground surface pressures of the track structure are 40% of those of conventional wooden crosstie tracks. The concrete tie slabs cover the ground area under them like a waterproof blanket, whereby penetration ofi waterinto the roadbed is minimized and consequent reduction of ground stability by changing moisture content is greatly reduced or may even be made impossible. Theweight ofthe concrete slabs and `their uniform contactwith the roadbed as a result of pressure injection of till materials, are of great importance for oband maintaining superior track stability. Reducedcost of rails (which may be of reduced weight for. given loads and speeds), elimination Iof ballast, tie; andV mass production of the concrete tieV slabs, all contribute to trackconstruction costs` that platesand. spikes,

are favorable by comparison with other methods.

Termites` and harmless. to` concrete crosstie slabs. immune to the deteriorating `effects soilconditions, fungus growths and uences.

Costsv of track maintenance,Y one of the most severe obstacles to profitable railway operation, are reduced lto a mere fraction of present expenditures.

The correctly stabilized track structure with greatly reducedload pressures on. the; supporting ground, protested against intermittentr variations of moisture content,;produeeithe greater'possible safety for trainopera- Wherever subsidence.; of .tracks ontills or adverse soil These slabs. also are of acid or. alkaline other destructiveinmaterial to prevent the pene-A correspondingly reduced,-generally to abouty other insects destructive to Wood arek v conditionsV occurs, corrected at low cost by pressure injection of additional f curing the rails to the slabs along the resulting @rangement is .easily lill material.

The improved rail support provided by the invention leads to longer lifetime of the rails and equipment, and also decreases the cost of operation.

'The greatly increased contact area of the rails on the concrete surface of the supporting tie slabs, and the improved fastening of the rails, minimizes the dangers of rail creeping. y

It is quite evident that these advantages all lead to increased safety and economy in railway construction and operation..

It is of course apparent that the design and construction of our concrete tie slabs are subject to variation to meet specific needs. Ribs or stifeners may be provided where soil conditions or traiic lrequirements must be considered. Special slabs may be furnished for switches, and for rail andv road crossings. Resilient pads of various kindsv may be inserted under the rails to subdue train noises, and other accessories can be incorporated in the track structure to meet the most exacting requirements of every type of railway track construction and service;

In the appended claims the term roadbed is used to designate the ground upon which the railway is to be laid Without rapplication thereto of the usual rock ballast.

We claim: v

l. The method of laying a railway track which comprises leveling the roadbed to line and grade, laying railway supporting cross-tie slabs directly on the established grade so that-the distance between the respective slabs is less than about one half the width of a slab, se-

substantially normal to the lengthwise direction of the space lbetween the slabs, and pressure-injecting roadbed till material beneath the slabs to compact the roadbed beneath them and to till the voids caused by said' cornpaction with the fill material, said pressure-injection beingY continued until the slabs are raised and exert a substantially uniform force against the bottom of Vthe overlying railsV and a substantially uniform distribution of load-,bearing capacity beneath the rails under substantially the entire area of each slab has been obtained.

2. The method-of laying a railway track as set forth in claim 1 in whichA the roadbed lill material is cementitious invcharacter and is injected ata controlled pressure through openings extending through said slabs from ther top to the bottom. v

3. The method of laying a railway track as set forth in claim 2 in which-the roadbed fill materialis confined substantially to the area underlying the slabs until it has set to forma-consolidated, stabilized roadbed mass.

4. lThe method of laying a railway trackas set fort-h inclaim 1 in which the distance between the respective slabs does not exceed more than one third the width of aV slab. Y 4

References Cited in the file of thisv patent UNITED STATES PATENTS Germany v Sept..29,

parallel lines extending,-

Images