Gentlemen, I will attempt to reproduce here something I typed up for the Bridge Line Historical Society Bulletin (the monthly publication of the active group of Delaware & Hudson fans) a few years ago, including a short passage from Trains and a much longer piece prepared by a D&H official in 1938:
A comment about our favorite railroad’s pioneering in the use of welded rail by Steve Wagner in the October 2002 Bulletin prompted member Pat Patrick to send in what follows.
A feature on the most important railroad developments of the Twentieth Century in the January 2000 Trains included a photo of welded rail being unloaded from a freight car with this caption:
WELDED RAIL. The sound of “clickety-clack” might be romantic, but it’s also expensive. Steel wheels pounding on bolted joints of 39-foot track sections wreak havoc on the maintenance-of-way budget. That’s why railroads embraced continuous welded rail, or CWR. First employed by street railways in the 1920’s, it made its debut in heavy-duty trunkline service in 1937 along a 30-mile section of Delaware & Hudson in upstate New York. CWR paid immediate dividends, cutting maintenance costs even as it smoothed out the ride. The technology took off in the 1970’s to the point where, today, railroads proudly report that 104,000 miles of track are CWR.
And Railway & Locomotive Historical Society Bulletin No. 49 (1939) contained the following article. [Some punctuation has been changed in the interest of clarity, but unusual spellings have been left alone. For instance, what today is called thermite is referred to as Thermit.]
Continuous Rail
Illustrated lecture by H.S. Clarke, Engineer, Maintenance of Way, Delaware & Hudson Railroad, before the New York Chapter of the RAILWAY AND LOCOMOTIVE HISTORICAL SOCIETY in the Engineering Societies Building, 29 West 39th Street, New York, on Nov. 12, 1938.
Few of us realize how true it is that a railroad is never completed. Spectacular fast trains, mighty locomotives, and air conditioning are only steps in a process of improvement that is continually going forward.
So, with permanent way, it is necessary, in order to meet these ever increasing demands for higher speeds and heavier loads, under which the cost of track maintenance must rise, to devise more comprehensive measures of track construction and maintenance methods than those which we all used in the late past. Such improvements to the standard of track construction must be radical and far reaching.
There is an old axiom that one must spend money to save money, just as one must spend money to make money, and the railroads have been looking around for the places to spend money to save money. On the Delaware and Hudson Railroad, we have been singularly fortunate in having a management who recognized this trend for some years, and have provided us with every opportunity and backing to develop a track structure and maintenance methods to meet these conditions.
With labor the largest item in railroad maintenance, there are opportunities for spending money to save labor, reducing maintenance costs, not necessarily during the current year, but of large importance in the long run, over a period of years.
Like most railroads, we have been carrying on a program of improved drainage, ballasting with ballast of suitable type and to an adequate depth, installing hardwood creosoted ties and heavy rail, and we have continued to carry on these programmes on a somewhat reduced scale throughout the depression. With the exception of steel ties, most railroads have been using these means to modernize their permanent way.
The steel tie used on the Delaware and Hudson Railroad is made by welding a standard tie plate on two eight-foot lengths of scrap rail, the welding being done with an automatic electric welding machine developed by the General Electric Company. We have, at present, some 165,000 of these ties in yards, sidings and, to some extent, on branch lines, their use being limited to where we have no signal circuits.
However, to meet the problem of better track, which may be more economically maintained, these steps, it was thought, would not be sufficient.
By preventing decay, the creosoting of ties lengthens their life; however, the treatment is expensive and, to obtain full advantage of the investment, the tie must be protected against mechanical wear and spike killing. The rail joint is universally recognized as the weakest point in the track and it is recognized that over 45 per cent of track labor is now necessary in order to keep the joint in proper line and surface. More rails are renewed yearly and have their service life shortened by reason of battered and chipped ends than for any other cause, thus providing a major problem.
Here were two problems well worth considering.
To meet the first condition, a heavy double-shouldered tie plate was developed, canted and crowned, fastened to the tie by means of a compression screw spike, independent of the rail fastenings. Thus the tie plate became, in effect, a part of the tie and prevented mechanical wear of the tie.
It also was held necessary to get rid of the old destructive track spike and its spike-killing effect on the tie; therefore, it was felt necessary to develop a fastener to fasten the rail to the tie plate independently of the screw spike holding the tie plate to the tie and, at the same time, eliminate the inefficient anti-creepers generally in use.
Such fastenings must met certain conditions:
They must stand being strongly tightened and remain thus in order to prevent the rails from creeping on the ties. They must have some elasticity in order to dampen the effect of the stresses developed in the track and the movement of the tie in the ballast resulting from impact. It must be possible, at any time, even after a number of years, further to tighten the fastening to take up wear or renew part or all of the component parts. Could such a fastening be developed that would be effective instantly it was applied to resist the movement of rail longitudinally in either direction against movement from creeping, and also prevent the rail expanding or contracting?
After many experiments with various types of clip fastenings, the spring clip fastening now used on the Delaware and Hudson Railroad was adopted and used with the double-shouldered plate previously described, punched to take the fastening.
With these fastenings, the rail is held by means of two spring steel clips, bolted to the tie plate at the center of the crown and bearing on the base of the rail. Since the rail-to-tie-plate fastenings are independent of the tie-plate-to-tie fastenings, each group is free to perform only the work it is designed to do, while the rail, the tie plate and the tie are co-ordinated into one strong but elastic and flexible unit.
The fastening of the rail to the tie plate and through that to the tie by means of the spring steel clips greatly strengthens the track structure, leaves it sufficiently elastic to absorb the impacts and loads applied to it and greatly decreases the vertical motion of the rail and of the tie over that of the standard track, although the normal wave motion of the rail is permitted to pass freely.
The decreasing of this vertical motion means a lessened pounding on the tamped ballast beneath the tie. It is this incessant pounding or pumping of the tie that breaks down the interlocked ballast, and causes the track to go out of line and surface.
Spring-clip constructed track stays in line and surface for longer periods than standard track, and the relative motion of the rail and tie remains substantially the same in all tests, which is extremely indicative of the uniformity of this type of track structure. The pressure exerted by the spring clip permits the free wave motion of the rail, but does not permit it to progress longitudinally. So well is the rail restrained that changes in length due to expansion and contraction are prevented. It was this feature of spring clip construction, combined with several other facts that led to the belief that it was possible and practical to weld rails into long lengths, lengths limited only by the necessity for insulated joints for signal circuits, and location of switches and crossovers.
There are two distinct factors which must be taken care of in standard track: one is the creeping of track, and the other is expansion or contraction of the rails due to temperature changes. Combined, there are many indications that these factors cause large temperature stresses in a great mileage of standard track and sometimes result in what is known as “sun kinks.”
The tendency to movement by creeping is caused by the running of trains. When the movement takes place, it usually extends over comparatively long stretches of track. The principal cause is the wave motion of the rail which is set up by the moving train. There is usually a slight upward and then a downward motion of the rail and ties just preceding a moving locomotive or train, owing to the flexibility of the rail.
The ground below also springs for quite a depth underneath the track and for some distance each side, so that there results a wave motion in the rail of much greater amplitude than at first appears. In thirty-nine foot rails or other short lengths, the propagation of the undulating wave motion is, more or less, arrested at every joint, causing each length of rail to move ahead. Hence running or creeping of rail takes place successively by rail lengths, one rail at a time; or, at most, by a few lengths acting together as one. With continuous rail, there are no joints to interrupt the wave motion of the rail; therefore, the tendency for rail to creep or run is eliminated.
Experiments conducted some years ago with a five-hundred-foot length of rail developed that, over a range of temperature changes between minus 20 degrees Fahrenheit and plus 20 degrees Fahrenheit, the length of the rail was unchangeable as between these limits, and no movement was observed, but above 20 degrees Fahrenheit, the rail was quite sensitive to temperature changes.
Where rail is so fixed that it cannot expand into an extended position when heated and cannot move in any other way, as, for instance, by buckling, it must remain unaltered in size since the external forces holding it are greater than the compressive stress set up by the temperature rise. Alternatively, if rail cools below the temperature at which it is fixed, a tensile stress is created to be resisted by the influence that fixes the rail; that is, the rail is compelled to undergo the stresses set up by expansion of the metal without lengthwise extension and vice versa.
These stresses are so far below the elastic limit of the rail itself that thy can have no effect upon it and, therefore, are of no consideration in connection with the subject of continuous rail other than representing a force that tends to lengthen or shorten the rail.
Summarizing, we reach the following conclusions:
(1) In long rails, the weight of the rail, in itself, reduces the theoretical amount of
expansion or contraction of a rail.
(2) The double-shouldered tie plate has a tendency to bind the rail and further to
decrease the amount of expansion or contraction.
(3) The holding power of the spring clips against longitudinal movement in either
direction combined with the above facts out-balances the forces of expansion and contraction, so that there is no lengthwise movement, except a slight movement at the end rails, not much more than would be expected in 39-foot rails.
(4) In continuous rail, rail creepage does not enter into the problem, as it does not
exist to any appreciable extent.
(5) The ranges of temperature changes that actually affect changes in the length of
rail are not the total temperatures of the climate in question, but only from approximately plus 20 degrees Fahrenheit to plus 130 degrees Fahrenheit, or the hottest day that may be encountered.
(6) In heavy rock ballast, little attention has to be given the temperature at which
the rail is fixed, as it can be fixed within a range of, say, 65 degrees Fahrenheit to 90 degrees Fahrenheit without fear.
(7) In cinder or gravel ballast, which is lighter and has less holding power than rock ballast, the rail should b fixed within a range of say, from plus 80 degrees Fahrenheit to 95 degrees Fahrenheit.
(8) In ordinary track, there are numerous cases of sun kinks, due generally to poorly anchored track which has been creeping and closed the expansion gaps.
(9) Sun kinks in ordinary track always result from causes which easily may be determined and corrected.
(10) There should be far less fear of sun kinks in continuous than in ordinary track, as creepage does not enter the problem and the cause of sun kink is better controlled, may be noted and corrected quickly.
These facts were tested out in continuous rail laid in Albany in 1933, the longest rail being 2,750 feet; this rail has been in service four years without giving us any trouble. Further installations were made at Mechanicsville [sic – SW] in 1934, at Schenectady and Windsor in 1935, and at Comstock and Cohoes in 1936 and 1937; this year, all new rail laid was being welded. At the end of this year, we had 450,000 lineal feet of welded rail in service, or approximately forty-five track miles of continuous track.
This introduction of continuous rail brought up an important and exact condition that had to be met: namely, a sound, high-quality weld. Extensive studies and research were carried out, relative to the many phases of welding theory and practice, in both Europe and [the] United States of America. Exhaustive tests were made under different procedures, with the co-operation of expert consultants, and have resulted in the development of satisfactory welds.
Test welds have been subjected continuously, day and night, to severe rolling load fatigue tests, following a similar procedure of the extensive rail investigations by the University of Illinois and considered the nearest approach to actual service conditions in track. Many other well-known rail tests were also made.
THERMIT PRESSURE WELD PROCESS:
The Thermit pressure weld is made by casting a steel collar around the base and web of the rail and then forcing the rail ends together, making a pressure weld in the head of the rail. This is accomplished by using a material known as Thermit. This material consists of powdered aluminum and iron oxide. At a high temperature, the aluminum unites with the oxygen in the iron oxide and there results aluminum oxide slag and free iron. In making a weld, this reaction is started with ignition powder, and in about twenty seconds the reaction is complete and the temperature has been raised to about 5,000 degrees Fahrenheit.
At this time, the molten mass is poured into molds previously clamped around the rail ends. The steel or iron, being heavier than the aluminum oxide slag, flows in first and unites with the base and web of the rail ends while the aluminum oxide slag lies in the mold around the head of the rail and raises the temperature of the head to a welding temperature in three minutes, when the rail ends are forced together with clamps, making the pressure weld.
ELECTRIC FLASH WELDING:
The rail ends are clamped in the welding machine, one in fixed position and one movable. Current clamps are connected to a low volt transformer. Short circuiting between the two faces preheats the rail ends. No preparation of faces other than cleaning or flux is needed. Continuous short circuiting burns off the high spots on the faces and builds up a pressure of gases between the rail ends. Air cannot gain access to the faces. There is, therefore, no oxidation of the faces, which remain chemically clean. About two minutes after the application of current, the faces are brought together under proper pressure. All molten metal is squeezed out and the weld is made. After the rail has been removed from the welder, it is slow-cooled or normalized in an oil furnace and then passes on to the grinders, where the excess metal squeezed out by the welding pressure is removed and the head of the rail properly surfaced.
On the Delaware and Hudson Railroad, it has been our practice to do the welding by either the Thermit or flash method on cars in the yard, welding the rail into 800 to 1500 foot lengths and then, when twelve strings have been completed, to haul the train load out and unload it where it is to be installed.
Continuous track has many advantages over track laid with the standard length rails, some of these being as follows:
(1) Joint maintenance is eliminated, including maintenance of bolts and angle bars, surfacing and lining.
(2) Rail life increased, joint batter ended, less frequent rail laying.
(3) Rail creepage eliminated.
(4) Deterioration of the joint ties eliminated and not necessary to space ties.
(5) Elimination or replacement of joint bars and reconditioning rail ends.
(6) Smoother riding for passengers.
(7) Rolling stock maintenance reduced; no shock at joints.
(8) Signal circuit bonding eliminated.
(9) Less tractive power is required to haul trains over jointless track.
It will be of interest to you to know that on one railroad using electric trains, the “nosing” of the trains has been very serious. In most cases where they had this “nosing” trouble, it would start immediately when the rail was renewed, and, in a very short time, there were indications of the rail being very badly cut. An installation of a mile of continuous track with spring clip construction, put in open track about a year ago, thus far does not indicate the slightest sign of “nosing” or damage to the rail from this cause.
It is also of interest to note that there have been several installations of continuous rail on other roads, both in the open and in tunnels, and it appears that in the next year there will be many more.
I had the pleasure of conducting an English engineer over our installations, and he advised me that in the London Tubes, which are much smaller in size than those in New York, the contour of the tube giving little clearance outside the cars, the noise was so great, it was impossible to talk to a person sitting beside you without shouting. In an endeavor to overcome this, they laid some test stretches of welded track and, in addition, placed some sound insulation around the lower sides of the tube, resulting in an eighty percent reduction in the noise.
Apparently there are many advantages of welded or continuous rail that, as yet, we have not realized, and more installations, under various conditions, will bring these out.
While it is a little early to make any reasonably accurate estimate of the reduction in maintenance expenditures resulting from continuous rail and spring clip construction, there is already obvious a substantial saving. We have track of this type, put up several years or more ago, over which there is a fairly heavy traffic, on which there has since been no work and which is in as good line and surface as when originally put up. This track gives every indication of staying in good line and surface for many more years with little, if any, attention. Railroad men who have been studying continuous rail feel that this development opens up the possibility of securing far stronger, safer and better riding track with a reduction in future maintenance expenditures of 50% or more, plus a now unascertainable saving in maintenance of rolling stock.
[Three photographs accompanied the article. “A stretch of Main Line on the D. & H.” shows an immaculate stretch of straight double track with light-colored ballast in a rural area. “Carrying the continuous rail to place of installation” is an interior view of wood gondolas with their ends lowered (or perhaps flatcars with wood sideboards) loaded with five lengths of welded rail. “Close-up of a Thermit Pressure Weld” seems to show a very conspicuous buildup of metal below the top of the welded rails.]