Laminated wooden railroad crossite having exposed end-grain forming part of the load bearing surface

A laminated wooden load support structure is described herein, wherein at least one of the lamina is comprised of a plurality of wooden elements orientated with respect to the load bearing surface or wear surface such that the end-grains of the wood elements of the lamina form a part of the load bearing surface.

BACKGROUND OF THE INVENTION 
This invention relates to railroad crossties, more particularly, to 
laminated wooden railroad crossties. 
In the conventional construction of railroad wooden crossties, a tie plate 
carrying a rail is disposed upon the surface of the wooden tie. As a train 
passes over a crosstie, a load is imparted to the crosstie through the 
rail and tie plate. The tie plate spreads and distributes the load to the 
crosstie surface beneath the tie plate. The area of the tie beneath the 
tie plate is commonly referred to as the wear area because this is the 
area that tends to disintegrate sooner than do the other areas of the tie. 
Conventionally, spikes are driven through holes that are disposed near the 
lateral edge of the tie plate and lodged in the crosstie. These spikes 
secure the rail to the tie plate and likewise secure the tie plate to the 
wooden tie to restrict horizontal and vertical movement of the rail as a 
train passes over the rails. 
Customarily, each of the two rails of a railroad track are canted inwardly 
by the tie plate being disposed at a slope of one unit of rise to forty 
units of run, to improve the load bearing qualities and to help maintain 
the gauge (distance between the rails) of the rails, particularly when a 
train passes. Actually, the spikes primarily hold the gauge. Because each 
rail is canted inwardly of the track, the passing of train wheels over the 
track tends to cause slight amount of horizontal movement to occur in 
conjunction with a slight amount of vertical movement of the rail. This 
combination of vertical and horizontal motion tends to effect a rocking 
movement of the tie plate and tie, which movement in turn causes an 
indentation in the tie; a phenomena known in the railroad industry as tie 
or plate cutting, i.e., the cutting or wearing of the wooden tie in the 
tie wear area. This plate cutting is accelerated by a number of factors. 
For instance, moisture under the tie plate softens the wood fibers of the 
wear area. Dust and abrasive particles from the road bed become trapped 
under the tie plate; consequently, the rocking movement of the plate under 
the load and vibration of passing trains literally grinds the abrasive 
particles under the tie plate into the tie, destroying the supporting 
characteristics of the wood fibers of the tie in the wear area. Because of 
this wearing or plate cutting, ties must be replaced often. 
Hardwoods such as red and white oaks, tupelo, sweetgum, and beech have been 
the most popular type of wood for employment in construction of railroad 
ties because of hardwood's superior wear characteristics. However, one 
particularly favored type of hardwood used to construct crossties is oak. 
However, the available supply of hardwood fluctuates. Unexpected forest 
fires and droughts can deplete available supplies of hardwood and supplies 
of hardwood are not easily replenished due to the extended growth cycle of 
hardwood. In addition, hardwood is increasingly being diverted to other 
product areas. Parenthetically, it should be noted that the construction 
of conventional crossties results in a high percentage of wasted wood. 
Laminated wooden crossties have been proposed to allow more efficient 
utilization of available supplies of wood. Laminated crossties are created 
by laminating individual lamina to form a crosstie. The conventional 
laminated crosstie is constructed such that each lamina is a unitary 
wooden element laminated to have generally their grains parallel to one 
another. The lamina are bonded together, and usually chemically treated to 
arrest decay and insect attack. 
The laminated wooden crosstie has exhibited field performance comparable to 
conventional unitary crossties. However, laminated wooden crossties have a 
purchase price much higher than that of conventional crossties. Attempts 
to lessen the financial impact of laminated ties has centered on 
improvement in the load capacity and wear characteristics of laminated 
ties. Improved crosstie load capability enables one to deploy fewer 
crossties, and improved wear characteristics results in a longer crosstie 
useful life. Efforts to increase the load and wear characteristics of 
laminated crossties have involved such suggestions as impregnating the 
crosstie with a plastic resin and using wooden inserts beneath the tie 
plate implanted in the crosstie. These suggestions to increase the load 
and wear characteristic of laminated crossties has met with limited 
success. 
The present invention offers more efficient utilization of wood material. 
The present invention also offers superior wear resistance and load 
bearing capacity for crossties. The invention allows one to deploy less 
expensive and more plentiful softwood without appreciable degradation of 
crosstie performance. The invention further allows one to design a 
crosstie which best compliments the type of rail traffic expected to be 
encountered, e.g., lightweight intracity commuter rails can employ ties 
with a minimum of hardwood, resulting in less material costs and still 
derive the performance advantages of the present invention. 
SUMMARY OF THE INVENTION 
A laminated wooden railroad crosstie consisting of at least one lamina 
including a plurality of generally rectangular wooden elements in the wear 
area of the tie, which elements are oriented within the crosstie such that 
their end-grains are exposed, forming part of the wear surface. The type 
of wood used to construct the crosstie may be either of the hardwood 
variety or the less expensive softwood variety, or a combination of hard 
and softwood. Because of the presence of the wood elements, which are 
relatively small, less wood is wasted.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
A tree is an anatomically complex structure, being comprised of structural 
elements which are, in the main, long pointed cells known as fibers which 
vary in length within a tree and among the species of the trees, but 
generally range from one millimeter to about eight millimeters in length, 
and are firmly grown together. The cells that are immediately under the 
bark of the tree and that take an active part in the life process of the 
tree are called "sapwood". The inner sapwood cells that have become 
inactive are called heartwood. Each year a tree produces a well-marked 
growth ring of the sapwood. These growth rings are generally visible as 
the tree is cut transversely to its length. 
In cutting a tree into lumber or into ties, a tree is generally cut so as 
to produce one or more pieces of lumber. The surface of the lumber which 
shows those fibers that have extended longitudinally of the length of the 
tree which became the lumber or tie is referred to as showing 
"side-grain". When the surface was cut at right angles to the longitudinal 
axis of the tree, it is generally possible to distinguish some arc of the 
circle or growth ring of the tree, and this is referred to as showing the 
"end-grain". Those familiar with lumber can readily distinguish between 
the "end-grain" and the "side-grain" of the lumber. 
The tie of this invention is composed of wooden elements 1, FIG. 1, whose 
length, width and height are respectively indicated as l, w, and h. 
The faces 2 of element 1 have grains 5 extending longitudinally along the 
faces 2. The sides 4 also have side-grains 6 extending longitudinally 
along the sides 4. The ends 3 have end-grains 7 which, as viewed in FIG. 
1, have generally arched extension. The grains 5, 6 and 7 shown in FIG. 1 
are a result of the growth characteristics of trees. The hereafter 
referred to stubs conform to element 1, however, have a relatively short 
length. One reasonably skilled in the art of cutting timber will know the 
proper procedure for cutting timber to derive an element generally 
conforming to element 1. 
The cross-grain railroad crosstie 11, FIG. 2, is comprised of laminae 13, 
15, 17, 19 and 21, each lamina having the same overall dimensions. Laminae 
13, 17 and 21 are unitary wooden elements, each being so oriented that the 
side-grains 29 form a part of the load bearing surface 12. Laminae 13 and 
21 form outer layers and lamina 17 forms an inner layer. 
Laminae 15 and 19 are each comprised of a series of wooden stubs 23 and 25 
that have a length corresponding to the width of the other laminae 13, 17 
and 21. Stubs 23 and 25 are aligned with respect to one another within 
each lamina so that the sides of adjacent stubs 23 or 25 are in contact 
with one another. Each stub 23 or 25 has its end-grains 27 forming a part 
of the bearing surface 12. 
The stubs 23 which form lamina 15 are not bonded to each other as is also 
the case with stubs 25 which form lamina 19. Stubs 23 and 25 can be 
adhesive bonded together but to do so would increase cost and may 
substantially lower the bending capability of a tie. In the preferred 
embodiment, stubs 23 and 25 are not bonded to each other but are bonded to 
adjacent lamina 13, 17 or 21. 
The laminae 13, 15, 17, 19 and 21 are bonded together with a bonding agent 
or adhesive placed between adjacent laminae 13, 15, 17, 19 and 21. 
To ascertain the wear characteristic of a softwood tie made in accordance 
with this invention, a partial tie A (the tie length A was less than an 
actual tie) was constructed and tested. Tie A was composed of softwood 
(southern yellow pine) in accordance with the aforedescribed tie 11, FIG. 
2. The bonding agent was phenol-resorcinol-formaldehyde adhesive (sold 
under the trademark Penacolite) which was employed in all herein described 
softwood test ties. Laminae 13, 17, and 21 of tie A were 1 inch thick (x) 
and laminae 15 and 19 were 2 inches thick. Tie A was fitted with a 7-inch 
by 14-inch steel tie plate and a piece of 132 pound rail and tested for 
2.38 million cycles in an Association of American Railroad Tie Wear 
Machine (TWM) which subjects a specimen to a load condition comparable to 
that on the outer rail of a sharp curve as determined from field 
investigation. A load condition comprised of a vertical load component 
averaging 20,000 pounds with horizontal components of 7,500 pounds 
outwardly and 3,750 pounds inwardly directed was applied at a rate of 129 
cycles per minute for roughly 2,500,000 cycles or 5,000,000 application of 
loads with full release between applications. The load cycles simulate the 
load condition in which a tie in normal use is subjected to in 10 to 15 
years. At the end of the test, the average indentation in the tie plate 
area or wear area of the tie A was 0.04 to 0.05 inch. These results 
compare favorably with similar previous tests performed on a solid oak tie 
tested at 2.5 million cycles which displayed indentations of 0.05 to 0.15 
inch after testing. 
The hereinafter described alternative preferred embodiments are made 
entirely of wooden elements generally conforming to element 1, shown in 
FIG. 1. 
A second embodiment of a cross-grain crosstie of this invention, crosstie 
51, FIG. 4, is comprised of a plurality of laminae 53, 54, 55, 56 and 57, 
respectively, each lamina having the same overall dimensions. Laminae 53 
and 57 are unitary wooden elements placed with their respective side 
surfaces 4 to form part of the load bearing surface 52. Laminae 54, 55 and 
56 are each comprised of a plurality of wooden stubs 58 and an element 59. 
Each lamina 54, 55 and 56 has a plurality of stubs 58 at the longitudinal 
extremes separated by an element 59. Stubs 58 have their corresponding 
surface 3 forming part of the load bearing surface 52. Element 59 has 
either the corresponding surface 2 or 4 forming part of the load bearing 
surface 52. The stubs 58 are positioned longitudinally along the tie 51 to 
receive any applied load. The laminae 53, 54, 55, 56 and 57 are bonded 
together, the bonding agent being placed between adjacent laminae. The 
stubs 58 are aligned within laminae 54, 55 and 56 such that the sides of 
adjacent stubs 58 are in contact. 
A second embodiment cross-grain crosstie 61, FIG. 5, is shown. Crosstie 61 
is comprised of a plurality of laminae 63, 65 and 67, respectively. 
Laminae 63 and 67 are unitary wooden elements oriented to have their 
respective side surface 4 forming part of the load bearing surface 62. 
Laminae 63 and 67 have the same general overall dimensions. Lamina 65 is 
comprised of a plurality of wooden stubs 69. Stubs 69 have their 
corresponding surface 3 forming part of the load bearing surface 62. 
Unlike the aforedescribed and hereinafter described crossties, stubs 69 
are aligned within lamina 65 such that their face surface 2 of adjacent 
stubs 69 contact and the side surface 4 of stubs 69 contact surface 2 of 
laminae 63 and 67. The laminae 63, 65 and 67 are bonded together, the 
bonding agent being placed between adjacent laminae 63, 65 and 67. 
Cross-grain crosstie 81, FIG. 6, is comprised of a plurality of laminae 83, 
85, 87, 89 and 91, respectively, of the same overall dimensions. Laminae 
83 and 91 are unitary wooden elements placed with their respective side 
surface 4 forming part of the load bearing surface 82. Laminae 85, 87 and 
89 are each comprised of a plurality of wooden stubs 93. Stubs 93 have 
their corresponding surface 3 forming part of the load bearing surface. 
Stubs 93 are aligned within each lamina 85, 87, 89 such that their 
corresponding side 4 is in contact with adjacent stubs 93. The stubs 93 
are not aligned across tie 81 to facilitate a greater resistance to a 
transverse directed load. A bonding agent is placed between adjacent 
laminae 83, 85, 87, 89 and 91. 
Cross-grain crosstie 101, FIG. 7, is comprised of a plurality of laminae 
103, 105, 107, 109 and 111, respectively, of the same overall dimensions. 
Laminae 103, 107 and 111 are unitary wooden elements placed with their 
respective side surface 4 forming part of the load bearing surface 102. 
Laminae 105 and 109 are each comprised of a plurality of stubs 113. Stubs 
113 have their corresponding surface 3 forming part of the load bearing 
surface 102. Stubs 113 are aligned within laminae 103, 107 and 111 such 
that their corresponding side 4 is in contact with adjacent stubs 113. A 
bonding agent is placed between adjacent laminae. Tie 101 is unlike tie 11 
(refer to FIG. 2) in that the stubs 113 of lamina 105 are not aligned to 
stubs 113 of lamina 109. 
To further realize the potential of the present invention, aforedescribed 
tie A was subjected to three cycle vacuum pressure delamination tests, 
performed as specified by the American Society for Testing and Materials 
(ASTM-D2559-72). Total delamination was less than 1 percent. Such limited 
delamination indicates that the cross-grain construction is sufficient to 
offset the stress generated by the anisotropic properties of wood. 
A partial tie B was constructed of red oak laminae 13/4 inches in thickness 
in conformity with the aforedescribed tie 11 and tested in the TWM in 
accordance with the procedure for tie A, except that after 2,500 cycles, 
the tie plate was covered with sand, and water was sprayed on the tie 
surface several times a day to increase the plate cutting action. The 
bonding agent was resorcinol-formaldehyde adhesive (sold under the 
trademark Penacolite) which was employed in all herein described hardwood 
test ties. At 1.3 million cycles, the tie was cooled in a dry ice bath 
(saturated calcium chloride) for a day to approximately -40.degree. F. 
while testing cycles continued. At 1.8 million cycles the tie was heated 
with lamps for 16 hours to approximately 170.degree. F., the temperature 
cycle briefly simulating rather extreme climate conditions. After 2.52 
million cycles the tie B was removed from the tie wear machine. The tie B 
displayed only slight indentation occurring; the maximum indentation was 
0.027 inch and the average of 21 measurements in the tie plate area was 
0.018 inch. 
A partial tie C, identical to tie B, was treated with a preservative 
comprising 60 percent by weight of a creosote. The main constituents of 
creosote have been classified by W. P. K. Findlay in "Preservation of 
Timber", Adams and Charles Black, London, 1962 as: (1) tar acids such as 
phenol, creosol, and xylenol, etc., and (2) tar bases such as pyridine, 
quinoline and acridine, and (3) neutral oils such as a mixture of 
naphthalene, anthracene and other neutral hydrocarbons. 
The retention of creosote within the tie stub was higher than normal (11.2 
pcf vs. approximately 7 pcf) due to the short vertical stubs 23 and 25 
being thoroughly impregnated. Since the indentation of tie B was so 
slight, tie C was tested without a tie plate beneath the fitted 132 pound 
rail and a cant was created in the wood of a 1 unit rise to 40 unit rise. 
During the wear test, severe rocking motion of the rail base against the 
tie wearing surface developed due to the inability to construct the 
perfect cant. Sand and water were added and the temperature was cycled 
(-40.degree. F. to 140.degree. F.) during the wear test as was done to tie 
B. At approximately 1 million cycles the cant was lost and the rail rocked 
severely for the remainder of the test. When the test was concluded at 
2.55 million cycles, the wear to tie C was at an average indentation of 
0.046 inch with a maximum indentation of 0.114. Solid oak ties subjected 
to comparable test would be expected to display average indentations of 
0.25 to 0.50 inch. As observed, the partial ties conforming to the 
aforedescribed tie 11 composed of hardwood exhibited marked superior wear 
characteristics to conventional unitary hardwood ties. The moisture 
content of tie C prior to the test was 8 percent. At the conclusion of the 
test the moisture content of tie C increased from 8 to 10 percent without 
any apparent effect on the strength to tie C. 
A partial tie D, cut off from tie B, and a partial tie E, cut off from the 
creosote tie C, were subjected to standard compression shear and cycle 
vacuum pressure delamination tests (ASTM: D2559-72). The cross-grain 
construction will give rolling shear values which, in softwood, are 
roughly 1/4 of the strength of parallel-grain shear results. The partial 
tie D had shear values of 1,305 psi with 54 percent wood failure. The 
partial tie E had shear values of 1,144 psi with 64 percent wood failure. 
The delamination test showed 1.1 percent after the third cycling which 
further indicated treatment had no deleterious effects on bond 
performance. Although the wood was observed to have checked (relatively 
small splits) and distorted some in contour, no large glue line failure 
was observed. For both partial ties B and C the thermal heat generated 
during the tie wear test was less than 2.degree.-3.degree. F. deviation 
from ambient conditions. If any delamination would have occurred, heat 
generated due to friction of the laminae rubbing against each other would 
have raised the internal temperature considerably. 
Theoretically, the passage of a train over a crosstie causes the supporting 
crossties to bend, assuming an arched configuration with respect to the 
track bed. In order to assess the bending strength of the cross-grain tie, 
standard bending tests were performed on ties made from southern yellow 
pine. A crosstie F according to the embodiment 31 was constructed to have 
a bearing surface 32 comprised entirely of stubs 43 end surface. Tie 31 
was comprised of laminae 33, 35, 37, 39 and 41, respectively, each lamina 
33, 35, 37, 39 and 41 being comprised entirely of stubs 43 (refer to FIG. 
3). The stubs 43 of a particular laminae 33, 35, 37, 39 and 41 are aligned 
within a lamina such that the sides 4 of adjacent stubs 43 are in contact. 
To obtain maximum exposure of end-grain 45, it was decided to set the end 
grains 45 of the individual laminae 33, 35, 37, 39 and 41 at a bias angle 
"2a" relative to end-grains 45 of adjacent laminae 33, 35, 37, 39 or 41, 
the end-grain 45 of stubs 43 of a particular laminae 33, 35, 37, 39 or 41 
being generally parallel. The end-grains 45 are raised through angle "a" 
from the horizontal. The laminae 33, 35, 37, 39 and 41 were laminated 
together such that laminae 33, 37 and 41 have their end-grains 45 raised 
and directed to the left, as viewed in FIG. 3, and laminae 35 and 39 have 
their end-grains raised and directed to the right, as viewed in FIG. 3. A 
bonding agent, phenol-resorcinol-formaldehyde, was placed between adjacent 
laminae 33, 35, 37, 39 or 41. Three crossties G, H, K, in conformity to 
tie 31, were made having respective angles "a" of 30.degree., 45.degree. 
and 60.degree.. These three ties and two other tie configurations of a 
conventional crosstie L, a cross-grain crosstie M, FIG. 2, and a crosstie 
N laminated in the conventional manner with the faces (2) of the laminae 
having the bonding agent and bearing the load. All crossties were 
2".times.2".times.28" which served as a reasonable one-fourth model and 
each crosstie was comprised of five laminae. Each lamina was approximately 
0.4 inch thick. The results from the static bend test are shown in Table 
I. 
TABLE I 
______________________________________ 
STATIC BENDING TEST RESULTS 
MOE, 
TIE CONFIGURATION MOR, PSI.sup.a 
PSI.sup.a (.times. 10.sup.6) 
______________________________________ 
(1) Bias Grain Laminated Tie 
Nominal Actual 
30.degree. 
29.degree. 3,882 0.535 
45.degree. 
46.degree. 2,110 0.243 
60.degree. 
59.degree. 1,470 0.167 
(2) Cross-Grain Laminated Tie 
8,694 1.112 
(3) Conventional Laminated Tie 
14,405 1.650 
(4) Unitary SYP.sup.b Tie 
(12,800) (1.74) 
______________________________________ 
.sup.a Average of three samples. 
.sup.b Average of literature valves for the four species that account for 
approximately 90% of SYP (southern yellow pine) group. 
The static bending test results are expressed in the form of moduli of 
rupture (MOR) and elasticity (MOE) in Table I. (The lower the MOR, the 
lower the material strength; the lower the MOE, the greater the elasticity 
of a material.) The bend test results indicate that the bias grain 
laminated tie had substantially lower MOR and MOE when compared to a 
conventional unitary tie. 
It is generally conceded that conventional laminated ties are stronger than 
corresponding unitary ties, due to the wood imperfection of the various 
laminae being randomly spaced as contrasted with unitary wood ties wherein 
imperfections are centered in a particular tie region. It is concluded 
that the MOR values indicated in Table I for the cross-grain conventional 
laminates are substantially lower than their actual values. The 
discrepancy between the test value and actual value of the MOR is believed 
to be due to the fact that one of the outer laminae was substantially 
thinner (0.3") than the remaining laminae (0.4"), during testing, the thin 
laminae rupturing prematurely. Noting that during bending, a specimen's 
upper and lower surfaces are subjected to tensile or compression loads, 
and that the outer laminae have a primary influence on the tensile 
strength, the early rupture of the thin outer lamina is felt to have 
significantly lowered the test results. Therefore, had it not been for the 
early rupture of the thin outer lamina the MOR for the cross-grain tie 
would have been substantially higher, indicating more than adequate 
bending strength. 
The results of the aforedescribed test demonstrates the marked superior 
overall performance characteristics of a cross-grain laminated crosstie as 
compared to conventional unitary crossties made from comparable wood. The 
number of laminae or order of laminae is not material to the performance 
of a cross-grain tie, provided there is sufficient end-grain exposure to 
applied tie loads. Sufficient end-grain exposure is a matter of judgement 
based on anticipated load condition and tie material. 
As earlier stated, the superior wear performance of cross-grain ties is 
primarily attributed to the presence of end-grains comprising part of the 
wear surface. Therefore, increased end-grain exposure is advantageous to 
tie wear performance. Referring to FIGS. 4, 5, 6 and 7, it is observed 
that the end-grains 60, 71, 95 and 115 extend generally diagonally across 
the respective stubs 58, 69, 93 and 113 to increase grain exposure. The 
relative direction of end-grains 60, 71, 95 and 115 within their 
respective stubs 58, 69, 93 and 113 to other stubs 58, 69, 93 and 113 is a 
matter of choice. It is noted that the aforedescribed cross-grain 
crossties 11, 51, 61, 81, 101 will perform comparably as well if their 
respective laminae (13, 17, 21), (53, 57), (63, 67), (83, 91) and (103, 
107, 111), which laminae have their side surface, corresponding surface 4 
of element 1, forming part of the load bearing surface 12, 52, 62, 82, or 
102, were reorientated such that the laminae face surface, corresponding 
surface 2 of element 1, formed part of the load bearing surface 12, 52, 
62, 82, or 102.