113 
To which may be added that : 
(1) The average life of good steel ties is considerably longer than that 
Of best wooden ties (estimated at 30 to 50 years).* 
(2] The width of gauge is better maintained with steel ties. 
(3) Cost of maintenance of permanent road with steel ties remains 
almost constant after the second year, while with wooden ties it in- 
creases constantly with age, making the average cost greater than with 
the former. 
( 1) Kail fastenings are possible with steel ties which are at once safer 
and more easily maintained than those for wooden ties. 
(5) A good steel tie should not cost more than from 125 to 150 per 
cent, of the cost of wooden ties. 
(6) The "old material" value of a steel tie is greater than that of a 
wooden sleeper. 
" If, for comparison of the relative cost per mile of steel and wood, account is taken 
of the manufacture, transport, laying, maintenance, interest, and value of scrap, it 
is seen that there are few countries in the world where the exclusive use of wood ties 
is really economical. 
" For countries where climate and insects destroy wood sleepers in a few years this 
is evident ; but it speaks still better for steel sleepers that in Holland, which produces 
no steel and gets wood sleepers very cheaply by sea, all the railway companies have 
introduced metal sleepers without any pressure from the Government." 
KEQTJIRE3IE^TS AND COMPARISON OF DIFFERENT SYSTEMS OF SUPER- 
STRUCTURE. 
A very elaborate investigation into the merits of different systems of 
superstructure, with wooden and metallic longitudinal or cross-ties, has 
been published iu the " Organ fiir Fortschritte des Eisenbahnwesens " 
for 1886, by a high authority, W. Fuchs, replete with mathematical 
demonstrations and presenting a most thorough discussion on theoret- 
ical grounds, the results of which are given in the following notes : 
A. — The aggressive forces against which any system of superstructure must be prepared to 
stand, are, — 
(a) Vertical : pressure at the wheel, usually and properly taken as 7,000 kilo- 
grams (15,400 pounds). 
(b) Lateral: shocks representing a total effect of 5.5 tons, discounted by a re- 
lief of 2 tons from the opposite wheel, the total pressure being roughly 
5,000 kilograms, which may iucrease to the maximum 8,000 kilograms (11,- 
000 to 17,600 pounds). 
(c) Longitudinal: per rail not over 5,025 kilograms, adhesive weight of loco 
motive taken as 42,000 kilograms. 
B. — Requirements of systems. 
[a) Longitudinal ties. 
The manner, shape, and number of cross-connections seem to be of utmost impor 
tance ; blade-shaped connections are preferable to those with broad surface on account 
of the tendency of the latter to form humps in the road-bed ; a number of cross-con- 
nections is undesirable as counteracting the advantages of the long tie and introduc- 
ing the faults of the eross-tie system; the connection is best made at the rail joint, 
by which the favorable inlhience of such connection is utilized. If more connections 
* See p. 119, on Life of Metal Ties. 
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