THE BERLIN IRON BRIDGE COMPANY, »
front axle, and 22,000 pounds on the rear axle. This steam road roller load, however, effects mainly the floor system and the web rather
than the chords of the bridge.
There are two classes of connections used in bridges, viz., pin connections and riveted connections. Each is well adapted for its
proper condition. In spans of less than 100 feet, riveted connections do very well, but in large spans they are apt to work loose in time
and give trouble. As a general rule we recommend pin connected bridges, although we are prepared to make bridges with riveted con.
nections, wherever desired.
At the present time the quality of the iron used in iron highway bridges by all first-class builders is spjjrgM known that little need
be said on that subject. It does not pay for a bridge company to use poor iron, for the cost of labor in worker it is so much greater than
the cost of labor to work first-class iron, that it does not pay any Company to use anything but the very best of bridge iron. Good
bridge iron should have an ultimate strength of from 45,000 to 50,000 pounds per square inch, and elastic limit of not less than 26,000
pounds per square inch.
To parties contemplating iron bridges we would say that we are prepared to furnish plans, specifications, and estimates tor both substructures and super-structures. We have a corps of first-class engineers, and, whenever desired, can send one of our engineers to advise
with town officers as to location, number of spans, foundations, etc.
We are also using a large number of cylinder piers, shown on page 57, for locations where stone is expensive, or where the foundation is soft and unreliable. We have put in a large number of these cylinder piers, and in every case they have given the best of satisfaction, and often have been subjected to very severe floods, without injury.
When called upon for our services in preparing plans and estimates, or for giving advice, we make no charge as that is part of our
If you are building an iron bridge, build an iron bridge, that is, build as much of it of iron as possible.
It was formerly the custom to build the trusses of iron, and the floor beams and joists, of wood ; but as iron bridges came more
in general use, iron floor beams were introduced, and now a great many iron bridges are built with the joists of iron. If it is advisable to
build an iron bridge, it is advisable to build a good one, and to build as much of it of iron as is possible. We therefore recommend towns
to build their bridges entirely of iron, with the exception of the floor plank, as the extra expense of an iron joist over a wooden joist is very
small compared with the advantage to be derived.
EAST BERLIN, CONNECTICUT, U. S. A.