. The Street railway journal . ble. Cantileverbridges have been built in many places, where simple trussescould have been erected more economicallv, and therefore erected without falsework in certain locations. The steelarch is to be recommended in all cases where conditions arefavorable as being economical as well as on account of thegraceful appearance. The locations favorable for such anarch are where nature has already provided the skewbacksfor the same, viz.: where the shores on both sides of the riverconsist of solid rock and rise considerably above the surfaceof the water, as is the cas
. The Street railway journal . ble. Cantileverbridges have been built in many places, where simple trussescould have been erected more economicallv, and therefore erected without falsework in certain locations. The steelarch is to be recommended in all cases where conditions arefavorable as being economical as well as on account of thegraceful appearance. The locations favorable for such anarch are where nature has already provided the skewbacksfor the same, viz.: where the shores on both sides of the riverconsist of solid rock and rise considerably above the surfaceof the water, as is the case of the site of the Niagara Fallsand Clifton Bridge. This structure also had to be erectedon the cantilever principle. This arch has a span of 840 centers of pins, and is therefore the largest span of its kind in the world. MOVABLE BRIDGES If a bridge crossing a navigable stream is not high enoughabove the water level to provide the necessary clearance forthe requirements of navigation, it becomes necessary to con-. OHIO RIVER BRIDGE BETWEEN NEWBORT, KY., AND CINCINNATI, OHIO tlie latter would have been more apiuopriatc in their some cases it is possible to design simple truss spans sothat they can be erected on the cantilever principle, whichshould be done where the conditions make it practicable. Forinstance, in the case of the double-track cantilever bridgeover the Monongahela River, with a clear span of 800 ft., thecantilever type was the most appropriate, in fact the onlypractical design which could have been selected in order toconi|)ly with the requirements and local conditions and alsofor economy. SUSPENSION BRIDGES Suspension bridges of the usual type are generally not tobe recommended, as they lack that rigidity which is essentialin a first-class bridge for railway traffic. Special types ofsuspension bridges with eye-bar chains and spandrel bracedstiffening trusses can be designed so as to produce a structurerigid enough for railway traffic. THE
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectstreetr, bookyear1884
