===>> PRINCIPLE OF BRIDGE LOCATION<<===

===>> PRINCIPLE OF BRIDGE LOCATION<<===

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The basic principle for locating highway bridges is that the highway location should determine the bridge location, not the reverse. When the bridge is located first, in most cases the resulting highway alignment is not the best. The general procedure for most highways, therefore, is to first determine the best highway location and then determine the bridge site. In some cases, this will result in skewed bridges, which are more expensive to construct, or in locations where foundation problems exist. When serious problems of this nature occur, all factors such as highway alignments, construction costs of the bridge deck and its foundation, and construction costs of bridge approaches should be considered in order to determine a compromise route alignment that will give a suitable bridge site. This will include completing the transportation
planning process and the economic evaluation of the benefits and costs..

A detailed report should be prepared for the bridge site selected to determine whether there are any factors that make the site unacceptable. This report should include accurate data on soil stratification, the engineering properties of each soil stratum at the location, the crushing strength of bedrock, and water levels in the
channel or waterway.

 When the waterway to be crossed requires a major bridge structure, however, it is
necessary to first identify a narrow section of the waterway with suitable foundation conditions for the location of the bridge and then determine acceptable highway alignments that cross the waterway at that section. This will significantly reduce the cost of bridge construction in many situations.

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