AS A RULE , MEMBERS OF THE PROFESSION (ENGINEERS) MUST CONSIDER FUNDAMENTALS OF THE DESIGN & SCOPE BEFORE STARTS UP

Engineers must consider fundamentals of the law code manual,as a rule in deciding the design and scope of variable items and structural details related to the construction of the structure For example in the case of the length of the clear span and number of spans it must have as small as possible,since the piers obstruct flow and particularly inthe mountainous region ,where the torrential velocities prevail ,it is better to span from bank to bank using no piers if possible. The abutment and the pier section sections should be so designed as to withstand safely the worst combination of loads and forces as specified in the IRC code for which bridges and the culverts on NH should be designed for one lane of Class 70R or two lanes of class "A"loading,whichever produces more severe stresses in the various members under construction. For culverts with small spans designed for IRC Class 70 R loading or 2 lanes of IRC  Class "A" loading,the abutment sections may be adopted as per the provision made and designed separately.In case of bridges detailed designs have to be carried out to arrive at the safe sections .The base widths of the abutments and the pier depends upon the bearing capacity of the soil .The pressure at the toe of the abutment should be worked out to ensure that the soil is not overstressed .In scourable beds , the length of the pier should be kept minimum and preferably made circular inthe case of skew bridges . Analysis of the variable items of the work to be carried out must satisfy the requirements of the design and scope. In case of the small bridges a minimum clear road way of 4.5 mts for a single lane bridge and 7.5 mts for two lane bridge between the inner faces of the kerbs or wheel guards .Extra provison should be made for foot paths ,if so required . The length of a culvert should be such that the distance between the outer faces of the parapets will equal  the full designed width of the formation of the road .Any proposed widening of the road formation in the near future should also be taken in to account in fixing the width of the culvert .