id - frame ▁bridge ▁ ▁Single ▁span ▁ ▁Single ▁span ▁rig id - frame ▁brid ges ▁are ▁typically ▁made ▁of ▁rein for ced ▁concrete ▁and ▁are ▁commonly ▁used ▁on ▁park ways ▁and ▁other ▁road ways . ▁ ▁This ▁design ▁is ▁an ▁efficient ▁use ▁of ▁material ▁as ▁the ▁cross ▁section ▁at ▁mid - span ▁is ▁relatively ▁narrow ▁and ▁the ▁amount ▁of ▁concrete ▁needed ▁at ▁the ▁ab ut ments ▁is ▁reduced . ▁ ▁The ▁narrow ▁section ▁at ▁mid - span ▁gives ▁the ▁bridge ▁profile ▁a ▁slight ▁arch ▁shape ▁making ▁this ▁design ▁particularly ▁useful ▁when ▁large ▁head room ▁is ▁required . ▁The ▁profile ▁also ▁makes ▁the ▁bridge ▁more ▁architect ur ally ▁ple asing ▁than ▁a ▁beam ▁bridge . ▁R ig id - frame ▁design ▁may ▁be ▁the ▁most ▁efficient ▁bridge ▁type ▁for ▁sp ans ▁between ▁ 3 5 ▁and ▁ 8 0 ▁feet . ▁ ▁If ▁steel ▁is ▁used , ▁the ▁economic ▁advantage ▁extends ▁to ▁sp ans ▁of ▁ 1 2 0 ▁feet . ▁ ▁V - sh aped ▁ ▁A ▁v - sh aped ▁rig id ▁frame ▁is ▁an ▁efficient ▁way ▁to ▁support ▁a ▁longer ▁bridge ▁where ▁using ▁only ▁one ▁span ▁isn ' t ▁feas ible . ▁ ▁Each ▁v - sh aped ▁pier ▁supports ▁the ▁deck ▁in ▁two ▁places ▁while ▁only ▁requiring ▁one ▁foundation . ▁ ▁The ▁b ending ▁moments ▁experienced ▁in ▁the ▁pi ers ▁are ▁minimal , ▁allowing ▁significant ▁redu ctions ▁in ▁the ▁foundation ▁size . ▁ ▁Additionally , ▁the ▁effective ▁length ▁of ▁each ▁span ▁is ▁short ened ▁compared ▁to ▁the ▁sp ans