▁Motor way ▁was ▁fixed ▁in ▁the ▁spring ▁of ▁ 1 9 5 7 . ▁ ▁Design ▁Each ▁carriage way ▁is ▁carried ▁on ▁a ▁separate ▁structure . ▁Each ▁carriage way ▁is ▁supported ▁by ▁five ▁riv et ed ▁steel ▁g ird ers . ▁There ▁are ▁ 2 , 2 2 5 ▁tons ▁of ▁struct ural ▁steel work . ▁ ▁Const ruction ▁Const ruction ▁of ▁the ▁Don c aster ▁by pass ▁started ▁on ▁ 2 2 ▁June ▁ 1 9 5 9 . ▁There ▁were ▁ 2 8 ▁brid ges ▁in ▁the ▁contract ▁for ▁the ▁Don c aster ▁by pass , ▁including ▁five ▁railway ▁brid ges . ▁ ▁The ▁fabric ation ▁of ▁the ▁steel work ▁for ▁the ▁bridge ▁took ▁place ▁at ▁the ▁West ▁B rom wich ▁Works . ▁The ▁steel ▁super structure ▁for ▁the ▁bridge ▁was ▁launched ▁from ▁one ▁end ▁of ▁the ▁bridge ▁on ▁an ▁emb ank ment . ▁The ▁steel ▁fabric ation ▁was ▁sp rayed ▁with ▁z inc . ▁The ▁concrete ▁and ▁steel ▁design ▁is ▁known ▁as ▁composite ▁construction . ▁ ▁The ▁concrete ▁be ams ▁were ▁made ▁by ▁Fer ro ▁Con crete ▁and ▁Stone ▁Co . ▁( N orth ▁Not ts ) ▁Ltd ▁of ▁Ret ford . ▁ ▁The ▁by pass ▁was ▁built ▁by ▁a ▁cons ort ium ▁including ▁Holland , ▁Hann en ▁& ▁Cub itt s , ▁on ▁a ▁£ 6   mill ion ▁contract . ▁ ▁Str ucture ▁The ▁south ▁side ▁of ▁the ▁bridge ▁is ▁in ▁War ms worth , ▁and ▁the ▁north ▁side ▁is ▁in ▁S pro t br ough ▁and ▁C