▁Due ▁to ▁winter ▁weather ▁conditions , ▁sections ▁of ▁I - 7 0 ▁are ▁regularly ▁closed ▁during ▁the ▁winter ▁and ▁are ▁expensive ▁to ▁maintain . ▁ ▁Inter states ▁I - 2 2 5 ▁and ▁I - 2 7 0 ▁provide ▁connection ▁through ▁heavy ▁traffic ▁cor rid ors ▁in ▁the ▁Den ver ▁Area . ▁I - 7 6 ▁connect s ▁the ▁Den ver ▁area ▁with ▁I - 8 0 ▁in ▁Neb r aska ▁to ▁the ▁n ortheast . ▁ ▁Highway ▁Saf ety ▁ ▁In ▁ 2 0 1 1 , ▁Colorado ▁ranked ▁among ▁the ▁five ▁dead liest ▁states ▁for ▁de br is / l itter – ca used ▁vehicle ▁acc idents ▁per ▁total ▁number ▁of ▁registered ▁vehicles ▁and ▁population ▁size . ▁Fig ures ▁derived ▁from ▁the ▁National ▁Highway ▁Tra ffic ▁Saf ety ▁Administration ▁( N HT SA ) ▁show ▁at ▁least ▁ 1 6 ▁persons ▁in ▁Colorado ▁were ▁killed ▁each ▁year ▁in ▁motor ▁vehicle ▁coll isions ▁with ▁non - fixed ▁objects , ▁including ▁de br is , ▁dump ed ▁l itter , ▁animals , ▁and ▁their ▁car c ass es . ▁ ▁In ▁the ▁United ▁States , ▁including ▁Colorado , ▁most ▁civil ▁av iation ▁inc idents ▁are ▁investig ated ▁by ▁the ▁National ▁Transport ation ▁Saf ety ▁Board ▁( NT SB ), ▁as ▁well ▁as ▁the ▁Colorado ▁Bureau ▁of ▁Investig ation ▁( C BI ). ▁When ▁investig ating ▁an ▁av iation ▁dis aster , ▁N T SB ▁investig ators ▁piece ▁together ▁evidence ▁from ▁the ▁crash ▁and ▁determine ▁the ▁likely ▁cause ( s ), ▁whereas ▁the ▁C