- AD A ▁demand ▁response ▁tri ps ▁are ▁provided ▁on ▁a ▁first - come , ▁first - ser ved ▁basis ▁and ▁are ▁subject ▁to ▁capacity ▁constraints . ▁ ▁A - train ▁ ▁D CT A ▁oper ates ▁the ▁A - train , ▁a ▁regional ▁passenger ▁rail ▁line ▁connecting ▁Car roll ton ▁and ▁D ent on , ▁to ▁meet ▁growing ▁transport ation ▁dem ands ▁in ▁eastern ▁D ent on ▁County . ▁The ▁A - train ▁par alle ls ▁Inter state ▁ 3 5 E ▁and ▁is ▁a ▁logical ▁extension ▁with ▁the ▁Dallas ▁Area ▁Rap id ▁Trans it ▁Green ▁Line ▁at ▁Tr inity ▁M ills ▁Station ▁in ▁Car roll ton . ▁ ▁It ▁has ▁five ▁stations , ▁two ▁in ▁D ent on ▁and ▁three ▁in ▁Lewis ville , ▁and ▁opened ▁June ▁ 2 0 , ▁ 2 0 1 1 . ▁ ▁R id ership ▁D CT A ▁rid ership ▁fl uct u ates ▁greatly ▁with ▁the ▁academic ▁calendar , ▁as ▁a ▁considerable ▁portion ▁of ▁passengers ▁are ▁UN T ▁and ▁T W U ▁students , ▁fac ulty , ▁and ▁staff . ▁ ▁As ▁an ▁example , ▁D CT A ▁average ▁daily ▁fixed - route ▁rid ership ▁in ▁September ▁ 2 0 0 8 ▁( d uring ▁the ▁fall ▁sem ester ▁at ▁UN T ▁and ▁T W U ) ▁was ▁ 1 3 , 8 4 0 ▁passenger ▁tri ps , ▁while ▁in ▁July ▁ 2 0 0 9 ▁( out side ▁the ▁main ▁academic ▁periods ) ▁it ▁was ▁ 2 , 6 9 5 .