own ▁Boston ▁area . ▁Ve h icles ▁entering ▁Dow nt own ▁Boston ▁via ▁the ▁Sum ner ▁T unnel ▁must ▁take ▁I - 9 3 ▁north ▁to ▁the ▁exit ▁for ▁Government ▁Center ▁and ▁make ▁a ▁U - turn ▁to ▁access ▁the ▁entrance ▁r amp ▁to ▁I - 9 3 ▁south ▁( which ▁sil ently ▁car ries ▁Route ▁ 1 A ▁south ▁as ▁well ) ▁and ▁vice ▁vers a . ▁ ▁Route ▁description ▁ ▁Rh ode ▁Island ▁border ▁to ▁Att le bor o ▁A ▁short ▁segment ▁of ▁Route ▁ 1 A , ▁ ▁in ▁length , ▁in ▁Att le bor o ▁runs ▁from ▁U . S . ▁Route ▁ 1 A ▁at ▁the ▁Rh ode ▁Island ▁border ▁through ▁a ▁j unction ▁with ▁Inter state ▁ 9 5 , ▁before ▁heading ▁north ▁and ▁mer ging ▁with ▁Route ▁ 1 . ▁ ▁The ▁entire ▁length ▁of ▁this ▁segment ▁is ▁known ▁as ▁New port ▁Avenue . ▁ ▁North ▁Att le borough ▁to ▁D ed ham ▁This ▁segment ▁of ▁Route ▁ 1 A ▁extends ▁roughly ▁north ▁from ▁North ▁Att le borough ▁to ▁D ed ham , ▁passing ▁through ▁the ▁towns ▁of ▁P lain ville , ▁W rent ham , ▁Nor folk , ▁Wal pole , ▁Nor wood ▁and ▁West wood ▁on ▁the ▁way . ▁ ▁Prior ▁to ▁its ▁real ignment ▁along ▁I - 9 5 ▁and ▁I - 9 3 , ▁Route ▁ 1 ▁continued ▁north ▁along ▁the ▁Prov idence ▁Highway ▁towards ▁Boston ▁at ▁the ▁j unction ▁of ▁Route ▁ 1 A ▁and ▁that ▁road . ▁ ▁Boston ▁to