▁loops ) ▁which ▁turn ▁the ▁rid ers ▁ups ide ▁down . ▁Over ▁the ▁years ▁there ▁have ▁been ▁many ▁roll er ▁co aster ▁manufact ur ers ▁with ▁a ▁variety ▁of ▁types ▁of ▁roll er ▁co aster s . ▁ ▁Man ufact ur ers ▁today ▁include : ▁ ▁B oll iger ▁& ▁M ab ill ard ▁ ▁Ger st la uer ▁ ▁Great ▁Co aster s ▁International ▁ ▁Int amin ▁ ▁Mack ▁R ides ▁ ▁Premier ▁R ides ▁ ▁Rock y ▁Mountain ▁Const ruction ▁ ▁V ek oma ▁ ▁Zam per la ▁ ▁Rail ways ▁ ▁Am usement ▁park ▁rail ways ▁have ▁had ▁a ▁long ▁and ▁varied ▁history ▁in ▁American ▁am usement ▁par ks ▁as ▁well ▁as ▁over se as . ▁Some ▁of ▁the ▁earliest ▁park ▁trains ▁were ▁not ▁really ▁trains ; ▁they ▁were ▁t rolle ys , ▁which ▁brought ▁park ▁pat rons ▁to ▁the ▁par ks ▁on ▁regular ▁rail ▁lines ▁from ▁the ▁cities ▁to ▁the ▁end ▁of ▁the ▁rail ▁lines ▁where ▁the ▁par ks ▁were ▁located . ▁As ▁such , ▁some ▁older ▁par ks , ▁such ▁as ▁Ken ny wood ▁in ▁Pennsylvania , ▁were ▁referred ▁to ▁as ▁t rol ley ▁par ks . ▁The ▁earliest ▁park ▁trains ▁that ▁only ▁operated ▁on ▁lines ▁within ▁the ▁park ' s ▁boundaries , ▁such ▁as ▁the ▁one ▁on ▁the ▁rid able ▁mini ature ▁Ze ph yr ▁Rail road ▁in ▁Dor ney ▁Park , ▁were ▁mostly ▁custom - built . ▁A ▁few ▁par ks ▁trains ▁( such ▁as ▁the ▁Disney land ▁Rail road ▁and ▁Dol lywood ▁Express ) ▁operate