▁The ▁line ▁primarily ▁oper ates ▁E MD ▁locomot ives , ▁including ▁GP 4 0 ▁style ▁engines ▁as ▁well ▁as ▁engines ▁like ▁GP 1 6 s ▁that ▁have ▁since ▁been ▁re built ▁from ▁other ▁older ▁models ▁like ▁GP 7 s ▁that ▁were ▁initially ▁purchased ▁by ▁the ▁BB ▁early ▁on . ▁ ▁For ▁the ▁most ▁part , ▁most ▁engines ▁are ▁assigned ▁a ▁number ▁composed ▁of ▁the ▁rail road ' s ▁initial s ▁and ▁a ▁new ▁designated ▁number ▁they ▁received ▁upon ▁joining ▁the ▁BB ' s ▁engine ▁ro ster . ▁ ▁These ▁numbers ▁gradually ▁rise ▁in ▁more ▁or ▁less ▁increment al ▁order ▁with ▁each ▁individual ▁engine , ▁though ▁some ▁engines ▁still ▁retain ▁their ▁original ▁paint ▁schemes ▁and ▁numbers . ▁▁ ▁Engine ▁ro ster : ▁▁ ▁E MD ▁GP 7 ▁( BB ▁ 1 0 1 , ▁formerly ▁of ▁the ▁Richmond , ▁Fred r icks burg ▁and ▁Pot om ac ▁Rail road ▁that ▁was ▁eventually ▁ref urn ished ▁with ▁its ▁original ▁R F & P ▁paint ▁scheme ▁and ▁number ) ▁▁ ▁x 6 ▁E MD ▁GP 1 6 ▁( BB ▁ 1 , ▁BB ▁ 2 , ▁BB ▁ 3 , ▁BB ▁ 8 ▁and ▁BB ▁ 9 , ▁BB ▁ 8 ▁also ▁retained ▁its ▁original ▁paint ▁scheme ▁for ▁a ▁while ▁after ▁purchase ▁by ▁the ▁BB ) ▁▁▁ ▁Bald win ▁R S - 4 - TC ▁( BB ▁ 4 ) ▁ ▁x 3 ▁E MD ▁GP 4 0 ▁( BB ▁ 5 , ▁BB ▁ 6 ▁and ▁BB ▁ 7 ) ▁▁▁ ▁x 2 ▁E MD