"HST125" of the "Castle Class" of the Great Western Railway is running as train 2P17 from Penzance to Plymouth, crossing the Royal Albert Bridge over the Tamar river at Saltash. Power car 43 # 156 "Mean Castle" is in front and 43 # 042 "Tregenna Castle" in the rear. This trains were shortened to 4 intermediate cars with automatic doors and second class only for the services between Plymouth and Penzance and are based in Plymouth Laira depot. The trains, still approved for 125 mph (200 km/h), travel at a maximum of 75 mph here, but mostly in the 65 mph (105 km/h) range. The two diesel power cars of class 43 with MTU engines each have an output of 1678 kW (2250 HP). The Royal Albert bridge is 667 meter long and 52 meter high, opened in 1859 and constructed by I.K.Brunel. The Tamar river is the border between Devon and Cornwall.