the british rail class 318 is an electric multiple unit (emu) train, which operates exclusively in the strathclyde partnership for transport network in west central scotland. the units were introduced fully on 29 september 1986 as part of the electrification of the ayrshire coast line between glasgow central and ayr/ardrossan with alternating current (ac) overhead lines. usage was extended to largs in january 1987. they were also used on the inverclyde line in small numbers and on rare occasions the cathcart circle lines (including to neilston and newton).