sentences:  West Midlands Trains operate a total of 35 two-car and three-car units, 27 of which had been ordered by predecessor London Midland, who originally planned for them to enter service by the end of 2010 on services to and from Birmingham Snow Hill, replacing Class 150s.The original West Midlands Trains sets have revised front ends with end gangways which make the trains look like the Electrostar family of units.From 1 September 2011, the units started operating on the Snow Hill Lines with some weekend work from Birmingham - Hereford.