During the early days of research, the BRB were contemplating raising the general operating speeds of passenger trains and wished to know the effect of running at high speeds over specific track features. Tests were conducted overnight at Wrinehill, near Madeley just south of Crewe on the WCML using a Deltic amongst the various test locomotives. These locos were usually to be found running on the ECML at 100 mile/h and were chosen as the representative locos which would exert the maximum vertical force on the track (known as the 'P2 Force') when traversing a 'dipped' rail joint at speed. The tests were conducted overnight on Saturday 30th October 1971, Test Car 4 used on one of the trains which consisted of Freightliner wagons with the LMW hauled by E3112. This is one of the tests using E3173 as the loco under test.