1991. During most of the 1990s, Class 442 "Wessex Electric" units operated most of the fast services. Since 2007, services had been provided mostly by Class 444, supported by Class 450, electric multiple units. Unusually, the 450s, designed for stopping services, run certain fast services on Monday to Friday and most services on Saturday. This has led to complaints by people who disliked the high density 3+2 seating in some parts of these trains. Since January 2020, following an extended cascading process, partially refitted class 442 'Wessex Electrics' started to bolster the class 444 on both Portsmouth and Poole services. the Class 442s were withdrawn from service in March 2021. Topography of the line Gradients The central part of the route, from Guildford to Havant, runs through relatively thinly populated country. The line was designed on the "undulating principle"; that is, successive relatively steep gradients were accepted to reduce construction cost. In the days of steam operation this made the route difficult for enginemen. The line falls at 1 in 152 from Woking Junction to Worplesdon, then climbing at 1 in 111 for a mile and falling at 116 to Guildford. After gentle gradients, the line then climbs from Farncombe to Haslemere for nine miles, stiffening to 1 in 80. It then falls at 1 in 100 and 1 in 80 with intermittent respites to Liss, nine miles. A second climb of three miles (5 km) at 1 in 100 / 1 in 110 follows to a summit at Buriton Tunnel, then falling at 1 in 80, 1 in 100 and then more gently for 8 miles (13 km) to Havant. After Havant the gradients are considerably more gentle, with the exception of the short sharp climb at Portsmouth & Southsea on to the Harbour line. Chronology Stations in bold are still open. Woking Junction to Guildford: opened by the Guildford Junction Railway 5 May 1845 ; opened 1 March 1883; ; Guildford to Godalming: opened by the LSWR 15 October 1849 Guildford St Catherine's Tunnel; emergency station south of the tunnel open from 23 March 1895 to 1 April 1895 owing to the partial collapse of the tunnel; ; opened 1 May 1897; Godalming; renamed Godalming (Old) 1 January 1859; closed to passengers 1 May 1897; closed completely 1969; Godalming (junction immediately north of Old station) to Havant: opened by the Portsmouth Railway 1 January 1859 Godalming (New); renamed