public. Between 2012 and 2017, the number of passengers and operating revenue declined; during 2016/17, the network carried 12.6 million passengers. Reasons presented for the reduction included the disruptive rail replacement effort across the network, which involved partial closures and the use of buses as temporary replacements, as well as the impact of cheaper petrol. New tram-train services The tram-train extension to Rotherham opened on 25 October 2018, using seven new Vossloh-built Class 399 Citylink articulated electric multiple units. Trams operate on Network Rail's line from Tinsley to Rotherham station and beyond to the Parkgate shopping centre, where services terminate on a short spur at the side of the railway, after travelling on the Supertram line from Cathedral to Meadowhall South/Tinsley. The station at Rotherham Central is a combined tram stop and railway station, with platforms 1 and 2 at Rotherham Central extended, with the new extensions numbered platforms 3 and 4 respectively. The stop at Parkgate is a single platform terminus. The first test run of the tram-train service (as far as Magna) was performed in the early hours of 10 May 2018, and the first gauging run all the way to Parkgate occurred in the early hours of 5 June 2018. The existing Siemens-Duewag Supertram fleet were not upgraded for tram-train operation, so were not registered under TOPS and cannot be used on the line as they lack the relevant Network Rail safety systems and crashworthiness. The tram-train scheme was first planned to be in service by 2015 but was delayed. The Class 399 units were built in 2015/16 with the first delivered in December 2015. Until the completion of the tram-train line, some were used to provide increased capacity on the existing Supertram network. They first entered service on 14 September 2017. On the opening day of tram-train passenger operations the service was suspended following a road traffic collision on the tram network involving one of the tram-train vehicles. The incident was caused by lorry operated by Ability Handling passing a red traffic light and caused the tram to be derailed. The service has also been suspended twice after faults were found on the Citylink units. The first suspension was on 9 April 2019, when the fleet was withdrawn to undergo safety checks, although service resumed the next day. The service was later suspended again on 14 December 2019, resuming three days later on 17 December. Services