British Rail Class 777

The replacement of the Class 507 and Class 508 fleet that has been in use on the Merseyrail commuter rail network since the late 1970s, had been proposed by Merseytravel as early as 2011.[10] While the Class 507 and 508 weren't the oldest electric multiple-units in use in Great Britain, Merseytravel had the oldest average fleet.[9]

In 2014, Liverpool City Region set out a 30 year rail vision, outlining investments that would and could be made to improve rail transport in the region. This included replacement of both the Class 507 and 508 trains with a new high capacity, dual voltage train fleet.[11] In 2015, Merseytravel gained approval to go out to tender to replace the train fleet.[12] In January 2016, Merseytravel announced that a total of five rolling-stock manufacturers had been shortlisted to build the new fleet – Bombardier, Siemens, CAF, Stadler Rail and a Mitsui/Alstom/East Japan Railway Company consortium.[13]

On 16 December 2016, Merseytravel announced Stadler Rail would manufacture a new fleet of 52 dual-voltage-capable articulated four-car units as part of a £460 million fleet replacement project.[3][14][15] Merseytravel has an option for a further 60 units.[3] Delivery of the Class 777 fleet was scheduled to start in mid-2019, and its entry into service was set for the following year.[14] The new trains would increase capacity by 60%, as well as cutting journey times due to faster acceleration.

The purchase was financed by Liverpool City Region itself, rather than an external agency such as a bank or rolling stock leasing company.[10] The Class 777 trainsets will therefore be owned by the regional public transport operator Merseytravel and leased to the franchise operator Merseyrail; this made Merseytravel the only public-sector mainline rolling-stock owner in the United Kingdom.[10] This is unlike the preceding fleet, owned by the private leasing agent Angel Trains.[10]

Merseytravel elected to have the new fleet's maintenance requirements addressed via a contract with Stadler; this arrangement included the modernisation of two existing traction maintenance depots (TMDs), at Kirkdale and Birkenhead North. For training purposes, a driver cab simulator has been installed in Kirkdale TMD.[10]

When the plan for an extension of the Kirkby line to Headbolt Lane was announced to the public, it was also revealed that the original order of 52 units had been increased to 53, in order that Stadler could supply sufficient units to operate the Kirkby line service once extended, as four diagrams will be required rather than three as at present.

To accommodate the new Class 777 trainsets, extensive infrastructure changes were necessitated.[10] These adaptations were performed under a rolling programme between October 2018 and May 2019; changes included adjustments to 97 platforms at 56 stations across the Merseyrail network, along with track realignments and other refinements, primarily for the purpose of improving passenger accessibility. Another cause for the alterations was the increased length of the new trainsets, which was addressed via a mixture of platform lengthening and signal repositioning where required. The programme was structured as to minimise disruption to Merseyrail's scheduled services wherever possible.[10] A new trackside Wi-Fi network, provided by Panasonic, was installed to provide continuous real-time connectivity between all trains and the Sandhills control centre, along with free internet access for passengers. New bulk power supplies were installed, along with eight new substations and miscellaneous cable upgrades, to provide greater quantities of electricity.[10]

Unlike the preceding trains, the Class 777 was designed to be operated without guards; however, the announced proposal to redeploy guards into other customer service roles within Merseyrail was subject to considerable criticism.[16] Accordingly, while the fleet was initially to be launched under driver-only operations, in September 2018 it was announced that there would be a second member of staff on board, ending a two-year dispute between the National Union of Rail, Maritime and Transport Workers (RMT) and Merseyrail.[17]

Merseyrail Class 777001 undergoing preliminary testing in St. Margrethen, before it had its temporary front door replaced.

Class 777010 at Hightown during Mixed-Traffic Testing, with its left side doors open.

Class 777010 (5S08) alongside 508125 (2U40) at Hightown during mixed-traffic testing.

During early October 2018 the bodyshells for the first unit were completed.[8] This unit subsequently underwent pre-delivery dynamic testing in both Switzerland and Germany during late 2019.[18][19] The first trainset, 777003, was delivered to Kirkdale TMD on 16 January 2020.[20][21] On 16 March 2020, the unit commenced test runs on the Kirkby branch of the Northern Line.[22] By October 2020, ten units had been delivered to Kirkdale TMD.[23]

In 2018, it was announced that a train configured as a battery electric multiple unit was to be tested on sections of unelectrified track.[1][24] Following the trial, it was announced in July 2021 that the units tested had been able to travel up to 20 miles without the need for recharging. The Liverpool City Region Combined Authority announced that the battery-powered trains will run to the new Headbolt Lane station at Kirkby which is due to open in 2023.[25]

In July 2021, full daytime testing of the units was underway.[26] In August 2021, the Office of Rail and Road authorised the introduction of these units into passenger operation.[9] As of December 2021, the date for passenger service has not been announced.