The previous major procurement of rollingstock for the
Melbourne rail network occurred in 2003, when franchisees
Connex ordered 62
electric multiple units (EMUs) and 58
Alstom X'Trapolis 100 EMUs respectively, as part of their franchise agreements to replace older
 However, the Siemens units suffered major braking issues over the following decade, causing their repeated withdrawal from service;
 when the
State Government tendered for 18 further 6-carriage trains in 2007, it restricted bids to the previous two models ordered and awarded the contract to Alstom.
 Several further orders were placed for X'Trapolis trains over the next 10 years.
Public Transport Development Authority (later branded as Public Transport Victoria or PTV) was created in 2011 by the state government under Premier
Ted Baillieu with the intent of, among other things, running major studies into the operation of the metropolitan rail network.
Network Development Plan Metropolitan Rail, released publicly in early 2013 in the partial fulfilment of this objective, was designed as a series of concrete proposals for the expansion and consolidation of the rail network over the following 20 years.
 The NDPMR's first stage, intended to be completed before 2016, acknowledged the need for an interim solution of several more X'Trapolis trains to overcome major constraints, as well as recommending the internal reconfiguration of Siemens and
Comeng trains to increase capacity, but identified the provision of new rollingstock as critical to the cost-effective use of existing railway infrastructure.
Among the deficiencies of existing rollingstock noted by the NDPMR were "multi-purpose" designs intended to strike a balance between
commuter rail and
metro operations, and the failure of existing trains to use the entire length of metropolitan
platforms. The NDPMR rejected
double-deck trains on the basis that they would increase
dwell time at crowded stations, and argued that 220-metre trains, formed by operating the existing 3-car sets as 9-car trains, would require extensive and prohibitively expensive infrastructure works, particularly in the
City Loop. Instead, it recommended the procurement of single-level trains with a fixed number of cars, increased standing room and a length of 153 metres (502 ft), with the capacity for expansion to 220 m (720 ft) upon the opening of the
Melbourne Metro tunnel. The NDPMR envisaged these trains with a maximum capacity of 1100 and 1600 passengers respectively.
The NDPMR envisaged that these high-capacity trains would completely replace the Comeng fleet by 2032, and be used primarily on the
Dandenong line created by the Melbourne Metro. Furthermore, it identified the need for the new trains to include
cab signalling to reduce the
headway required between trains, and for the construction of new maintenance facilties at several points on the network.
Prior to the
2014 Victorian election, then premier
Denis Napthine promised an order of 25 HCMTs if his incumbent
Liberal-National Coalition government was returned for a second term.
Order and design phase
In June 2015, the new
Government of Victoria under Premier
Daniel Andrews announced that expressions of interest would be requested for 37 new trains to be delivered and maintained for the Melbourne rail network.
In November 2015, three consortia were shortlisted to build and maintain 37 trains:
In March 2016 the order was increased to 65.
In September 2016 the contract was awarded to the Evolution Rail consortium. New depots to maintain the trains will be built in
Pakenham East and
 By September of the following year, a full-scale mock-up of two carriages had been constructed and was presented to Minister for Public Transport
 The mock-up was made available to
drivers, technicians, representatives of the
Public Transport Users Association and passenger groups including the visually impaired and those with physical disabilities. The Evolution Rail consortium noted that this last stage in the design process marked the fulfilment of the project's first major contractual obligation.
In late 2017, the Locomotive Division of the
Victorian Rail Tram and Bus Union lodged proceedings in the
Federal Court of Australia against Metro Trains, claiming that the consortium, government and Metro planned to introduce a lower standard of training for operators of the HCMT. It furthermore refused to support the implementation of the new rollingstock unless all electric train drivers were trained in the operation of the HCMT.
 Among the union's objections to the project are the necessary changes in work practice and the increased automation of certain processes.
 This followed criticism by the
Australian Workers' Union of the decision to award the contract to Evolution Rail instead of Bombardier, the latter of which had an established manufacturing operation in
 The government announced the awarding of several subcontracts for the project in December.
The HCMTs are expected to begin testing in November 2018 and enter passenger service on the
Pakenham lines in 2019.