The High Speed 2 programme has many interdependent elements, including stations, infrastructure and railway systems. We raised concerns in our previous report that, given the scale of the programme and its future impact on the rail network, if the Department does not give enough attention to managing the interdependencies within the programme and other rail programmes, passengers and other services could suffer.38 From Crossrail, we have also seen the problems that can arise from poor integration of railway systems, and the delays and cost increases that this can cause.39 In our report on the programme 31 Qq 5, 40 32 Q 53; Letter from Department to Committee, 13 July 33 Qq 5, 49, 50, 57 34 Q 55 35 Committee of Public Accounts, High Speed 2: Spring 2020 update, Third Report of Session 2019–21, HC 84, 17 May 2020, conclusion 4 36 Q 55 37 Qq 5, 82 38 Committee of Public Accounts, High Speed 2: Spring 2020 update, Third Report of Session 2019–21, HC 84, 17 May 2020, para 6 39 Qq 22–23; Committee of Public Accounts, Crossrail: progress review, Ninety-Second Report of Session 2017–19, HC 2004, 3 April 2019, paras 15, 22; C&AG’s Report, Crossrail – a progress update, Session 2021–22, HC 299, 9 July 2021, para 13 14 HS2 Summer 2021 in 2021, we found that Crossrail had suffered delays and cost increases as a result of the failure to effectively install and integrate and integrate the systems required to operate the railway.40