much a political effort as it was an engineering one. By the 2010s, the region's rail infrastructure was relatively worn-out and prone to unreliability. Modernisation efforts would therefore focus not only on improving absolute speeds but on reducing failure rates as well. This work is being undertaken as a multiagency effort, involving not only infrastructure changes carried out by Network Rail and various civil engineering companies, but also the procurement of new rolling stock and other efforts. It was recognised early on that, for the intercity services to be meaningfully speeded up, slower regional trains could not feasibly be overtaken or avoided on the mostly twin-track line, so that services overall would need to be accelerated. There has also been an aspiration to increase the number of trains between Norwich and London to three per hour, although capacity constraints such as the single-track section in the vicinity of the Trowse Swing Bridge would need to be overcome to facilitate this. Some services have been transferred from Greater Anglia's management to other rail operators. On 31 May 2015, the Liverpool Street to Enfield Town, Cheshunt (via Seven Sisters) and Chingford services, as well as the Romford to Upminster service, were transferred to London Overground Rail Operations. On the same day, the Liverpool Street to Shenfield stopping services were also transferred to the TfL Rail concession managed by MTR. In June 2015, an Abellio (60%) / Stagecoach (40%) joint venture, FirstGroup and National Express were shortlisted to bid for the franchise. In December 2015, it was announced that Stagecoach had pulled out of the joint bid with Abellio, and that Abellio would continue the bid alone. In August 2016, it was announced that Abellio had successfully retained the franchise until 2025. One commitment of the new franchise period is the purchase of 1,043 new carriages, 660 from Bombardier Transportation's Derby Litchurch Lane Works with the remainder being built by Stadler Rail. In January 2017, Abellio announced that, subject to gaining DfT approval, it had agreed to sell a 40% stake in the business to Mitsui. The sale was completed in March 2017. Reportedly, Greater Anglia has incorporated numerous planning and operational practices of the Japanese railways, such as the use of digital twin simulation software for analysing performance and developing its timetables, since the acquisition. In 2021, the francise was extended until 20 September 2026. Industrial action In August 2017, amidst a