The main part of the programme will go ahead as planned and should be delivered by March 2019, but the Cardiff to Swansea section will be delayed, to some time between 2019 and 2024. Revised dates for the completion of electrification work were published in early 2016, with electrification to Cardiff via Bristol Parkway, and the connection to Newbury planned by December 2018; the branch to Oxford from Didcot by June 2019; and the branch to Bristol Temple Meads from Wootton Bassett sometime between February 2019 and April 2020. In November 2016, the government announced that electrification work on the sections from Oxford to Didcot Parkway, Bristol Parkway to Bristol Temple Meads, Thingley Junction (near Chippenham) to Bath Spa and Bristol Temple Meads, and branches lines to Henley and Windsor had been indefinitely deferred. For Oxford and Bristol, the deferral was due to imminent resignalling and remodelling of the existing track layout. In July 2017, it was announced that the Cardiff-Swansea electrification project had been cancelled and that bi-mode trains would be used on the route. The Great Western main line is currently equipped with colour light signalling common to the rest of the United Kingdom. At the time of the Ladbroke Grove rail crash (1999), the ATP (Automatic Train Protection) warning system was under trial. In response to that incident, it became a requirement for all First Great Western trains to be fitted with ATP. When the Department for Transport first released the train specification for the new trains for the IEP in November 2007, it was stated that the Great Western main line would be upgraded to ETCS level 2 and ERTMS Level 2 in-cab signalling. Some or all of the resignalling work will be carried out alongside the electrification work. Signalling Solutions is to resignal the 12 miles from Paddington to , including the Airport branch, as part of the Crossrail project. In November 2008, Westinghouse (subsequently known as Invensys Rail, and now part of Siemens Rail Automation) was awarded a £20M contract for a 30-month programme of signalling enabling work. Over a series of 12 commissionings, Invensys Rail will re-lock the existing Reading Station and Spur interlockings to three new WESTLOCK Interlocking units, re-control the remaining 18 relay interlockings and move signalling and telecommunications control from Reading Station to the new Thames Valley Signalling Centre at Didcot. The work culminates in a final commissioning, scheduled for 5 December 2010 and paves the way for future stages of the remodelling programme.