2.20 As set out above, dependencies between contracts and projects has been a feature of the delivery strategy and had led to high levels of compensation events and increased costs during 2015 and 2016. As the programme progressed, the volume of dependencies between contracts and elements of the programme increased for the following reasons, adding to the risk that Crossrail Ltd would not be able to meet its target opening date and cost:
• delays to station contracts, the installation of track and systems in tunnels, and the development of signalling software on the train meant that critical work was pushed later into the programme schedule than planned;
• Crossrail Ltd's and sponsors' continued focus on the December 2018 opening date for the central section meant that they did not mitigate interface risk by extending the programme schedule; and
• increasing pressure on the likelihood of meeting the December 2018 opening date meant that Crossrail Ltd and contractors attempted to accelerate work on key contracts by increasing the workforce.
Crossrail Ltd's announcement in August 2018 that it would not complete the programme in time to open the central section in December 2018 resulted in an extension of the time that contractors would be on site, and further sharp cost increases.
2.21 Appendix Three includes four case examples that illustrate how the issues above manifested themselves on specific critical contracts. Examples of the issues that emerged include:
• access to work sites for contractors installing systems in the tunnel and station was delayed by late handover of assets by, for example, station contractors. Between February 2017 and December 2018, the forecast cost of the contract to install track and key systems in the tunnels increased by 80% from £532 million to £956 million. The forecast cost of the contract to provide communication and control systems equipment increased by 20% from £116 million to £139 million between April 2018 and December 2018;
• the acceleration and then prolongation of the contract to construct and fit-out Paddington Station resulted in an increase in forecast costs of 27%, from £449 million to £571 million between January 2018 and December 2018; and
• the development of software on the trains did not result in increases to the direct cost of the contract because the contract was based on a fixed price. However, delays to the readiness of the train and the signalling system and Crossrail Ltd's decision to commence signalling integration testing on the incomplete railway before the delayed train and signalling software was sufficiently developed reduced the availability of worksites for contractors to complete construction and fit-out work, which further exacerbated delays and cost increases.