Technical debt refers to the costs of having to go back and resolve problems that arise because an earlier decision was made to take an easy option, instead of the best one. Based on two major rail projects in London. The £14.8bn Crossrail project will finish more than 2 years late and 20% over budget. The £7.bn Thameslink project is running to plan and nearing completion. This paper will look at three factors causing the difference:
1. The physical structure of the projects and their relative complexity.
2. The insidious effect of Technical Debt on the delayed opening of Crossrail.
3. The governance factors leading to the 'Crossrial disaster' and how Crossrail messaging largely caused the 'disaster'.
There are powerful lessons to learn particularly when scoping major projects.
