Introduction

Network Rail is the company set up by the government to look after the infrastructure of the railways. This means the upkeep of tracks, bridges, tunnels and so on. This case study is about the planning that went into the repair of a major viaduct. The Leven Viaduct on the north-west coast was built in 1857. The action of the sea and time had weakened it so that Network Rail was only left with two options, either to repair the viaduct or re-route all trains around it. Option 1 was costly but Option 2 would put an unacceptable strain on the West Coast main line. It was therefore decided to repair the viaduct.

Operations planning

All engineering projects require careful planning. Key objectives were set, along with a budget. Engineers needed to complete the repair within budget and in such a way that there would be no future line closures and no major maintenance for at least 25 years. The success of the plan would also be judged by other factors such as:

• having no safety issues during the project
• having good relationships with communities
• minimising disruption to rail users.

The project was a huge undertaking requiring £14 million of investment. Key issues to be considered included:

• the possible effects of bad weather
• health and safety issues
• the environment
• possible disruption to rail users
• obtaining the correct steel.

Roles

The work required a number of different tasks and therefore job roles. Some of these could come from internal sources, others had to be brought in from outside. They included planners, engineers, managers and building contractors.

Critical path analysis

Major construction projects such as the viaduct require a number of steps. Some are dependent on previous steps, for example, new track cannot be laid before old track is taken up, whilst others can be carried out at the same time. Critical path analysis involves looking at each task and working out the most efficient sequence for carrying them out. A network diagram is constructed which shows which activities can be carried out at the same time and which are dependent on others. From this the shortest (i.e. most efficient) order can be established. With the Leven Viaduct, there were so many processes that engineers used spreadsheets and other computer programmes to help them build the path.

Planning

Critical path analysis is a very detailed process.  It can be costly and time consuming.  However, it can also provide a detailed 'map' to show planners where each process should take place.  The comprehensive planning was worth it as it allowed the project to be completed without any problems.

Conclusion

The repair of the viaduct was completed in 16 weeks - half the time it was originally thought it would take. This was due to good planning and efficient working. The £14 million investment means the viaduct should be good for another 140 years.