There is no doubt that tunnelling in any situation is a challenging task with many different considerations that need to be taken into account.
We at Bluey have seen many of these issues first-hand, having worked in tunnel waterproofing for nearly 15 years. In fact, the experience of our engineers in Australia, Europe and Asia extends back to the 1980s.
However, in recent years, our team has noticed a real difference in the way tunnels are built, which could have serious implications to how all parties interact on projects in the future.
Modern tunnel construction
While this piece shouldn’t be taken as having a go at the construction industry, which is under its own stresses, project managers are beginning to compress all the different activities in the small environment of a tunnel.
In recent times, trucks will be excavating dirt and removing spoil at the same time that concrete trucks are going in and workers are inserting bolts into the rock. During this process, we are often trying to install our membrane while people are pouring concrete behind that.
We understand that due to the time and budget pressure on infrastructure leaders, this is going to become commonplace moving forward. With this in mind though, all parties need to recognise and understand the importance of quality work and quality safety outcomes.
Traditional tunnel construction
In the early days of our experience, some 20-30 years ago, project managers in liaison with parties would separate the different activities to ensure each was done up to standard. For example, all the excavation would be completed, then the waterproofing and finally the concreting guys – who we often wouldn’t see!
While this depended on the length of the tunnel, its purpose and the attitude of the stakeholders, this process meant each party was not working in the other’s coattails.
Recent Sydney Tunnel Project
Bluey have just completed a major project under the Sydney CBD. The project was a throwback to the good, old-fashioned, traditional tunnel construction processes which really highlighted the importance of access in the tunnel environment. The main contractor did a superb job excavating the tunnel prior to Bluey joining on site, this meant we had uninterrupted access to the tunnel and were able to work in a continuous unimpeded method.
As a result, we’ve been able to install the membrane under ideal conditions where there is no interruptions and risk of damage. In fact, I can safely say that we have achieved productivity targets 5-10 per cent higher in this tunnel than similar projects in the recent past.
It is important to note some of the challenges facing tunnel work due to the busy nature of today’s construction. If excavation is going on at the same time as waterproofing, this can cause dusty conditions and workers might have to wear breathing apparatus while installing membrane.
There is also the need to coordinate the delivery of membrane in line with construction trucks entering and leaving the tunnel and ensuring the membrane isn’t damaged by large vehicles moving close by.
While the recent Sydney tunnels are a good example of what can be achieved through coordination, this isn’t going to be possible in all situations. As such, all parties need to be able to come together at an early stage to talk about the issues they will face and implementing processes to ensure each step of tunnel is completed on time, safely and up to standard.