Productivity on T5 is reaching unprecedented levels for a construction project thanks to a revolution in logistics. Mark Hansford finds out how push has come to pull.
Pull logistics should be the next big thing to hit UK construction. Using the methodology on T5, BAA reckons it has raised productivity from a typical construction site average of 55-60% to 80-85%.
The idea itself is astonishingly straightforward. Simply cast off the traditional mentality where the supply chain will effectively 'push' materials into the site, determining what is supplied and when. In its place apply the 'pull' mentality, where nothing moves down the chain until the site is ready to accept it.
The benefits are obvious too.
From a financial point of view, it is simply good use of capital to only have - and pay for - materials when they are needed. Reliability is improved as materials are not left lying around on site where they can deteriorate or get damaged.
And, perhaps, most importantly, it means that the timing of deliveries can be strictly controlled.
Because on T5, timing of deliveries is everything.
'There are three or four key reasons on T5 to treat logistics differently to anything the construction industry has done before, ' says Doug Black, logistics performance manager for BAA.
'A few city centre contracts might come close, but nothing matches this project in terms of size, complexity and logistical restraints.'
First, there are environmental concerns over the congestion that could be caused by the sheer volume of site traffic and deliveries. The public inquiry ruling recognised this and put heavy constraint on the roads that can be used and times of day that vehicles can use them. Nothing can be delivered to site before 9am and during the evening rush between 5pm and 7pm, and all deliveries must cease at 9pm.
With just one entrance to the entire 250ha site - another public inquiry demand - this makes for high pressure on slots. In November, the number of vehicles entering the site peaked at 220230 vehicles per hour Second, there are space constraints - not surprising on a site with 36 work areas. 'With the number of workfaces we have, there is literally not the room to store materials for any length of time - and by that I mean 24 hours, ' says Black.
The third constraint is another imposed by public inquiry. All bulk materials must come to site by rail, via the Colnbrook terminal (see box).
Black's final constraint is the fact that a major component to delivering the project on time and to budget will be the reliability of the delivery of materials to site. 'A root cause analysis of why, on an average construction site, 40% of activities don't happen, shows that invariably, it's because the material is not there, is of poor quality or has been damaged, ' he says.
If that explains the need for a new approach to logistics, the 'T5 Production Strategy' builds the framework to make it happen.
Major objectives of this include reducing the risk of congestion to site users and stakeholders (such as local residents); increasing the productivity and reliability of construction teams on site; and looking for value improvements in the supply chain. The idea here is to work with the first, second and third tier suppliers to take the unnecessary cost out of their business. Currently, BAA is starting to work on its second-tier suppliers.
Achieving these objectives is where pull logistics comes in. And for that, BAA is using Project Flow, a tool with its origins in lean manufacturing but specifically structured for the construction industry.
'On a daily basis, the teams at the workfaces sit down and ask 'where are we today, so where will we be tomorrow?' Black explains.
Each workface enters its demands for the next day into Project Flow, which then aggregates the demands and drives the materials through the system.
'The logic is simple, ' says Black. 'And it means that if teams are ahead of schedule there is nothing to stop them ploughing on, as long as this doesn't impact on others on site. Likewise, if there is an issue on site that slows - or stops - work, you don't get a build up of materials. It allows the supply chain to be very responsive.'
This is radical thinking, and a lot of it has been alien to suppliers, admits Black. 'For most, this is good stuff that will benefit them.
Some are really driving this agenda and really seeing the benefits.
Others don't see it as fitting their perception of how it should be done. We have to get them up to speed.'
An early example of this came when work began on the substructures. 'We weren't as engaged with the suppliers as we should have been and material would build up on site, ' says Black.
'Our biggest challenge is educating and working with suppliers and getting them to see the vision of the client and understand how it will drive their business.'
To this end, Black has a team of 25 who work with the teams on the site and their suppliers to help them develop logistics strategies for their specific areas of work.
'So rather than having a large, centralised organisation controlling and operating all the activity, we support the teams to do it themselves, ' he says. 'It is a huge learning experience for them and can only be beneficial for us as a client in the future.
'What we've seen by taking the pile cage and rebar cutting and bending off site is significant.
Productivity on site, in terms of getting jobs done according to programme, would usually be 5560%. We're hitting 80-85% and this is now exposing areas we need to work on which were not previously visible to us.'
For this, BAA is working with Laing O'Rourke and Strategic Project Solutions to use Project Flow with greater degrees of sophistication.
'Project Flow gives us reason analysis of why 15% is not happening, ' says Black. 'It shows that maybe there was an issue out on site meaning that the work couldn't be done, or maybe there was a design issue. However, it also shows that failures due to supplied materials have been significantly reduced.
With the heavy civils work now reaching a peak, Black sees the big challenge for the next 12 months as applying the learning gained to date to buildings.
'Buildings and civils are very different in logistical terms, ' Black argues. 'In civils, the volume of steel and concrete needed is huge, but the variety low.
'In buildings you see this volume-variety relationship reversing, the supply chains get very complicated and the type of transport will change - with a proliferation of white vans and notifiable loads carrying imported glass, aluminium and marble flooring replacing bulk aggregates and steels brought in by train.
'On site, the number of suppliers will increase, there will be even more demand for space, and more demand for slots at the entrance gate. That is the type of environment the project team is really starting to have to manage and that is the main thrust of our attention.'