The engine room

These diesel rotary generators, recently installed in 30 The South Colonnade, provide emergency power back-up in the event of a mains power failure

Canary Wharf Contractors’ design management team have worked on some of the most demanding projects ever built in the UK. They push the boundaries further on every scheme to improve quality and build time. As new projects come up, they also have a head-start because of the knowledge accumulated on earlier high rises.

CWC structural design manager John Crack explains: “Rather than starting with a blank sheet of paper, we issue a set of design guidelines and outline specifications to the design team so, although no two projects are the same, we can get the detailed design moving in the right direction very quickly.

It’s the same with the consultants that CWC commissions, says electrical design manager Paul Mutti. “Even though we don’t use the same consultants for every project, a lot of them have worked for us on a number of occasions and they carry that learning across as well. Therefore, the learning process goes that much quicker and easier. We all know what’s expected from each other and that’s probably the key to building as quickly and efficiently as we do.”

Mutti and Crack previously worked for consultants. They know the importance of setting a good brief and reviewing the consultants’ designs while also considering the tenant’s requirements. Mutti says: “We are not there to judge our consultants and contractors. We are part of the team and we work with them. It’s a relationship from which, hopefully, everyone benefits.”

Crack says: “The structural side is very much at the front end on any building and the design of the structure is where significant cost is either built in or taken out, particularly if you can co-ordinate well with the services design. There will always be late changes to the services, which will have a knock-on effect on the structure. If you can iron out some of those problems, you can make the process go more smoothly.”

Warnings from history

Mutti agrees. “We know from previous experience what the pitfalls are. We have some fairly generic solutions based on previous buildings and we start with those and massage them to suit a particular project.”

Experience has taught Mutti about the problems of installing transformers and trained Crack to avoid large, rolled-steel columns. Mutti says: “One of the problems we found was that noise and vibration generated by the transformers was being transferred to the office floor below. Now, we fit anti-vibration mountings under the transformers and have flexible connections between the transformers and the switchboards.”

We issue design guidelines and outline specs to the design team so we can get detailed design moving in the right direction very quickly

John Crack

Crack adds: “Some of the steel column sections are so large that you can get a ‘hockey stick effect’ during rolling where the ends are distorted even though they are within manufacturing tolerance. That can cause a lot of problems during erection.

“Now, we generally make the large sections out of steel plate because we can get better tolerances and reduce erection time. It also means that we remove the dependency on British Steel rollings, where you may have to wait three months to get a particular section size unless it’s pre-ordered.”

Settling for the best

Another potential problem that CWC puts a lot of effort into minimising is the effect of differences in settlement rates between concrete and steel. Crack explains: “Steel columns squat almost instantaneously under load whereas creep means the concrete cores settle at a slower rate.” This leads to difficulties creating horizontal floors and ceilings between the concrete cores in the centre of the building and steel at the perimeter.

“It is more of an art than a science, but we have built up a great deal of experience on many buildings and work well with our contractors and consultants to minimise the effects,” says Crack. “You have to have an understanding of how the building tolerances accumulate and also have an understanding of what is most critical in the finished building. A 10 mm discrepancy in the floor-to-ceiling height is not important, but a discrepancy within the underfloor zone might mean it’s impossible to get all the services in.”

Mutti says the biggest change since the late 1980s is the amount of services that are required. Duplication is vital to ensure a tenant’s business doesn’t stop if there is a mechanical or electrical failure. To handle the demand for more highly serviced buildings, the size of plant rooms has grown dramatically: some are 100 × 60 m.

He continues: “More plant means increased loads and both have an enormous impact on design so we spend an inordinate amount of time up front with the building user, making sure we understand what their requirements are and then making sure our design consultants incorporate the requirements in the design.

“No other developer contractor has this sort of resource in house – I’d like to think that we add significant value by riding shotgun on the design at the critical stages of the project. We definitely build faster as a result.”