As part of Crossrail’s wider overground infrastructure programme, RMD Kwikform’s specialist solution accommodated the four live railway lines adjacent to the site, and adhered to Carillion’s focus of “health & safety and build-ability”. RMD Kwikform’s engineering capabilities were recognised by the British Construction Industry Awards, as highly commended in the temporary works category.
Modelling the traveller
Due to the nature of the project, the traveller design developed throughout the initial phases of the project. In order to get the required space between the track and traveller screen, Engineering Manager Ian Hawkesford, created the solution on Master Series, a frame analysis programme. This enabled the engineering team to assess the various pressures from passing trains on the shutter, and determine whether the size and capabilities of the traveller was fit for purpose.
One of the first aspects of the design that changed was the blind tie application. Initially we thought about putting a captive tie plate on the shutter and simply wire the wing nut, but due to prohibited space behind the shutter, the site operatives would have been feeding the tie through from the other side of the rebar cage. There would have been no way of knowing if the tie was engaged. Such a small part of the overall system, but changes like this became very significant to the overall innovation and the final design.
Striking the Formwork Panels
RMD Kwikform utilised a similar kind of shuttle design previously used on the Guardsmill Traveller, which used an overhead beam and a trolley on the lower flange. This allowed the shutter to be pulled away from the wall. The swing movement enables the site operatives to retract the shutter back 600 – 700 millimetres, which allowed for sufficient space for cleaning and oiling in preparation for the next concrete pour.
To construct the wall closest to the track, we found that there simply wasn’t enough space to swing the shutter forward. We realised that the shutter was constrained due to the beam that ran side-to-side above the wall, so we introduced another beam than ran parallel, which enabled the site team to crack the shutter and travel it sideways instead of forwards.
The wheels are an innovation we’ve used on several shutters in the past, including the Guardsmill Traveller. The wheels have the capabilities to move slightly on its axil, allowing for extra space to crack shutters and move them.
Also utilised on the Tyne Tunnel traveller was the hand turfer; this clamped onto the rails and pulled the system along.
It’s crucial to refer to previous projects when engineering a solution; we tend to find that the greatest of innovations and techniques are often the most simple. Both of these methods work effectively and efficiently, and its something RMD Kwikform will continue to utilise moving forward.
Making the most of the kit
In total, there were three different types of wall being constructed. It was important that we minimised the amount of kit being delivered to site, and due to the nature of our kit, it can be broken down and used in variety of ways.
The Superslim Soldiers and the Megashor components are ‘off the shelf’ items; they are sustainable, therefore we can reuse them wherever possible, particularly when the programme time dictates it. We were able to minimise the number of deliveries to and from site, and get maximum utilisation of all equipment, for instance, an 1800 Megashor component can be built out of two 900 Megashor components. It’s a very simple process that has economical and timesaving benefits.