Teams that collaborated successfully on the Shortlands box for CTRL have been reunited on a project in Kent.Gareth Beazant reports.
Engineering is renowned for its diversity. No two projects, no two days are the same. But on one project in north Kent, repetition is proving a good thing - not with materials or processes, but in team relationships.
The new £8M Milton and Kemsley distributor road will provide a direct connection to the A249 Grovehurst interchange for the stream of heavy trucks from the Kemsley Paper Mill that now rattle through Kemsley's winding village roads.
The 1.5 km single carriageway will also provide spur roads for future housing and employment developments. It will bridge the Sheerness to Sittingbourne rail line and an access road to a National Grid substation.
Funded by developer Kemsley Fields as part of a S278 Agreement with Kent County Council, the scheme is part of Thames Gateway Kent Partnership's redevelopment that seeks to regenerate the area from Dartford to the Isle of Sheppey. It is project managed for Kemsley Fields by CPM Consulting.
Principal contractor Geoffrey Osborne called on May Gurney Geotechnical for the piling subcontract.
'It's part of a growing relationship we have with Geoffrey Osborne, ' explains May Gurney southern area manager Steve Longdon.
'We worked together on the Shortlands Junction project in Bromley for the CTRL and it's a very good relationship. Here the project is similar as we're again involved with Network Rail.'
It is two years since the Shortlands Junction project (GE September 2002), but the latest scheme brings back memories of the 'big push in Bromley'.
May Gurney's site foreman Paul Mason says both his and the Osborne team have remained almost identical.
At Shortlands, the aim of the £65M scheme was to clear a pinch point on the Eurostar route. Work involved jacking a 70m long reinforced concrete box section tunnel and similar 18m long bridge box beneath a road, as well as contiguous piled wingwalls.
'It built a mutual understanding of the way both teams operate, ' Longdon says. 'We know how able we are and how able they are and vice versa. We both know each other's strengths and this really benefits the project.'
Although the rural Sheerness Railway can only dream of reaching speeds that will be achieved on CTRL, the same attention to detail is essential.
May Gurney will have to come within 6m of the railway while installing the 118 piles for the bridge structure. 'We have had to work vigorously on method statements, ' Longdon explains.
'Detailed method statements, risk assessments and lift plans are prepared for each section covering the positions and orientations of the piling rig and attendant crawler crane used to place the pile reinforcement cages.'
Detailed method statements have also avoided the need for any railway possessions during the piling work. 'We are experienced in working in close proximity to the railways, not only through our May Gurney Rail business but also on projects like this.'
Foundation structures for the bridge are divided into three elements: the east pier and east wingwall; the central pier; and the west pier and west wingwall.
The east piers and west piers each require 19, 900mm diameter CFA piles with 27, 750mm piles for each wingwalls. On the central pier two rows of 13, 750mm diameter piles are needed. Piles are being installed by the firm's Llamada P150 TT machine.
The central pier is between the access road to the National Grid substation and the Sittingbourne to Sheerness Railway. This access has to be kept clear at all times, so when the piling rig sits on this road to pile the centre part of the bridge, a traffic diversion will put in place behind it.
CFA piles will reach 19.5m at their deepest, going through about 5.5m of clay, Woolwich Formation sand to 13m and founding in the Upnor Formation.
Reinforcement of all the cages is reduced halfway down and where possible May Gurney has ensured that reinforcement cages were fabricated in one piece.
Crushed concrete is being used as the piling mat following the recent wet spell in the area.
The five-week piling project began in late January. The engineer is Babtie Group while WSP Group designed the bridge.