Retention Sockets, STAKKAbox

During the redevelopment of a Pelican crossing in Twickenham, the client, Transport for London replaced old access chambers with STAKKAbox™ Modula.  

Once the civils’ contractor, FN Conway had completed the excavation, a concrete base was laid above the existing services and around a drainage duct for the STAKKAbox™ to be installed upon. With the base established the first section of the chamber, a pre-drilled access section, was positioned. Alongside the chamber a NAL Retention Socket with a Duckfoot Bend base was also installed to house a traffic signal pole. At this stage of the installation the Retention Socket was connected with ducting to the access section of the STAKKAbox™, simplifying the cabling of the traffic signal poles at a later date. 

A second access section was stacked onto the first for further incoming ducts, followed by a riser section for the third layer of the chamber.

To accommodate the positioning of two ducts both the second and third sections had to be drilled where the sections meet. This was easily achieved on-site with a hole cutter. The fourth and final riser section was then stacked, however due to the existing services the overall height exceeded the finished surface level. This issue was easily overcome by measuring the height difference and removing it with a circular saw. With the final section in place the ductile iron cover and frame was installed. By opting for the STAKKAbox™ Modula the installation was significantly quicker than a traditional brick-built chamber or liner chamber.