Colne Tidal Barrier is located on the Colne River estuary at Wivenhoe, Essex. The barrier is owned and operated by the Environment Agency (EA), the barrier provides a means of flood protection to the town and localities upstream of the gates.
Scroll for more
The gates are normally open and are closed during swells or periods of particularly high tides. The barrier is closed approximately twenty times per year; however due to weather changes there may be a requirement to operate the barrier in excess of fifty times per year. The barrier comprises two 16.9m long by 7.4m tall hydraulically operated mild steel mitre gates each weighing approximately 100 tonnes. The mitre gates are supported at the piers on pintle-and-gudgeon bearing assemblies. HS Carlsteel Engineering were contracted by Interserve Construction to undertake the manufacture, testing and installation of new lifting frames which would enable the gates to be lifted out of the water to undergo inspection and maintenence.
As part of the original design package for the gate system, a set of two Mitre gate Lifting Frame (MLF) assemblies were provided for the purposes of maintenance and inspection of the barrier gates. The frames provided a means of lifting the gates vertically out of their bearings using a system of hydraulic strand jacks mounted on slide carriages. Each gate is fitted with two lifting points, a single point positioned at each end of the gate. A pair of lifting frame assemblies is required to lift a single gate. Once a gate has been lifted out of the pintle-and-gudgeon bearings it can be moved away from the pier using hydraulic bottle jacks. The bottle jacks interface with the strand jack slide carriage and are reacted by shear blocks welded to the top beam of the lifting frames. The slide carriage arrangement affords a total lateral movement of 1000mm away from the pier.
The New lifting frames were required with a modified design to increase the lift height by 1000mm to aid the inspection and maintenance of the barrier. The basis of design was completed in accordance with BS 2573 Rules for the design of cranes, Parts 1 and 2 with the construction of the lifting frame being made from high grade carbon steel components with the exception of the slide rail carriages.
The lifting frames each weighing 31 tonnes were manufactured from S355J2+N sections generally comprising 356x406x393UC sections and S355 Z35 plates with a maximum sulphur content of 0.005 and up to 100mm thick in our workshops. They were inspectioned during fabrication by a third party (Sandberg Consulting Engineers) during February, March and April 2014 to verify the welding quality.
It was a legislative requirement as part of the Lifting Operations and Lifting Equipment Regulations [Ref. 6] and the Supply of Machinery (Safety) Regulations 2008 [Ref. 7] that all lifting equipment shall be thoroughly inspected prior to placing it into use. Over-load testing of a lifting structure constitutes a key part of the thorough inspection process. It was strongly recommended that all parts of the lifting frame assemblies for the Colne Barrier be over-load tested in accordance with LOLER regulations.
Two separate tests would be then undertaken by others in insitu \once the frames were installed:
A 127 tonne (1242kN) test performed with the carriage positioned at the gate lifting point.