Botley Road Bridge

The oxford station redevelopment project will include the Demolition of the existing Botley Road under bridge and footbridge to allow for the reconstruction of a new under bridge, inclusive of two additional rail spans.

This scheme required the construction of 32 Number 1050mm diameter piles to depths of up to 40m to be constructed either side of the existing Western and Eastern rail span bridge.

Typically piling rigs with an operating weights of at least 80 tones would usually be required to construct piles of this diameter and depth but with the restricted location of these works adjacent to the live rail line in the width of a dual carriageway this was not a favorable option.

In addition to the permanent works piles, Martello also installed a 1050mm 40m deep sacrificial test pile with an Osterberg-Cell to validate the performance of the permanent works piles.

Martello employed one our MP4000 series rigs using the Martello technique to bore the 1050mm piles to depths of up to 40m. The 20t operating weight with a small footprint of 6m x 2.4m and an operating height lower than the rail level allowed the rig to easily manoeuvre under the railway bridge aiding sequencing and constructability. 

The installation of the cages posed yet another challenge as the design dictated heavy reinforcement giving individual weight of up to 13t per pile.

With these cage weights two Sennebogen 673 telescopic crawler crane were used either side of the rail bridge to install reinforcement and tremie piles apart from 8 number piles as these were suitably close to the live railway that would prevent ALO working. The MP4000 series rig was able to operate at a height that was below rail level and enabled these piles to be bored and tremmied by the rig during day shifts ALO working with the cage reinforcement installed by the attendant crane in suitable line blocks or weekend possessions.

Within the programme of works there was the requirement to installed a prelim test pile, however due to the tight working area of the site and the need to keep the overall footprint of the test as tight as possible for follow on trades Martello engaged Fugro who are the specialists of the Osterberg (O-Cell). This test negated the need for reaction anchors or a large top down grillage and therefore was the preferred solution for the client.