Brunel's Other BridgeBob Watkin's drawings for ground investigation work adjacent to the Brunel Swivel Bridge
January 2016: Investigation of the ground around the Swivel Bridge, including a cable percussion borehole, one day's trial pitting at three (or possibly four locations if time permits) up to 3.5m mbgl, with insitu geotechnical sampling, all supervised by an engineering geologist, and an archaeologist.The proposed locations of the single borehole and trial pits are shown on the plans.
Geocon Site Investigations Ltd of Almondsbury is the chosen contractor, and have been made aware of the Plimsoll Swing Bridge and the need to take down the drilling rig before bridge swings.
particular hazards which have already been identified:
- the presence of the public in the vicinity;
- the unprotected edge of the Entrance Lock to the north of the bridge;
- the 3T vehicle-weight limit from Brunel Lock Road to the bridge site;
- the risk of flooding at extreme high tides;
- risk of bridge movement and distress if the ground adjacent to timber blocks, on which the bridge is presently supported, is disturbed;
- the low headroom under the Plimsoll Swingbridge when it swings over the whole site potentially one hour before to three hours after high tide twice per day.
Contact Bob Watkins
 1:200 showing baseline, survey stations and trial pits |
 1:100 trial pit 4 |
 1:100 service station on abutment |
 1:100 trial pits 1 to 3 |