Caption: Repairs carried out to river bed beneath tower bridge . Repair work is being carried out in the bed of the river Thames adjoining Tower bridge , by the Port of London authority . The bed of the river at this point has been hollowed out by currents and large quantities of ballast are being dumped to fill the holes so that there shall be no danger of the foundations of the bridge being endangered . A dredger dumpings ballast beneath Tower Bridge to fill the holes beneath the bridge . 8 March 1932