Ground penetrating radar and ground conductivity investigation of the fissuring of the A690 in Houghton-le-Spring

This report introduces the results of a geophysical survey using ground-penetrating radar (GPR)and ground conductivity methods to investigate the nature of fissuring observed in Houghton Cut, Tyne & Wear. The survey on the northbound carriageway of the A690 mapped the locationof a known fissure and described the nature of this feature to a depth of 3m. A suspected manmade feature (pipeline or other utility) was noted close to the known feature, as identified by ground conductivity measurements. Data interpretation was aided by the use of 3D radar data. The southbound carriageway was found to yield no useful data. A full investigation of Houghton Hill highlighted two major fissures that had surface expressions. These features were imaged to a depth of 7m and were mapped laterally up to 50m further than their surface expression. Three other smaller fissures were observed. A final linear feature was identified, but is suspected to be manmade (either a utility or drainage pipe). This work was partly funded by Sunderland City Council.