The Rise of the Concrete Dragon; a Bridge Too Far

I have been involved with research investigating the use of GPS and GNSS for measuring the deflections of bridges for almost 20 years. This includes measuring the size of the movements, as well as measuring the frequencies of the movements. These are characteristic of the individual bridges, and this approach is thought to be a useful tool for structural health monitoring. This research started on the Humber Bridge on the 7th March 1996, whereby I placed an Ashtech ZXII RTK GPS unit on the Humber Bridge’s mid-span, and gathered some data. The results showed that noticeable movements were measured. This work developed into being able to measure the frequencies of the movements, as GPS has a very precise time associated with the carrier phase and pseudorange data. At the time, the output was at a rate of 1Hz, but today receivers are capable of data output at 10Hz, 20Hz and even 100Hz. This work has expended over the years to include such deflection monitoring of bridges including the Millennium Bridge in London, the Forth Road Bridge, the Severn Suspension Bridge and the Seohae Grand Bridge, Korea, a cable stayed bridge that connects Kyeonggi-do Pyeongtaek-si Poseoung-myun Naegi-ri to Choongcheongnam-do Dangjin-gun Songak-myun Bokwoo. These surveys have expanded to having up to 9 GPS/GLONASS receivers on the Severn Bridge gathering data at up to 20 Hz over a continuous period of 4 days.