Smart bridges, smart tunnels: Transforming wireless sensor networks from research prototypes into robust engineering infrastructure

Abstract

We instrumented large civil engineering infrastructure items, such as bridges and tunnels, with sensors that monitor their operational performance and deterioration. In so doing we discovered that commercial o erings of Wireless Sensor Networks (WSNs) are still geared towards research prototypes and are currently not yet mature for deployment in practical scenarios.We distill the experience gained during this three-year interdisciplinary project into speci c advice for researchers and developers. We discuss problems and solutions in a variety of areas including sensor hardware, radio propagation, node deployment, system security and data visualization. We also point out the problems that are still open and that the community needs to address to enable widespread adoption of WSNs outside the research lab. IntroductionLarge civil engineering infrastructure items such as bridges, highways, tunnels and water pipes are expected to last for decades or even centuries. Over the course of their lifetimes, these structures deteriorate and require timely maintenance in order to prevent further degradation that might lead to accidents, the need for replacement or, in the worst case, collapse. Traditionally, early detection of such deterioration is achieved by visual inspection, either during routine maintenance visits or when a maintenance team is sent to the site to investigate a known or suspected problem. But such inspections are time-consuming and costly and therefore infrequent. An alternative is to equip infrastructure with sensors that are permanently wired up to report back to a central system; but this solution is not adopted very extensively because of the di culty and cost of running data and power cables to each individual sensor in challenging environments such as a subway tunnel or a long suspension bridge.The purpose of our research project, which at the time of writing has been running for almost three years, is to develop a system for continuous monitoring of such infrastructure using wireless sensor networks which, compared to wired systems, are easier and cheaper to deploy and also o er the opportunity for straightforward expansion.How nice it would be if we could just go out and buy a commercial o the shelf (COTS) wireless sensor network (WSN) system and use it for monitoring our structures straight away. Unfortunately, though, the available commercial systems are typically only kits of building blocks and a non-trivial integration e ort is required, together with the development of any missing parts, before arriving at a complete and usable monitoring solution.This experience paper identi es some of the challenges and issues encountered when installing wireless sensor networks in the eld, with speci c but not exclusive reference to civil engineering deployments, and discusses how these challenges can be addressed. Inspired by the format of the instructive and well-presented paper by Barrenetxea et al. [2], which content-wise is largely complementary to ours, we share our experience in the form o...

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