July 01, 2010-- A landmark ground penetrating radar contract requires Fugro to survey 81,000 kilometres of the California Department of Transportation (Caltrans) road network and is the latest success story for the Fugro Transportation Infrastructure Group. The three-year, multi-million dollar project began in early 2010 and is the largest of its type ever undertaken.
Caltrans’ plans for managing their network rely on gaining a better understanding of the materials below the road surface. Most drivers focus on the smoothness and quality of the road surface. Highway engineers recognise that it is what lies below that can have the most impact on performance and durability. To keep the network in good shape, and to get the most from every maintenance dollar spent, Caltrans needs to know how thick their roads are, what materials are below the surface and where the major changes in construction occur. This information will contribute to cost-effective long-term prioritisation of resources.
Ground Penetrating Radar (GPR) pavement inspection can provide crucial data on pavement structure and condition including layer thickness and type, bond between layers, and mapping the presence of voids and moisture within and below the pavement structure. The non-contacting GPR equipment used by Fugro is operated at traffic speed, which is a big attraction to highways authorities because it causes less disruption to the road user. It also causes less damage to the road than the alternative approach of taking a large number of core samples.
Most GPR road surveys use either an air-launched horn or a ground coupled antenna. In order to meet the demanding requirements of the Caltrans specifications, Fugro’s ARAN data collection vehicle is equipped with both systems. The high resolution horn antenna, attached to the rear of the vehicle, scans the shallower depths, to detect thin layers and to enable calculation of material velocities for highly accurate results. A pod containing lower frequency antenna is hung below the vehicle to scan as deep as two metres. Whilst radar clearly offers a comprehensive range of data it cannot be used in isolation. Some pavement cores are required to confirm material type and calibrate thickness measurements. By targeting the cores from an assessment of the radar data it is possible to minimise the core number and maximise their value. Video log imagery will record a broad range of highway assets. This imagery provides useful process information on the surface condition of the pavement and construction changes.
This project brings together Fugro West Inc., Fugro Roadware Inc. and Fugro Aperio, combining their unique expertise in data collection and analysis. The team created a new process flow, to locate and process core results, so they could be precisely positioned in the GPR data stream, reducing the “relocation errors” that are a common problem in GPR analysis. Systems were adapted to fully synchronize GPR data to be tagged with GPS coordinates. Roadware also modified its new processing database, Roadware Management Suite, so that events such as construction segments could be automatically applied to the new surveyed data.
With survey and processing well underway David Lowe, Managing Director, Fugro Roadware, commented ‘Fugro is proud to be working with Caltrans on such an advanced project as this. The savings the State of California will make in reduced maintenance costs, through improved predictability of pavement performance, will enable Caltrans to target funds and investments where they are most needed and will make the greatest impact.’
For information regarding Fugro Roadware contact: Jenn Boyce Email Contact +1 905 567 2874
For information regarding the Fugro group visit: www.fugro.com