Railway and platform monitoring during construction
Authors: Sandra Kombouare, Steven Thurgood & the Oxygen agency
New monitoring methods
Gare de la Croix de Berny, RER B, Antony (92), FRANCE
October 2018 - July 2019
||Railway transport operator in Paris region|
||Construction company, subsidiary of Bouygues, expert in housing engineering, education, health, transport, industry and environment.|
|GEOFIT||Geospatial data acquisition and processing land and engineering surveying company.|
RATP enlisted construction company Brézillon to undertake demolition of a pedestrian bridge over a live railway, construction of a replacement underground passageway crossing beneath the tracks and the demolition and reconstruction of a building for passengers at the Croix de Berny station, near Paris, France.
Brézillon contracted the services of GEOFIT to complete land and engineering survey works for the scope of the project, including monitoring the stability of the railway track and platforms during the 9 month construction process.
GEOFIT were confident to meet the challenging technical standards of RATP, who as part of the construction project required assurance monitoring combining geodetic and geotechnical instrumentation. The instrumentation was detailed in the monitoring specification for the project.
The project specific solution
GEOFIT have experience in the use of new and advanced technologies, thus designing and operating hybrid instrumentation was a welcome challenge. They were awarded the contract to undertake the land and engineering surveying operations of the project, 80% of which were dedicated to the monitoring of the construction works at the station.
Mr Alexandre Toubois, Head of Infrastructures & Monitoring at GEOFIT and his team were tasked to monitor the railway track geometry, platforms, the surrounding infrastructure and the temporary works during the demolition and construction phases.
Using a combination of technologies, an automated monitoring solution was developed following consultation with the monitoring experts at Leica Geosystems France, combining Leica Nova TM50 total stations and WiSen wireless sensors.
Knowing the requirement for a rapid 2-minute reading frequency for specific assets, a hybrid monitoring solution was developed by combining continuously operating automated total stations (measuring 3D prisms non-stop) and a dynamic reading interval solution using WiSen sensors (tilt and crack gauges).
They installed arrays of monitoring sensors to the railway track, platforms and other structures (station buildings, overhead electrification support columns and existing structural cracks).
Hardware and Software
Data from these sensors was managed in a single interface (Leica GeoMoS Monitor) and made accessible to the client through the Leica GeoMoS Now! visualization platform.
Using these systems, a team of experts was able to obtain frequent and reliable observations under all conditions. The monitoring made it possible to follow precisely the effect of the construction on the railway tracks and associated structures. Wireless tilt sensors were utilized, measuring relative displacement data of the railway track for automated computation for rail geometry data (CANT & TWIST).
The total station prism monitoring provided absolute displacement data, validating the relative data and allowing for further railway geometry computations to be completed. In addition monitoring data regarding associated structures and settlement was computed using the information from the 3D prism observations. The Leica GeoMoS software suite enabled sensor control, data acquisition, calculations and event management. The software calculated deformation from the integrated solution in real time combining all data feeds into a single source. Users were able to configure individual element trigger values and alarm actions thus providing alerts when deformation exceed a specified threshold.
Using these instruments and their integration within the Leica GeoMoS software suite GEOFIT was able to meet the expectations of their client for reporting and alarming of any deformation detected with the assets.
GEOFIT was able to ensure the smooth running of the work by analysing the data collected and by informing the operator and the construction company of any change. This complete instrumentation & monitoring solution for the railway environment allowed the work to be carried out on time, without causing any inconvenience to station users. The monitoring not only ensured the 3rd party user safety, but also ensured the safety of the various stakeholders and construction operatives present at the site.
Clients Brézillon and RATP welcomed the implementation of this combined innovative solution using technologies installed and operated by GEOFIT, which allowed the work to be carried out securely with no delays.
For more information contact the monitoring solutions specialists at Leica Geosystems.