Joao Boavida, Adriano Oliveira, Bruno Santos: Precise Long Tunnel Survey using the RIEGL VMX-250 Mobile Laser Scanning System 04.04.2012
Artescan 3D Scanning, Portugal, www.artescan.net, has been using the RIEGL VMX-250 since July 2010 in diverse scenarios, especially where data acquisition productivity is pertinent. In this presentation, a long tunnel survey project will be described.
Spain has the longest high speed trail network in Europe. Recently, two parallel 25 km long tunnels were built and an accurate 3D survey was demanded by the Spanish authorities. Artescan accomplished this survey using the RIEGL VMX-250. The integrated INS-GNSS is specified for 1 minute GPS outages; however, in this case, each survey project was realized with approximately 1 hour of total GPS outage in the mobile receiver. An absolute accuracy of 2 cm was achieved by using a combination of well acquired exterior GPS positioning, INS and odometer measures inside the tunnel and use of control points. For trajectory adjustment, RiProcess powerful tools were successfully used.
Tunnels for transport have existed for centuries. They have been developed both in urban environments for mass traffic transports and in interurban environments mainly to cross mountains, both for roads and railways. The recent worldwide development of high speed railway lines has stimulated the construction of a large amount of new tunnels. These tunnels are longer and deeper, especially in mountainous regions, where base tunnels need to be built in order to obtain railway lines with minimum gradients connected with the valley level. Surveying represents an important role within these tunnels’ lifecycles by applying different technologies and methodologies, for different purposes, from the construction of new ones to the monitoring of old ones. Several tunnel surveying technologies are well known and documented. Mobile Laser Scanning, in spite of being relatively new, has already had several reference projects that are normally presented as application examples; very long tunnels have not been a part of those applications.
This paper will describe a very long tunnel survey project by using RIEGL’s VMX-250 Mobile Laser Scanning and a specific methodology developed to answer this challenge.