Bassett Convergence SystemThe Bassett convergence system is used to monitor transit tunnels for potential damage from nearby construction activities. OperationThe BCS monitors movement of reference points that are mounted on the tunnel lining. The points are aligned to a plane that is normal to the axis of the tunnel. A system of articulated arms links each reference point to the next, and forms a series of virtual triangles. A tilt sensor is mounted on each arm. Spatial displacement of the reference points moves the arms and results in changed tilt readings.
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![]() The system can operate in near-real time. A complete set of tilt readings can be recorded in about five seconds, and the remote computer can update the graphic display in just a few seconds more. |
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AdvantagesLow Profile Design![]() The BCS is designed specifically for tunnels. The system fits close to the tunnel wall and does not interfere with normal traffic. Arms can be shaped to provide extra clearance or to bypass obstructions. No Optical ComponentsUnlike optical systems, the BCS has no line-of-sight requirements and can be installed around corners. In addition, the BCS is not affected by changes in the refractive index of air caused by passage of a train. Robust and ReliableThe BCS easily accommodates normal tunnel traffic, vibration, temperature changes, and electro-magnetic emissions. Near Real-time DataThe BCS can complete a survey of a tunnel section, process the readings, and generate displacement data in seconds. This is important for the protection of trains and passengers when nearby construction may damage the tunnel. |
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For more informationPlease download the datasheet and manual for the BCS Tunnel Monitor. You may also be interested in a description of BCSWin software. (Not for Windoes™ Vista or Windows™ 7) These documents can be viewed and printed with Adobe Acrobat Reader. |

