Tunnels & Subways

Construction activities and the creation of new tunnels create vibrations that can impact nearby tunnels or subway systems.

Why Monitor Your Tunnel & Subway Project?

Construction activities that take place on the surface can create vibrations that have an adverse impact on tunnels or subway systems that lie beneath job sites. Similarly, the processes and equipment, such as blasting or tunnel boring machines (TBMs), used in the creation of new tunnels can cause damage to existing tunnel or subway systems. These activities create ground vibrations which travel through the ground away from the source. When vibration levels from the creation of a new tunnel are high enough, they can also damage roads, buildings or other structures above ground.

Similarly, when vibration levels from above ground construction or the construction of a new tunnel are high enough, rock or other material can become dislodged and fall on the tracks or road in the tunnel. In these cases, the traffic system may need to be shut down until the debris can be found and any damage is repaired. These damages can be costly and result in project delays.

Cars drive through city road tunnel

How Instantel Can Help

Monitoring systems from Instantel record vibration and air overpressure levels. Recorded data can be viewed almost immediately so you can adjust your activities before any concerns develop. Warnings and alarms can be triggered on pre-configured levels that you set, and these can be different for each job. Instantel’s monitoring system will alert you to any warnings or alarms through email or an audible or visual system on site. Sirens and lights can automatically be triggered when a warning or alarm has occurred. Notifications can also be sent to you or any party you choose. These notifications can be viewed on computers, laptops, tablets or smartphones and an historical record of the data can be maintained to protect you from claims and liability.

The Instantel system combines a Micromate® monitoring unit with a variety of sensors. Our monitoring systems can be quickly installed and easily configured. Cable lengths can be run up to 3250 feet so that the monitoring unit can be mounted and configured outside of the tunnel. If electromagnetic interference (EMI) is a concern, the Minimate Pro monitoring unit and sensors are shielded to prevent electrical noise.

Borehole Geophone


Triaxial Geophone

Sound Level Microphone

Borehole Geophone

Monitoring unit with four available channels: three channels for recording vibration on three planes and one channel for air overpressure or noise data. Records ground vibration in three planes: transverse, vertical and longitudinal. Available to meet ISEE, DIN and Swedish blasting standards. Class 1 Sound Level Microphone records noise (or sound) levels. The Sound Microphones meets the IEC 61672-1 standards. Lowered into a borehole. Records ground vibration in three planes: transverse, vertical and longitudinal. Available to meet ISEE, DIN and Swedish blasting standards.

Our system is scalable, as your monitoring needs change, sensors can be added or removed. If today you are monitoring vibration levels on a tunnel but tomorrow you need to monitor vibration and noise levels at a nearby business, simply add a Sound Level Microphone. You may also need to monitor underground structures like sewers or gas lines that are adjacent to the tunnel. When there is above ground access, a Borehole Geophone can be used with the Micromate monitoring unit. The Borehole Geophone is lowered into a borehole drilled near the structure and provides a more accurate measurement of the vibration level at the structure.

Aerial view of tunnel construction through city

How A Micromate Monitoring System Connects Using THOR and Vision Software Systems

Instantel’s monitoring systems can be installed permanently for the length of your project. Our equipment is designed to withstand long-term installations. By connecting a modem to the monitoring unit, recorded data can automatically be sent to your computer, server or to Vision, Instantel’s cloud-based data hosting solution. Using Instantel’s desktop software, THOR, the connected unit can be programmed remotely. Our scheduler lets you quickly program the days and time frames you would like to monitor. From your office, you can quickly program a unit, view battery and memory levels, retrieve events, perform updates and sensor checks, restart the unit or configure Auto Call Home settings.

Some transit authorities require 24 hour access to the recorded event data. Instantel monitoring units connected to a modem can automatically send event reports to Vision. Vision lets you share your event data automatically and it can be accessed 24/7 from any internet connected device. Instantel’s Histogram Combo recording mode lets you monitor the tunnel 24 hours a day and still get event reports when trigger levels are exceeded. The histogram event report will show you the peak vibration levels at set intervals throughout the day and any exceedances will be recorded as a waveform event. With Vision, you can also create customized reports and add in data from other sensors that may be onsite like strain gauges or concrete sensors.

Instantel's systems are designed to be configured remotely and record automatically. Our systems are designed, manufactured and calibrated by Instantel.