The REM and noise
From train to light rail
For residents living near the former Deux-Montagnes train line, the transition from train to light rail means changes in the sounds made by the system, with the removal of whistles announcing arrival at the station and the removal of level crossings and hence of alarms that sound when a train approaches. These audible warning mechanisms are no longer required, as the REM will travel on a dedicated, protected track, which will never cross cars or other road users. In addition, REM trains will be much shorter than the trains of the former Deux-Montagnes line, making each passage less intrusive and noisy.
What can create noise in the REM’s case?
While the REM’s rolling stock was designed to minimize rubbing, vibrations and noise, once the light rail is in operation, the sound may be audible. The noise will come from two main sources: the passage of REM cars and stationary sources.
The noise from the passage of cars may be caused by:
- Machinery (motor, ventilation, etc.) – When stopped or at low speed (entering and exiting the stations)
- Interaction between the wheels and the rails – Medium to high speed (in movement)
The noise produced by adding stationary sources may be caused by the:
- Systems in place at the stations (e.g. ventilation, heating/air conditioning) and the power supply
- Presence of bus terminals, parking lots or drop-off areas
Analysis of noise and impacts
Concretely, what does this mean for REM users and neighbours? Let’s discuss noise and its perception in time.
How is the noise impact calculated?
Unit of measurement
Since sound is perceived through the ears, it is difficult to assess objectively. The noise tolerance threshold is subjective and affected by the accumulation of auditory sensations during the day. The sound level in decibels provides a concrete idea of the situation, though. Sound intensity is measured in decibels or adjusted decibels (dB or dBA). The increase in sound follows a logarithmic scale. For example, an increase of 3 dBA is only slightly perceptible to the human ear, while an increase of 10 dBA is perceived as twice as loud as the initial noise level.
In the case of an increase, it is important to consider the initial level. For instance, an increase of 10 dBA in a location initially at 20 dBA will be less significant than an increase of 10 dBA in a different location initially at 80 dBA.
|0 dBA||40 dBA||60 dBA||80 dBA||140 dBA|
|Threshold of audible sound||Quiet room||Normal conversation||Conversation is difficult; very loud||Intolerable sound level (e.g. jet take-off at < 30 m)|
Known sounds in our environment and dBA levels
Analysis of the REM’s noise
The cumulative noise due to the passage of REM cars was modelled for 24 hours, at the limit of “sensitive receivers” meaning residential, recreational and institutional (e.g. schools, hospitals) properties along the entire route.
To assess the noise impact of the REM, a large number of inputs were considered:
Removal of exo train noise along the former Deux-Montagnes line
Addition of the REM’s noise, taking into consideration frequency and speed, structure elevation, route curves, etc.
Consideration of ambient noise, road traffic, topography, proximity to residential areas, etc. (current situation, before commissioning of the REM)
In the case of stationary infrastructure, individual stationary sources of noise are analyzed.
Noise impact of the REM
The noise impact of the REM may be imperceptible, meaning that the noise made by the passage of REM cars may fade away into existing ambient noise, such as highway noise. In some places, such as the South Shore and the West Island, the noise from REM cars disappears into the ambient noise of Highway 10 and Highway 40.
The noise impact of the passage of REM cars is considered significant when the difference between the current and the projected sound level of the REM in operation over 24 hours generates a moderate to strong impact based on the Ministère des Transports du Québec road noise policy.
For more information about significant impacts, consult the fact sheet here:
In all cases where it was identified that the REM’s noise would have a significant impact, the project includes measures to comply with government thresholds.
Mitigation measures implemented by the REM
Carried out with specialized equipment, this measure aims to reduce rail roughness, i.e. to "smooth" the track, in order to reduce the noise generated by contact between the wheel and the rail.
Dynamic absorbers are installed directly on the rails and are designed to reduce rail radiation. They therefore reduce the propagation of vibrations to the rail and the noise generated.
Installation of noise barriers
Noise barriers are installed wherever the modelling identified significant sound impacts along the route. The installation of these barriers has already begun in some sectors.
Is there a noise barrier near you?
If a significant noise impact has been identified near you, a noise barrier was included in the project. Discover where these barriers are located in the various sectors:
If you can’t find your sector in the maps, it’s because there are no noise barriers near you. If you want to know more about the impact of the REM’s noise near you, though, the decibel measurement is available in the full sound modelling for all the listed addresses.
Mitigation measures for stationary sources
Mitigation measures are also planned for stationary infrastructure, such as the installation of silencers and the construction of artificial obstacles such as barriers, that are integrated with the design of the infrastructure.
Monitoring in operation
Once the REM is in service, a sound monitoring program will be implemented to ensure that mitigation measures are effective and that noise levels correspond to the modelling. If the monitoring finds additional significant impacts, extra measures will be implemented.
Information on REM noise in operation
Noise from passing cars on the segment between L'Île-des-Sœurs and Griffintown
Full sound modelling
Detailed sound modelling was done to assess the anticipated ambient noise due to the passage of REM cars in operation. Consult the full sound modelling.