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Noise and Vibration - Yonge North Subway Extension

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Key Findings

Construction Noise

  • The impact assessment conservatively assumed that all construction equipment would operate in a small work area closest to each sensitive receiver instead of being spread throughout a given site.
  • Without mitigation, construction sound levels are predicted to exceed construction noise criteria at many sensitive receptors* along the alignment. 
  • To reduce potential impacts, appropriate mitigation measures (see Potential Effects & Mitigation Measures) will be implemented in addition to the development and implementation of a construction noise management plan before construction begins.

Construction Vibration

  • The impact assessment employed a conservative approach, where construction equipment was assumed to operate at the edge of a given construction site, closest to sensitive receptors.
  • Without mitigation, there is the potential to exceed the vibration criteria at receptors located near (within approximately 9m of) the surface construction sites along the alignment.
  • Tunneling using the tunnel boring machines is not expected to exceed the construction vibration criteria.  Tunnelling support activities (such as the potential use of a temporary railway within the tunnels) has the potential to exceed the vibration criteria at some receptors located near the tunnels. 
  • The potential for exceedances will be reduced by implementing appropriate mitigation measures (see Potential Effects & Mitigation Measures) and through development and implementation of a plan to manage construction vibration before construction begins.

Operational Noise

  • The operational noise of the subway is predicted to meet the existing pre-project sound levels. Therefore, no mitigation is needed.
  • The subway vehicle passby noise is predicted to meet or be below the passby noise criteria at any sensitive receptor along the alignment. Therefore, no mitigation is needed.
  • With proven mitigation measures such as noise barriers, the sound levels from all stationary sources (including stations, ventilation equipment, traction power substations, bus terminals, and train storage facility) are predicted to meet or be lower than the applicable criteria at all assessed sensitive receptors along the alignment (see Potential Effects & Mitigation Measures for more details).

Operational Vibration

  • Using proven and readily available mitigation measures, ground-borne vibration and ground-borne noise from subway operations are predicted to meet or be lower than the applicable criteria at all sensitive receptors along the alignment (see Potential Effects & Mitigation Measures for more details).
  • As detailed design progresses, more detailed studies, including in-field testing, will be completed to define specific vibration control measures.

 

diagram Showing How Vibration Travels and Affects Residential Buildings

Figure 1: Figure Showing How Vibration Travels and Affects Residential Buildings (Royal Orchard Area)

Operational Noise and Vibration Criteria

Trains

  • The noise and vibration criteria for the trains are provided by protocols provided by the Ministry of the Environment, Conservation and Parks.
  • As there are no provincial requirements or standards for ground-borne noise, the criteria from the US Federal Transit Administration are used, similar to other recently completed transit projects. Noise and vibration mitigation will be investigated and implemented if a project is predicted to exceed any of the following criteria:

diagram

Stationary Facilities

  • The train storage facility (TSF) and facilities such as stations (which include ventilation equipment), traction power substations and bus terminals were assessed in accordance with the Ministry of Environment, Conservation and Parks, Environmental Noise Guideline - Stationary and Transportation Sources - Approval and Planning (NPC-300). Noise and vibration mitigation will be investigated and implemented if a project is predicted to exceed any of the following criteria:

diagram


Noise & Vibration Terminology

  • Ambient Noise and Vibration: The pre-project background sound and vibration levels. Used interchangeably with background or baseline sound and vibration levels.
  • dBA: Noise level adjusted to how humans experience different frequencies.
  • Air-borne noise: Noise transmitted by air.
  • Ground-borne noise: Noise generated by building/ structure components in response to ground vibration.
  • Ground-borne vibration: Vibration of building/ structure components in response to ground vibration.
  • Lpassby: Represents allowable noise level associated with a train passing by.
  • Vibration Velocity RMS, or Root Mean Square: Measure of vibration amplitude and an indication of vibration energy, also expressed as VdB.
  • Traction Power Substation: A facility that transforms the utility supply voltage for distribution to the trains.

Potential Effects & Mitigation Measures

Potential Effects:

Construction Noise and Vibration

  • Without mitigation, there is potential for noise criteria and vibration criteria exceedances at some receptors near the surface construction sites along the alignment.

Operational Noise and Vibration

  • Without mitigation, there is potential for stationary facilities noise criteria exceedances as well as exceedances of the ground-borne noise and vibration criteria at many receptors along the alignment.
  • There are no predicted exceedances of the air-borne noise criteria from train operations at receptors along the alignment.

Moveable point frogs

Figure 2: Moveable point frogs eliminate the gap between rails at crossovers, reducing the noise and vibration from trains passing over those crossovers

frog showing gaps between the rails

Figure 3: Standard crossover or frog showing gaps between the rails that generate additional noise and vibration

Mitigation Measures:

Construction Noise

  • Use equipment that meets the Provincial criteria in NPC-115.
  • Ensure equipment is kept in good working order and operate with effective muffling devices where required. Provide smooth surfaces for vehicles to travel throughout the construction zones to help reduce impulsive noises such as tailgate banging of dump trucks.
  • Develop construction staging plans that reduce noise at nearby sensitive receptors. This can include:
    • Maximizing the separating distance from stationary equipment (such as generators and compressors) to the extent feasible,
    • Selecting truck staging areas that are as far away from sensitive receptors as feasible,
    • Designing optimal truck routes that minimize on-site movement (especially reversing) and avoiding travel along the quieter residential streets
  • Schedule noisy activities during the daytime periods, where possible.
  • Consider and erect temporary noise barriers or acoustic enclosures around noisy equipment such as concrete pumps, compressors, or generators and around long-term construction zones (such as the launch shaft), as required.
  • Conduct real-time noise monitoring to identify sources of potential criteria exceedances and to implement additional mitigation measures to minimize the noise and vibration impacts, if required.
  • Develop a communications protocol to provide notifications to the community on upcoming noisy activities, nighttime construction and their duration, and address complaints in a timely manner.

Construction Vibration

  • Implement vibration isolation solutions such as resilient fasteners for the temporary tracks used by the temporary service locomotives during tunneling or use of rubber-tired service vehicles, as required.
  • Minimize the gaps between adjoining rail segments in the temporary tracks.
  • Conduct regular inspection and maintenance of the temporary tracks, service trains and railway cars to minimize noise and vibration during tunneling operations.
  • Schedule vibration intensive activities such as vibratory compaction during the daytime periods where possible.
  • Complete pre-construction condition surveys and conduct monitoring in accordance with City of Toronto Bylaw 514-2008 as required.
  • Maximize distance between equipment and sensitive receptors, where possible.
  • Select construction/maintenance methods and equipment with the least vibration impacts, where possible.
  • Operate construction equipment on lower vibration settings where available. 
  • Heavy equipment traveling over bumps or inconsistencies in the surface can generate higher vibration levels. Maintain smooth surfaces throughout construction zones to reduce vibration levels from such activities.

Operational Noise

  • Deploy vehicle and track technology and related maintenance measures.  These include regular wheel maintenance (to ensure smooth and round wheels) and rail grinding (which ensures smooth rails).
  • For the stations, traction power supply substations and portal structure, implement the following mitigation:
    • All tunnel ventilation fan systems are to be provided with silencers, as required, to minimize noise and comply with the criteria outlined in MECP’s noise guideline for stationary and transportation sources (NPC-300).
    • A 5.5m tall noise barrier at the Clark Station bus terminal, subject to further detailed design of the terminal.
  • For the train storage facility, implement the following mitigation:
    • A 5.5m tall noise barrier along the western extent of the train storage facility, subject to further detailed design of the TSF.
    • Implement quiet special trackwork such as moveable point frogs.
  • Select facility (stations, TPSS, and TSF) mechanical and electrical equipment to minimize sound levels and meet NPC-300 criteria.

Operational Vibration:

  • Implement mitigation measures such as floating slab track, ballast mats, resilient fasteners and moveable point frogs, subject to further detailed design and studies, such as in-field measurements of the soils ability to transmit vibration.
  • Implement regular vehicle and infrastructure maintenance such as rail grinding and wheel maintenance.

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