Letter Decision No. LET-R-151-2009

October 8, 2009

Complaint by Glenn Stalker on behalf of the West Toronto Diamond Community Group against Metrolinx, operating as GO Transit, pursuant to section 95.3 of the Canada Transportation Act, S.C., 1996, c. 10, as amended

File No.: 

Introduction and issue


On June 9, 2009, the West Toronto Diamond Community Group (WTDCG) filed a complaint with the Canadian Transportation Agency (Agency) pursuant to section 95.3 of the Canada Transportation Act (CTA) against "GO Transit's Joint Venture with Canadian National" regarding noise and vibration arising from the construction of the West Toronto Diamond Grade Separation (the project).

Although the WTDCG included the Canadian National Railway Company (CN) as a respondent to its complaint, the Agency, on July 28, 2009, in Decision No. LET-R-124-2009, determined that CN was not a proper respondent to the complaint in light of the recent sale of the railway line by CN to GO Transit. GO Transit is now known as Metrolinx, operating as GO Transit (GO Transit).

The WTDCG was created as local citizens began reacting to the noise and vibration caused by the project. It works to represent the broader interests and concerns of the community in negotiations with GO Transit and in consultations with political representatives. The federal Member of Parliament and the City of Toronto both made submissions supporting the WTDCG complaint. The WTDCG met with GO Transit several times in the winter and spring of 2009 to try to resolve the community's concerns about the noise and vibration caused by pile-driving activities at the project.

The WTDCG complains that pile-driving activities have resulted in undue exposure to excessive noise hundreds of metres from the construction site as well as exposure to ongoing vibration that shake floors and walls within 100m of the construction site, with every diesel hammer impact - often as frequent as every two or three seconds.


The issue to be determined by the Agency is whether GO Transit is meeting its obligation under section 95.1 of the CTA to only cause such noise and vibration as is reasonable, taking into account its operational requirements and the local area. If the Agency finds that GO Transit is causing more noise and vibration than is reasonable, the Agency must then determine what measures should be taken to ensure compliance with this obligation.


This background is based on the parties' submissions.

The West Toronto Diamond is the junction point of five railway subdivisions: the Canadian Pacific Railway Company (CP) Galt, North Toronto, and Mactier Subdivisions, and the GO Transit Weston and Lower Galt Subdivisions. The project involves the construction of a new rail-rail grade separation that will eliminate all six diamonds, and also a grade separation of the Old Weston Road - Weston Subdivision level crossing. The grade separation will extend approximately one kilometre in length and involves lowering the Weston Subdivision by up to 11m so it passes under the CP tracks.

GO Transit is installing a total of 2,388 interlocking steel pipe piles to a maximum depth of 22m to form both the outer and centre walls of the portion of the depressed corridor. These steel pipe piles are installed with impact hammers and/or vibratory hammers (definitions in Appendix 1) and will later be filled with reinforced concrete with horizontal struts at the top and a solid reinforced concrete slab floor. Installation of the pipe piles for this project began in January 2009 and is currently forecast to extend until June 2010. GO Transit reports that the extended date of completion is, in part, due to a shortage of piles which will result in periods of inactivity while the contractor waits for more materials.

The project is located within a constrained rail corridor with unique soil and water table conditions. It is within the urban area known as the West Toronto Junction which is one of the oldest parts of the city of Toronto. It is a densely populated urban environment with a mix of residential, commercial and industrial uses. Most of the buildings located nearest the project comprise the oldest housing stock within the wider neighbourhood. Many buildings were constructed in the late 1880's and may not meet current building standards or railway set back standards. The building housing the National Rubberized Tire Company (NRT) is a mere 2m from the railway right of way where construction is taking place.

Positions of the parties

General submissions

The WTDCG, supported by the City of Toronto, complains that residents have been exposed to excessive noise and vibration from the project which has resulted in physical harm, financial harm, mental and emotional harm and damage to well-being and community life.

The WTDCG submitted a petition signed by 288 residents as well as 88 statements from local residents who have been affected by the noise. Many complain that they are unable to open windows in their houses due to the constant noise. The impact of this is more noticeable during the summer months as many of these older homes do not have air conditioning. Many people state that the noise makes working from home difficult as their thought process is disrupted, they cannot concentrate, and they are unable to carry on conversations with clients even over the phone.

Other residents complain that the only means of dealing with the disturbance is to leave the house which usually means spending more money at restaurants and coffee shops. Others say that walking, biking and generally being outside is unpleasant and they cannot spend time in their yard or neighbourhood.

Some residents who work outside the home advise that they are in a bad mood when they get to work in the morning. Many residents also state that they suffer from headaches from exposure to the constant noise and others who work at night state that they cannot sleep during the day, even with the windows closed, and the noise is affecting their physical and mental health and their ability to concentrate at work.

Some residents have tried playing loud music, wearing noise cancelling headphones and sleeping with headphones on, but they maintain that none of this works. They state that the result is that they are sleep deprived, have difficulty concentrating, and feel exhausted all of the time and that they experience an overwhelming sense of malaise.

According to the residents, the noise and vibration are extremely invasive to their home and family life. One resident complains that the current noise feels like a war zone with constant shelling going on. Another complains that two days notice was given by GO Transit for round the clock work on weekends and asserts that this is unacceptable.

In addition to the noise, the WTDCG states that vibration from the project have resulted in tiles falling off walls, cracks in foundations, water in basements, wall and ceiling cracks, and household effects falling off shelves. A number of residents complain that they have had to take items off of walls to protect them, to put protective materials between china so the items don't rattle and to put tape on windows to stop the vibration.

GO Transit submits that the work involved at this location is part of its expansion of the current passenger rail network to address the steady increase in transit ridership within the Greater Toronto Area. According to GO Transit, the rail corridors that pass through the West Toronto Junction are heavily used by CN and CP freight trains, VIA Rail Canada Inc. intercity passenger trains and GO Transit commuter trains carrying over 43,000 passengers per day. GO Transit advises that grade separating the diamonds will eliminate conflicts between trains on intersecting routes, improve on-time performance and reduce travel time. GO Transit asserts that although current railway operations will be maintained, the project is a prerequisite for future commuter rail service expansion which will in turn help alleviate congestion on city roads and highways.

GO Transit also points out that the project fulfilled the requirements of both provincial and federal environmental assessments (EA). A report filed by GO Transit as part of the EA process indicates that the project is situated within the physiographic region known as the Iroquois Plain which is the bottom of the former glacial Lake Iroquois. The top 3m is comprised of extensive sand and gravel deposits underlain by fine grained clay and silt to depths of 7m. Beneath this, to a depth of 20m, is non-plastic silt and sand with 15 to 25 percent water content, followed by a 10m layer of boulder clay. Bedrock is found at approximately 30m below the surface. The report shows the water table in this region to be as high as 4.3m below ground level and that the combined soil and water conditions play a key role in the selection of a permanent structure.

GO Transit reviewed alternatives for the construction of the project and concluded that the tunnel option was preferred over a raised grade-separation due to the length of the project and unobtrusiveness of the final design. GO Transit also considered several different methods for constructing the tunnel walls which included: conventional piles and lagging walls which did not provide necessary resistance to water infiltration; sheet pile walls which did not provide the structural strength to support the deep excavation; reinforced concrete walls which did not allow for sufficient space; concrete slurry walls which would not set properly due to vibration from passing trains and could not be used below the water table; and, concrete caisson pile walls which would not support the weight of the train bridges and may allow water infiltration. GO Transit determined that the use of interlocking steel pipe pile walls is the best method given the required structural strength, water resistance, and space limitations.

GO Transit indicates that 2,388 steel pipe piles are required and that they can only be installed by driving them into the ground with impact and/or vibratory hammers as installation through auguring is not possible due to the soil and water table conditions. An additional 1,515 concrete caisson piles, installed through an auguring process, will be used in areas where piles are above the water table. GO Transit indicates that by using pipe piles only where necessary, the noise disruption is reduced.

GO Transit asserts that there are three types of hammers that can be used to install the steel pipe piles: diesel impact hammers, vibratory hammers and "silent" hammers, known as Giken hammers. While GO Transit's experience using a vibratory hammer and proposed use of the Giken hammer will be reviewed in the mitigative measures section below, GO Transit's latest submission indicates that it has been using three impact hammers which it believes are the fastest, most effective and reliable means of installing piles. GO Transit asserts that they provide a high level of accuracy, which is very important on this project as the corridor is very constrained, and strict tolerances are required to maintain standard railway clearances. GO Transit states that the drawback of this technology is the noise it creates.

Submissions on noise measurements

For ease of reference, definitions of dB, dBC, dBA, dBAi, dBA (Leq) and "equivalent sound exposure" are included in Appendix 1.

GO Transit and the WTDCG, as well as the City of Toronto, have taken noise measurements at the project site at different times since construction began.

GO Transit submitted various reports provided by Golder Associates with respect to noise measurements. In a report dated February 9, 2009, it is indicated that the noise levels reported are energy averaged levels over a period of time and do not directly represent the peak impulse noise levels resulting from the pile-driving activities. GO Transit also submitted noise measurements taken before the construction began to establish existing background noise levels. The average daytime levels at that time were submitted to be in the range of 61.7 to 74.3 dBA (Leq).

The WTDCG conducted noise readings on March 19, 2009 at six locations in the project area: behind 78 Osler Street, at the corner of Osler Street and Cariboo Street, at the western end of Cariboo Street, at two locations on St. Rita's elementary school playground, and at 1 Hook Avenue. These tests indicated that noise levels peaked at 102dB but were sustained at between 87 to 94dB. Recordings at a seventh location, north of Cariboo Street, measured 74dB but the WTDCG claims that some of the buildings provided buffers and as the project moves north the noise levels will likely increase.

In April 2009, tests taken by the WTDCG at Lindner Avenue, 100m from the noise source, recorded peak noise levels at 99dBC, but the WTDCG noted that there were residences between the testing site and the pile-driving activities and that the residents were likely subject to even higher noise levels. The WTDCG also took tests at Old Weston Road and Junction Road which produced constant levels of 96dB. The WTDCG submitted tests taken on June 9, 2009 on Cariboo Avenue, 70m from the source, which indicated constant noise levels at 97dBC.

GO Transit indicated that, on May 6, 2009, noise measurements from the impact hammers were recorded from locations 45m and 15m away from the source, to be between 101dBA and 120dBA, respectively with no mitigative measures in place. On June 12, 2009, after GO Transit had installed shrouds and rubberized chasers in an attempt to mitigate the noise levels, the noise from the impact hammers was recorded by GO Transit from the same distances to be between 96dBAi and 107dBAi.

GO Transit also submitted noise data from the vibratory hammer reflecting noise levels ranging from 91dBA at 15m from the source to 78dBA at 45m from the source.

The City of Toronto undertook daytime noise measurements on August 10 and 11, 2009, at five locations around the project area: at 1 Hook Avenue, 76 Osler Street, 25 Cariboo Avenue, 7 Miller Street, and 196 Old Weston Road. The tests indicated noise levels of up to 105dBA. The level of "equivalent sound exposure" measured between 74dBA and 89dBA.

All three parties recorded noise levels using different measurement methods. GO Transit stated that the WTDCG readings were not taken with the correct equipment and the WTDCG stated that GO Transit's readings were averaged and did not reflect the actual impulse noise.

GO Transit submits that the distance from the pile-driving affects the noise readings and moving the noise measurements from 15m to 35m from the source reduces the noise levels by 8dB. GO Transit also submitted noise measurements taken at various distances from the source of the noise, asserting that measurements taken at 35m from the source are indicative of the worst case scenario that any resident would encounter in this area. Therefore, GO Transit states that although it has recorded sound levels of up to 120dBA at 15 m, residents would not be subjected to this level of noise as no one is located 15m from the actual source of the noise.

GO Transit states that the sound levels taken at 35m were between 97dBA and 108dBA. To provide context for the noise measurements, GO Transit compared 100dB to a gas lawnmower and 110dB to a jet aircraft flying at 300m.

The City of Toronto noted that subsection 139(6) of Ontario Regulation 851, made under the Occupational Health and Safety Act, R.R. 1990, prohibits employees from exposing workers to an "equivalent sound exposure" level of 85dBA and that all three parties have recorded sound levels in excess of this level. The City of Toronto states that although the sound levels may not be constant, workers exposed to sounds above this level must wear hearing protection. It asserts that exposing residents to this level of noise for up to 17 months is clearly unreasonable.

In response, GO Transit indicates that although the project is long in duration, the project site is also very large and therefore the work is localized and the noise levels are not sustained at any one location as the pile-driving moves along the corridor.

Submissions on vibration measurements

For ease of reference, definitions of peak particle velocity (PPV) and Hertz are included in Appendix 1.

The WTDCG, the City of Toronto and GO Transit all made reference to the City of Toronto's Bylaw No. 414-2008 regarding vibration levels. This bylaw states that, "No person shall carry on a construction activity resulting in construction vibration that exceeds the levels set out in Table 1.0…"

Table 1.0 "Prohibited Construction Vibrations"
Frequency of Vibration
Vibration Peak Particle Velocity

Less than 4


4 to 10


More than 10


In December 2008, GO Transit established a base line pre-construction ground vibration environment around the site to be in the range of 0.2mm/sec to a max of 8.4mm/sec. The highest vibration levels were recorded near the NRT Building.

GO Transit submitted weekly reports on vibration levels taken from various locations around the project site. These weekly reports indicated that vibration levels were at their highest in February 2009, at a location between CN and CP track, above a storm sewer near Osler Road, when levels reached 39mm/sec. High levels of 31.1mm/sec at 24 hertz were also recorded by GO Transit in this same area on April 12, 2009. GO Transit also submitted isolated recordings higher than those permitted in Table 1.0 above, in May, June and July 2009 but explained these as being caused by the start up or shut down of the computer­-controlled vibratory hammer or when this hammer encountered an underground obstruction. All other vibration levels recorded in the weekly reports were below the maximum levels set out in Table 1.0. Furthermore, GO Transit's monitoring reports indicate that the vibration levels at a distance of 35m from the source were in the range of 1.7-14mm/sec at more than 10 hertz.

GO Transit maintains that the numerous claims of property damage caused by excessive vibration referred to by the WTDCG have not been reported to GO Transit. Only a small number of minor damage claims have been reported to GO Transit, and it is arranging for repairs even though it asserts that they are probably not related to the project.

Submissions on noise mitigative measures

Following collaborative meetings between the parties, GO Transit submits that it has attempted to implement some noise mitigative measures, including:

1. Vibratory Hammer

GO Transit states that there are methods of installing piles that use vibration rather than impact to install a pile. However, these methods have more difficulty overcoming dense soil conditions at depth. GO Transit also indicates that vibratory hammers have more difficulty achieving the accuracy of installation required for the interlocking piles used in this project. GO Transit also asserts that although vibratory hammers produce less noise than impact hammers, they do cause vibration, which can be unsettling for people. GO Transit notes that a smaller vibratory hammer has been in use since the beginning of construction for installing short temporary piles used to hold the pile-driving template in place, and for the removal of piles when necessary.

According to GO Transit, it employed a unique computer-controlled vibratory hammer from France which offered much greater control of vibration levels, allowing the operator to avoid levels that can be damaging. This hammer is one of only five in the world. Although the WTDCG asserts that the use of this technology made a noticeable difference, making the noise and vibration caused by the pile-driving more manageable, GO Transit asserts that it made for slower progress and, because of the variation in soil conditions, it has not been able to fully install some piles. These then have to be finished with an impact hammer. In August 2009, after 3 ½ months, GO Transit discontinued use of the computer-controlled vibratory hammer because it experienced an increasing number of breakdowns and required a complete overhaul.

The WTDCG submits that although none of the technologies can be described as pleasant, the computer-controlled vibratory hammer does not produce the extreme noise energy pulse and is much more tolerable as reported by some residents. The WTDCG also asserts that this hammer offers a far superior, less "impactful" approach, both with respect to noise and vibration.

2. Giken Hammer

GO Transit also submits that a silent pile-driving method has been developed by the Giken Corporation in Japan which hydraulically presses piles into the ground. A report produced by the Giken Company, and submitted by GO Transit, observed the loudest component of the Giken hammer, the power pack, produces a noise level of about 75dB from 1m away. The report indicates that this is within acceptable levels for noise in urban areas. Furthermore, the report states that ground vibration is reduced by 10-50 times compared to conventional impact hammer methods.

There are only two existing Giken hammers in the world with the capacity to install piles on this project and GO Transit advises that it will use one of these to install 250 piles which are in very close proximity to industrial buildings in poor condition, such as the NRT building. GO Transit states that the Giken technology will replace an impact hammer when it arrives.

GO Transit submits that the drawback of this machine is that it can install only two piles per day, as compared to 10 or 11 piles per day that can be installed with impact hammers. GO Transit predicts the 250 piles scheduled to be installed with the Giken method will take approximately six months to complete. However, GO Transit adds that it is not a certainty that the Giken hammer will be able to successfully install the required piles as it is untested for use on this project.

GO Transit also submits that to complete the remainder of the project using the Giken Hammer would take approximately two and a half years, thereby moving the project completion date back to 2014, and area residents may find the noise and dust for such a prolonged period of time to be more unpleasant that the current noise level.

The City of Toronto submits that a delay in the project completion date would be reasonable and appropriate if the expanded use of the Giken and the vibratory hammer technologies can reduce the impact of the level of noise on the local community. The WTDCG submits that constant exposure to 75dB noise from the Giken power pack is less immobilizing and cognitively distracting than the noise energy impulses of the impact hammer which can peak at 115dB. The WTDCG asserts that extending the project deadlines while using less invasive and destructive methods is the preferable option.

3. Measures to be used with the Impact Hammer

At the time of GO Transit's latest submission, it indicated that three impact hammers were in use. It is acknowledged by GO Transit that this technology has the more severe noise impact and GO Transit has implemented the following noise attenuation measures to reduce the impact of these machines:

  1. Chasers
    • For final pile-driving, GO Transit explains that a "chaser" is used between the pile-driving head and the pile itself. To mitigate the noise, GO Transit installed plates inside the chaser and filled the chaser with rubber.
  2. De-powering impact hammer
    • According to GO Transit, de-powering the impact hammer at the start of installation also helps mitigate noise. However, the trade-off is that more blows are required to fully install each pile.
  3. Shrouds
    • GO Transit evaluated the use of three-sided shrouds or enclosures around the impact hammers and found that these shrouds are effective, but only in three directions with the noise being amplified in the fourth direction, out of the open side. Consequently, GO Transit deemed shrouds to be ineffective for this situation.
    • GO Transit also designed and tested a four-sided shroud, but it states that it caused the machines to overheat such that it became necessary to open the shrouds, particularly on hot days.
  4. Skirts
    • GO Transit advises that sound absorbing skirts have been added to the templates, which are used to place the pile in the exact location of installation. GO Transit states that the skirts help control the noise at ground level which is where the loudest noise of installation occurs.
  5. Ground-level Sound Walls
    • GO Transit indicates that it uses ground-level sound walls which are positioned around the work, where space is available and no safety hazard is created. The WTDCG states that these sound barriers were only used for isolated roadside work located adjacent to Weston Road.

GO Transit states that, as shown in its noise measurements taken on June 12, 2009, the combined mitigative measures reduced the recorded noise levels by between 8dBA-14dBA.

The WTDCG states that all of the mitigation methods that were eventually used by GO Transit do not impressively address the basic failings of the impact hammer technology - noise and vibration. The WTDCG asserts that impact hammers are not by design remediable to the social context in which they are working, and notes that GO Transit expresses no concern whether the choice of impact hammer pile-driving is a reasonable use of technology given the context and duration of the construction.

4. Limited hours for pile-driving activities

In its July 22, 2009 answer to this complaint, GO Transit states that pile-driving activity on this project has been generally limited to about 40 hours per week, between approximately 8:00 a.m. and 4:00 p.m. weekdays, subject to certain exceptions for work required at night due to road closures or scheduled train blocks. GO Transit maintains that it is operating within the City of Toronto bylaws which do not set any limits on noise levels but instead regulate hours of work and require work to take place only between 7:00 a.m. and 7:00 p.m. on weekdays and between 9:00 a.m. and 7:00 p.m. on Saturdays.

The City of Toronto submits that, given the unusually disruptive nature of the project, the Agency should issue an order binding GO Transit to limit all pile-driving between 8:00 a.m. and 4:00 p.m. Monday to Friday and between 10:00 a.m. and 3:00 p.m. on Saturdays. However, in response, GO Transit contends that limiting the hours to between 8:00 a.m. and 4:00 p.m. Monday to Friday and 10:00 a.m. to 3:00 p.m. on Saturdays would frustrate the project, given that part of the work can only be carried out at night or on weekends when long train blocks are required. Furthermore, for certain work, GO Transit states that it requires road closures which the City of Toronto only allows at night or on weekends.

The WTDCG is adamantly opposed to pile-driving activities taking place on weekday evenings and Saturdays. Both the City of Toronto and the WTDCG argue that the constant noise at this level is clearly unreasonable, whatever its purpose. They are also concerned with the long-term effects on residents of being exposed to the current noise levels for even 40 hours a week for more than 17 months.

5. Communications

GO Transit points out that it has added a public relations liaison component to the project and has built a community outreach team which is available full-time on the site to respond to concerns of local residents and business owners and to provide ear plugs and free entertainment tickets to residents who complain about the noise.

The WTDCG maintains that it has been impossible to reach a GO Transit employee and that local citizens are not interested in ear protection and free entertainment tickets as a long-term solution to the noise issue. The WTDCG complains that there has not been adequate notice provided for variance in times that construction is to take place.

Concluding submissions

GO Transit states that while there is disruption associated with the project, there are also significant long term benefits to the community. In response, the WTDCG states that none of the long term benefits will be realized by the local community as the purpose of the project is to improve commuter services for persons who live beyond the West Toronto Junction.

The WTDCG states that, "The heart of its position is that it wants a semblance of predictability in the lives of the citizens of the community, and wants the most current and the quietest technology reasonably possible to be employed to the greatest extent possible."

GO Transit states that it understands and respects the community's concerns about construction noise, and it asserts that much was done to mitigate impacts both prior to construction of this phase of the project and since construction started in January 2009. GO Transit states that, unfortunately, construction is by nature disruptive, and impacts can be reduced but never completely eliminated.

Analysis and findings

The law

The most recent amendments to the CTA, introduced through Bill C-11 in 2007, included the addition of provisions in relation to noise and vibration caused by railway companies in the construction and operation of railways. Specifically, section 95.1 imposes an obligation on railway companies to only cause such noise as is reasonable in the circumstances, section 95.3 provides the Agency with a complaint adjudication function and section 95.4 clarifies that these provisions also apply to public passenger service providers, the definition of which includes urban transit authorities such as GO Transit.

It is clear from the legislative framework and the national transportation policy contained in section 5 of the CTA that, in exercising its mandate under section 95.3, the Agency must balance the interests of the parties. Railway companies and urban transit authorities, on the one hand, are involved in activities that necessarily cause noise and vibration, and these activities are also required to fulfill their various level of service obligations and operational requirements, and to maintain the "competitive, economic and efficient national transportation system...that serve[s] the needs of its users, advance[s] the well-being of Canadians and enable[s] competitiveness and economic growth in both urban and rural areas throughout Canada.". However, on the other hand, the interests of communities affected by this noise and vibration must be considered, first, by the railway companies and urban transit authorities in determining how best to perform the activities in order to meet their obligation under section 95.1, and, then, by the Agency in the determination of whether the noise and vibration being caused is reasonable in the circumstances.

This case

The Agency recognizes the need for this project to improve efficiency and expand commuter rail services in the Greater Toronto Area. It also recognizes that, due to the confined rail corridor's geographical location and soil conditions, the construction of retaining walls made of interlocking steel pipe piles is required to grade separate the West Toronto Diamond. However, the Agency must balance the need for this project and the necessary work as well as the construction methods used to carry out the work against the interests of the people in the local community who are being exposed to noise and vibration from the project.

The Agency notes that GO Transit has attempted to incorporate a number of techniques to reduce the noise and vibration produced by the pile-driving required for the project. However, the noise and vibration continue and, as the duration of the project has been extended until June 2010, they will continue for some time.

The Agency has reviewed the noise measurements taken by the parties and notes that different noise metrics were used by GO Transit (dBA/dbAi), the City of Toronto (dBA) and the WTDCG (dB/dBC).

The Agency notes that the long-term equivalent A-weighted sound level (Leq) and day and night average noise levels are generally found to be good descriptors for noise. However, exposure to pile-driving activities is typically measured as a C-weighted day-night level (on a C-weighted scale rather than on an A-weighted scale) or in dBAi.

The Agency is of the opinion that although the noise emitted from the impact of a pile-driving hammer is generally considered to be an impulse or transient noise, pile-driving activities as a whole are considered to be a continuous event. There is no doubt that the impact of the pile-driver being reproduced hundreds of times a day, will induce noise-related annoyance within the affected population. This type of noise should be assessed in terms of human annoyance impact.

In general, the noise level criterion for impact assessment should be carefully selected. The criterion should give an appreciation of the noise level as a function of the percentage of time that this given level is exceeded. The criterion should also allow for consideration of duration. The effect of a continuous event, repeated 100 times a day, such as the impact of a pile-driver, would not be the same as that of a punctual event occurring, for example, fewer than five times a day.

The U.S. Committee on Hearing, Bioacoustics and Biomechanics, Assembly of Behavioral and Sciences in 1981 developed a table that compares equivalent A-weighted and C-weighted noise levels in terms of their "percent highly annoyed" impact. In terms of annoyance effect of noise, as dBC and dBA levels increase, there is a corresponding increase of reported levels of annoyance such that levels 48 dBC and 50 dBA correspond to 2 percent of the population being highly annoyed whereas 69 dBC and 75 dBA correspond to 35 percent being highly annoyed.

Even without reference to the US Committee Table referred to above and despite the fact that the parties may not agree on the noise measurement methods or metrics used, whether they have been expressed in terms of dB, dBA, dBAi or dBC, the measurement results lead to the same conclusion. That is, all noise measurements indicate that the project is subjecting local residents to high and constant noise levels over an extended period of time. No one disputes this fact.

The Agency notes that the Ontario Health and Safety Regulations require the use of ear protection for sustained exposure to noise above 85dBA. From the submissions, it is apparent to the Agency that exposure to noise in the area of the project has been and will continue to be at or above these levels for many months to come.

The Agency agrees with the WTDCG that the quietest technology reasonably possible should be employed to the greatest extent possible. Given the submissions, the Agency is of the opinion that GO Transit is not fully implementing all reasonable measures possible to mitigate the noise given the nature of the noise and the fact that the local area is a high density mixed residential area.

In terms of vibration, pile-driving activities usually generate peak particle velocities of 1-3mm/s at 50m from the source depending on soil conditions and piling techniques used. In this case, the vibration data provided by GO Transit indicates that vibration is in the range of 3-5mm/s at 50m from the source and 1.7-14mm/s at 35m from the source which is higher than usual pile-driving activities but lower than the maximum outlined in the City of Toronto Bylaw.

Below are the results of the Agency's analysis of the evidence as well as its finding on the reasonableness of the noise and its preliminary findings on the mitigative measures used by GO Transit.

1. Vibratory hammer

Vibratory hammers are generally found to be most effective in cohesionless soils when used in conjunction with low displacement piles, such as steel pipe piles used in this project. Cohesionless soils such as sand and gravel are best suited soils for vibratory hammer driving. With mixed or cohesive soils vibratory hammers can also be used where there is a high water content. GO Transit has indicated that the soil at this location consists of sand and till with a high water table. It may vary from clays to mixtures of clay, sand, gravel and boulders. This soil can be categorized as a mix of mostly cohesionless soil and some cohesive soil, both with high water content.

Therefore, the Agency is of the opinion that the combination of steel pipe piles and the type of soil in the project area is suitable for vibratory hammer pile-driving activities.

Certain vibratory hammers can control their amplitude and frequency, thus controlling the amount of vibration produced, presenting a distinct advantage over other vibratory hammers which do not have this capability. In addition, the Agency notes GO Transit's submission that with the use of the computer-controlled vibratory hammer, vibration is lessened and noise measurements produced lower sound readings (78dBA to 91dBA).

Notwithstanding that GO Transit has not submitted information regarding the modifying of a vibratory hammer's frequency settings, GO Transit has indicated that a vibratory hammer can be used, in certain soil conditions, to drive some piles to the full depth. The Agency is therefore of the opinion that vibratory technology should be used to the maximum extent. Where this is not possible, the vibratory technology should be used to drive piles to the maximum possible depth and then an impact hammer used to complete the pile-driving activities. This would limit the number of strikes required by an impact hammer and likely minimize the wear and tear on a vibratory hammer.

The Agency finds that even though the use of a vibratory hammer in conjunction with an impact hammer would involve more time and more work to set up two hammers for each pile, this would be reasonable, when weighed against the high noise levels currently experienced in the densely populated surrounding area.

The Agency is also of the opinion, based on the above, that although GO Transit has removed the computer controlled vibratory hammer from the project due to mechanical problems, it is not reasonable to abandon the use of the vibratory technology simply because of maintenance requirements.

2. Giken hammer

GO Transit states that the Giken hammer is scheduled to be used to install 250 piles, which should take until February 2010. However, the Agency is of the opinion that the use of this hammer in conjunction with the other vibratory hammers discussed in this decision could be continued for the entire duration of the pile-driving activities.

The Agency finds that the use of the Giken hammer until the end of the pile-driving activities, now scheduled to June 2010, would allow for less noise and vibration disruption in the most sensitive areas as, by using GO Transit's projected schedule, at least another 150 piles could be installed in this manner.

Furthermore, the Agency acknowledges the City of Toronto and the WTDCG positions that a delay in the project completion date would be reasonable and appropriate if less invasive technologies were used to reduce the impact of the level of noise and vibration on the local community.

While GO Transit submitted that it would be unreasonable to extend the project by the time required to complete the pile-driving activities using only the Giken hammer, GO Transit has not provided reasons or evidence to substantiate why it would be unreasonable to extend the project by continued use of the Giken hammer.

The Agency is of the opinion that the speed with which the project can be completed should not be the determinative factor in the method of construction given the nature of the noise and vibration caused by this project and the impact on the community. The Agency also notes that GO Transit has failed to provide any commercial feasibility arguments or financial impact analysis to support its position that extending the completion date of the project would be unreasonable.

3. Measures to be used with the impact hammer

The Agency does note that the noise levels for the impact hammers have been reduced by 8-14 dBA with the combined use of various types of noise attenuation measures referred to previously. However, when the noise attenuation measures were employed, the noise levels generated from this hammer were still, as reported by GO Transit, between 96 and 107 dBA.

Therefore, the Agency is of the opinion that the impact hammer should only be used in this densely-populated urban area in conjunction with the vibratory hammer or in cases where GO Transit can clearly demonstrate that no other method is technically or commercially feasible.

The Agency notes GO Transit's statement that de-powering the impact hammer at the start of installation decreases the noise; however, GO Transit does not discuss the possibility of decreasing the hammer energy (such as using additional lighter blows per minute rather than fewer blows with heavier impact) for the entire pile installation process.

The Agency is of the opinion that when it is necessary to use the impact hammers, the hammers should be de-powered and energy be decreased to the furthest extent possible, and shrouds, skirts and rubberised chasers should be used. In addition, moveable noise barriers must be set up to deflect noise from the fourth, open side of the shroud, and any opening in the shroud should always be positioned down the tracks and not toward any residential area.

The Agency also notes that GO Transit has not submitted information regarding the use of an impact-vibration hammer which switches automatically from one mode to another depending on soil resistance. The Agency is of the opinion that this hammer should be considered as an alternative to using impact hammers alone.

With careful planning, it is possible to maintain a highly efficient work productivity with a reduced noise output. In order to do so, it is necessary to identify, in chronological order, the various tasks with their associated equipment. This information, along with accurate sound level measurements, would allow for a prediction of the noise that will emanate from the construction site and allow this level to be monitored. Communication of such sound level measurements and construction scheduling information, would also provide local residents with the predictability that they require to plan their activities and to minimize the impact of noise from the project on their lives.

4. Limited hours for pile-driving activities

The WTDCG is adamantly opposed to any work taking place outside of the hours of between 8:00 a.m. and 4:00 p.m. on weekdays. GO Transit has said that, in general, work is restricted to these hours; however, some work cannot take place within these time constraints given the City of Toronto's road closure bylaws and the long train blocks required by other railway companies operating in the area. The Agency is of the opinion that, in general, pile-driving activities should be restricted to weekday hours given their impact on the surrounding community.

The Agency is of the opinion that GO Transit must negotiate an agreement with the other railway companies to permit train blocks, which involve the temporary diversion of traffic and the closure and removal of tracks for set periods of time, during weekday hours to allow the pile-driving activities to take place at those times.

The City of Toronto is in favour of limiting the hours during which pile-driving activities are performed, but its own bylaw restricting road closures prevents all work requiring road closures from taking place during weekdays. The Agency is of the opinion that the nature of the noise and vibration and its impact on the community dictates restricted weekday times for pile-driving activities such that GO Transit must negotiate an agreement with the City of Toronto that provides for daytime road closures thus permitting the pile-driving activities to be carried out during weekday hours.


The Agency also notes that the WTDCG complaint concerned vibration as well as noise; however, the parties did not address vibration as comprehensively as they did noise. Evidence from persons in the community described the noise and vibration combined as being similar to the shelling in a war zone, and individuals complained of damage to items inside their houses (as, for example, items falling off of shelves because of the vibration) as well as damage to their houses in the nature of cracks in their foundations and walls.

GO Transit submitted isolated vibration level measurements which indicated that the vibration levels at the start of the pile-driving activities did exceed the City of Toronto Bylaw 414-2008, although when measured from a distance of 35m from the source, the levels were in the range of 1.7-14mm/s which is well below the maximum levels set out in the Bylaw. The Agency notes that between April and July 2009, while the computer-controlled vibratory hammer was in use, the levels recorded by GO Transit did not exceed the maximums set out in the Bylaw except at start up or shut down of that vibratory hammer. The Agency finds that the measures set out in the show cause below are required to achieve and maintain lower vibration levels as well as address the current noise levels. The Agency further notes, with approval, GO Transit's submission that it is dealing directly with all claims of property damage and, accordingly, local residents have direct recourse to making claims to GO Transit.

5. Communications

Although GO Transit has added a public relations person on site to provide information and give residents ear protection and entertainment passes when they complain, the WTDCG does not find this useful. In particular, the WTDCG complains about the lack of certainty around the timing of the pile-driving activities, both active and inactive periods. Given the effect of the noise and vibration from the project on the community, the Agency is of the opinion that more should be done by GO Transit to provide people in the community with the information that they need, regularly, and in advance, to determine the periods of greatest and least impact, and to understand the nature of the noise being caused by the project as well as its expected duration at their location. The Agency is of the opinion that GO Transit must develop a more comprehensive communications system that would include:

  1. a regularly updated Web site to provide the following information:
    1. a schedule of work, including detailed information about the current pile-driving activities and associated equipment on the site, projected activities and their location for the following two weeks, as well as any upcoming periods of inactivity;
    2. its schedule for long train blocks;
    3. at least 2 weeks' notice of any change to the project plans, including the schedule for pile-driving activities and any projected periods of inactivity;
    4. a weekly report on noise and vibration levels measured at various distances from the source at the project; and,
  2. an e-mail address and phone line, both to be answered by a person knowledgeable about the project and its schedule, for residents to communicate particular concerns about the current and projected pile-driving activities. GO Transit must follow up on all complaints received in this manner within 48 hours of their receipt.


Subject to a final determination by the Agency on mitigative measures under section 95.3 of the CTA, the Agency finds that, although GO Transit may have operational requirements which necessitate this construction project, the prolonged exposure of the local citizens to the noise and vibration generated from the pile-driving activities is unreasonable given the nature of the area in which the construction is taking place and the failure by GO Transit to implement sufficient mitigative measures. Accordingly, the Agency finds that GO Transit is in breach of its obligation under section 95.1 of the CTA to cause only such noise and vibration as is reasonable.

Direction to show cause

Before making a final determination as to any mitigative measures required to be implemented, and before the Agency orders GO Transit to undertake any changes to its project, the Agency will provide GO Transit with the opportunity to comment on the proposed mitigative measures.

Based on the above, GO Transit is directed to show cause why it should not be required to implement the following measures with respect to the noise and vibration caused by pile-driving activities at the project:

  1. Vibratory hammer
    1. Use a vibratory hammer to completely install the piles by modifying the hammer's frequency settings and, where this is not possible, drive the piles to the maximum depth possible considering soil conditions and then finish the pile-driving activities with an impact hammer.
  2. Giken hammer
    1. Extend the use of the Giken hammer in conjunction with vibratory hammer use, as discussed in this Decision, for the entire length of pile-driving activities and not just until the scheduled 250 piles are installed, especially in the more sensitive areas;
  3. Impact hammer and related mitigative measures:
    1. Use an impact-vibration hammer which switches automatically from one mode to another depending on soil resistance. Alternatively, use the impact hammer on the project only in conjunction with a vibratory or Giken hammer and only where it has been demonstrated that no other method is technically or commercially feasible.
    2. De-power the impact hammer and decrease the hammer energy wherever possible and use shrouds, skirts and rubberized chasers. Any opening in the shroud should always be positioned down the tracks and not toward any residential area;
    3. Employ moveable noise barriers to deflect noise away from nearby residential areas by moving them to current pile-driving locations and by setting them up around the shrouds to deflect noise from the fourth, open side of the shroud;
  4. Limited hours for pile-driving activities
    1. Restrict the hours of work for installing piles to 40 hours per week from between 8:00 a.m. and 4:00 p.m. on weekdays;
    2. Negotiate an agreement with the City of Toronto to allow for road closures during the weekday hours to complete the required work at that location between 8:00 a.m. and 4:00 p.m. on weekdays;
    3. Negotiate agreements with other railway companies to allow for train blocks during the weekday hours to complete the required work at that location between 8:00 a.m. and 4:00 p.m. on weekdays;
  5. Noise and Vibration Monitoring
    1. Prepare a proposed method to provide weekly noise and vibration level measurements, including equipment to be employed, method of measurement and associated metrics, and the criteria for selecting the location of noise measurements
  6. Communications
    1. Develop a more comprehensive communication system including a Web site which is updated daily, to communicate information to local residents including detailed information about the current pile-driving activities and associated equipment on the site, projected activities and their location for the following two weeks, as well as any projected periods of inactivity;
    2. Provide at least 2 weeks' notice of any change to the project plans, including the schedule for pile-driving activities and any projected periods of inactivity;
    3. Have an e-mail address and phone line, both to be answered by a person knowledgeable about the project and its schedule, for residents to communicate particular concerns about the current and projected pile-driving activities. GO Transit is to investigate and respond within 48 hours;
    4. Post on the Web site a weekly report containing the results of noise and vibration measurements as well as an assessment of the effectiveness of mitigative measures implemented; any complaints received, and how they were addressed and resolved; and, any changes to the project schedule.

If there are technical and commercial reasons why GO Transit cannot implement any of the measures set out in this show cause, GO Transit must provide detailed evidence for consideration by the Agency. The Agency will also consider submissions by GO Transit as to reasonable additional or alternative measures.

GO Transit is required to respond to the above-noted direction within 14 days from the date of this Decision. The Agency will allow the City of Toronto and the WTDCG an additional five days to submit any final comments on GO Transit's submission. The Agency will then assess the information and make its final decision in this matter pursuant to section 95.3 of the CTA.

Should you have any questions relating to this case, you may contact Katie Fillmore, by telephone at 819-953-8522, by facsimile at 819-953-8353, or by e-mail at Katie.Fillmore@cta-otc.gc.ca and Patricia Lavigne, by telephone at 819-953-0318, by facsimile at 819-953-8353, or by e-mail at Patricia.Lavigne@cta-otc.gc.ca.

Appendix 1 - Glossary of terms and abbreviations

dB: decibel, aA logarithmic unit that accounts for the large variations in amplitude and, is the accepted standard unit for the measurement of sound.

dBA: A-weighted decibel scale, commonly used to describe the sound level heard by the human ear.

dBAi: A-weighted decibel sound pressure level of an impulsive sound measured with a sound level meter set to "impulse" response.

dBC: C-weighted decibel scale used as a descriptor of low-frequency impulse noise sources such as lightning, blast noise and sonic booms.

dBA Leq: the long-term equivalent A-weighted sound level

Equivalent sound exposure level: also called Noise exposure level, Lex,8 - The normalized noise exposure over an 8-hour period.

Hertz: a unit of frequency equal to one cycle per second

Peak Particle Velocity (PPV): a measure of vibration intensity.

Diesel Impact Hammer: basically raises and drops its weight or ram by exploding diesel fuel and air compressed by the falling ram. When the fuel explodes, the ram rises for the next stroke and repeats itself until the fuel is shut off. It is a one cylinder two-stroke engine that uses the falling piston as the ram to drive the piles. The diesel hammer is characterized by light weight and relatively inexpensive operation costs.

Vibratory Hammer: operates on the basis of vibration from the machine causing temporary disturbance of the soil around the pile, causing minor liquefaction, which results in a noticeable decrease in resistance between soil and pile. This enables the pile to be driven into the ground with very little added load, i.e., its own weight plus the weight of the hammer.

The vibratory hammer is made up of three components, the top (suppressor), the middle (eccentric gearbox or eccentric weights) and the bottom (clamping device). The device is first clamped to the pile then the eccentric weights are turned. As the eccentric weights begin to spin the device, the pile it is attached to begins to vibrate up and down in the soil. The soil becomes liquid or suspended, moving up and down rapidly with the pile.

Vibratory hammers apply an alternating and rapidly repetitive force to drive piles while impact hammers generate high forces to move the pile blow by blow. Vibratory hammers impart energy to the pile-soil system continuously rather than incrementally and impart a bidirectional force while impact hammers impart their motive force in a downward direction. Through soil response to vibration, vibratory hammers manage to get the pile down while applying bidirectional forces.

Impact-Vibration Hammer: imparts both vibration and impacts to the pile during operation. Impact-vibration hammers are different from purely vibratory ones because they can tune themselves to the conditions of the driving system. They can vary their striking energy with the increase in driving resistance. (They switch from one mode to the other depending on soil resistance.)

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