04 Jun Transit Centre Acoustics
Where do buses start and finish each day? At a transit centre. These facilities are the hubs of public transportation systems in cities across the world. With buses, minibuses, and other vehicles coming and going all day—being parked, serviced, fueled, and washed—it’s no surprise that transit facilities can be noisy places. However, through good planning and thoughtful acoustical design, you can address transit centre noise, and benefit workers at the facility and people living nearby.
Over the years, we have consulted on many transit centre projects. In our experience we’ve found four prominent acoustical issues with transit centres that can be addressed during planning and design:
- Potential noise emissions to adjacent noise-sensitive areas
- Exterior noise ingress to operations and maintenance buildings
- Office acoustics
- Maintenance bay noise levels
Potential noise emissions to adjacent noise-sensitive areas
Inevitably, the regular and routine operations of transit centres generate noise that propagates beyond the facility boundaries. This noise can potentially disturb people in homes, schools, hospitals, offices, parks, or other noise-sensitive properties.
Noisy equipment associated with transit centres can include
- bus traffic;
- bus idling;
- backup alarms;
- maintenance activities;
- building mechanical equipment;
- and emergency generators.
On one project, we discovered that exhaust purging from diesel buses was a significant noise source.
To identify the possible effects of transit centre noise on nearby homes, conduct a noise impact assessment that evaluates the location of noise sources, amount of noise generated, activity schedule, proximity to noise-sensitive receivers, and baseline noise environment.
If the assessment predicts significant impacts at nearby noise-sensitive receivers, noise mitigation measures may need to be implemented. These measures can include the following:
- administrative measures (e.g., schedule or route adjustments);
- selecting quieter equipment;
- installing enclosures or silencers for noisy equipment;
- moving noise sources further away from noise-sensitive receivers; and
- installing noise barriers or earth berms to shield receivers from the generated noise.
Exterior noise ingress to operations and maintenance buildings
Similar to adjacent noise-sensitive properties, users of the transit centres, particularly those working in offices, could potentially be disturbed by the ongoing activity. Since these spaces are often much closer to the noise sources, the noise mitigation measures previously mentioned may not be practical or adequate. For new transit centre projects, there is an opportunity to review and select appropriate exterior wall constructions, windows, and doors to adequately reduce exterior noise ingress. Building facade upgrades can be combined with other noise mitigation measures to achieve satisfactory indoor noise levels.
In general, transit centres have few noise-sensitive spaces aside from private offices and meeting rooms. Nevertheless, noise-sensitive spaces should be identified and reviewed for appropriate acoustics. Interior partitions and doors should be analyzed to ensure they adequately reduce noise transmitted from adjacent spaces in the building. This is particularly important if these spaces are located beside noisy spaces such as workshops or maintenance bays. HVAC noise sources such as air handling units, fans, fan coils, and variable-air-volume (VAV) units should be reviewed to ensure background noise levels generated are acceptable and, if needed, plan for noise reduction measures.
Maintenance bay noise levels
While maintenance bays are not noise-sensitive, noise from maintenance activities is often made worse by the reverberant conditions inside. Typically, the walls, floor, and ceiling of repair bays are hard surfaces. This makes the space more reverberant. By making the space less reverberant, you can reduce noise exposure for workers in the bays, and limit noise breaking out of the bays to other spaces.
To reduce reverberation in a room, add acoustically absorptive surfaces. It’s important to select the right absorptive material, though, especially in busy, industrial environments like repair bays. While acoustically absorptive materials can have special maintenance requirements, there are some that are both absorptive and durable. Others are even washable. A qualified acoustician can help you select the right material, as well as the best location to install it—to optimize its effectiveness and limit possible maintenance concerns.
Plan Early and Avoid Issues with Transit Centre Noise
Acoustics may not seem to be a big deal for transit centres, but if we take a closer look at all the noisy activity happening on a day-to-day basis, there are quite a few noise issues that could become problematic if not dealt with early on.
These factors we discussed here are only the more prominent issues; there are more details that could be reviewed depending on the specific needs of your project. If you want to learn more about the acoustical design or noise impacts of transit centres or similar facilities, contact an acoustician at BKL, or have a look at some of our past projects, like the Hamilton Transit Centre.