Why Hiring a Specialist Can Help Avoid Unnecessary Features for Your Transit Project
The growth of cities is increasing the demands on transit systems. Whether it is above ground or below, municipalities everywhere are facing increased pressure to enhance transit services and expedite their transit projects to alleviate the traffic on existing systems and busy roads.
Transit Project Concerns Around Noise and Vibration
Neighbours and stakeholders are always concerned about transit systems being built too close to their properties. Case in point: When Minnesota Public Radio (MPR) discovered the new Central Corridor Light Rail Transit (CCLRT) project in Minneapolis-Saint Paul would be running within 14 feet of their existing recording and broadcast studios, they were worried the noise and vibration from the track design would be disruptive to their daily operations. So they took the matter to court.
Our team at Aercoustics was brought in as an expert witness to provide an unbiased, third-party peer review. We were able to predict the future noise and vibration levels of the transit project that generated the CCLRT operation and provided our expert opinion on whether the current system design would affect MPR’s operation. Our work confirmed the overall design strategy of the track system was sufficient in mitigating any potential noise and vibration issues and the lawsuit was ultimately dismissed.
These types of worries are not uncommon but with proper design and testing throughout the process, these concerns can be appeased.
Best Practices to Keep Transit Projects on Budget
For designers and contractors, there is tremendous pressure to meet the contractual requirements around the impacts of noise and vibration in a cost-effective and practical manner. All public private partnerships (P3) outline these requirements. It’s quite easy to make a quiet transit system if you overdesign and pay a lot of money. But in a fixed price bid, exceeding the budget isn’t an option.
How can the costs be controlled? How can complaints or worse be avoided in the first place? Having worked on transit projects across North America, we have gathered some insight into best practices when undertaking a major transit project.
1) Find a niche firm to help with the design:
If you had a very specific health issue, you would see a specialist. The same concept should be applied to highly technical engineering projects. There are noise and vibration experts who specialize in rail and transit systems. Testing requires specific equipment to measure impact below ground and requires a deeper understanding of the potential noise and vibration that emits by a railway or transit system. It is critical that you have experts that can deliver tailored, practical solutions to avoid designing a noisy system or incurring significant costs in over prescribed designs.
Ideally, you find a partner with a track record of working on municipal transit systems so they can apply their practical knowledge and an intimate working knowledge of regulatory requirements, operations, processes and track systems to your transit project. The right partner will guide your team in selecting the appropriate track measures to control noise and vibration while balancing cost and risk for P3 projects. They should be able to provide guidance for requirements and budget for construction noise and vibration monitoring for stations, tunneling, shaft locations and utility works.
A niche firm will also have an understanding of the various regulatory requirements. Depending on the transit project and the project’s location in Canada, there are municipal and provincial regulations to be considered.
Before hiring the consultant, conduct a thorough interview process to ensure they have the appropriate expertise for your transit project. Some questions to ask include:
- What was the last transit project you worked on and was it successful?
- Have you performed measurements of transit systems before?
- Can you share something to demonstrate your capabilities in this area?
This expert guidance will give your team the required confidence in managing the financial and technical risk.
2) Determine all noise and vibration needs during the bid stage:
A good partner will work with you at the bid stage to determine key areas and identify where potential floating slab systems may be needed to control noise and vibration. These include areas near sensitive spaces such as theatres, hospitals or even residential units if they are located in close proximity to the proposed alignment. There are many factors that a good partner can detect, such as whether the alignment is in bedrock or soil. Ensure the firm you are working with can provide sample designs with enough detail to appropriately cost and/or carry an allowance where the risk may be higher such as in theatres or performance spaces. Identifying the noise and vibration needs at the outset of the transit project will help control costs.
3) Budget for testing throughout the project:
Any assumptions made in the bid stage will need to be verified in later stages of the design. From design to operations and maintenance, testing will ensure your transit project is operating in compliance with the various levels of noise and vibration regulations. It is almost impossible to analyze how the ground moves. Whether it is stiff clay or cohesion clay, it all affects noise and vibration. Firms need to budget for ground propagation testing in the initial plan to determine the appropriate amount of noise mitigation measures that will be required. Whether at ground level or sub-grade, this testing service shakes the ground and measures how vibration waves move in the earth. This field data is then used to determine and optimize the track system to achieve contractual limits while leaving enough headroom for normal wear-and-tear on a 30-year operating contract. During construction, noise and vibration studies are required to monitor noise levels. As many of these transit projects are located in densely populated residential areas, they require regular noise monitoring to ensure agreed-upon noise limits are not exceeded. In the final stages of construction, testing can determine whether vibration control measures have the predicted effect. Periodic testing throughout will ensure that the transit system is maintaining noise and vibration levels so be sure to budget for it at every step of the process.
Whether it is through advanced modelling techniques or custom in-house developed software, the data gathered in testing can help assist the architect in selecting the type, placement and amount of acoustic treatment that lines up with the aesthetic vision of the transit project.
Measure Twice, Cut Once
Rail noise and vibration issues are not easy to fix after construction, so it is critical to do it right the first time. Fixing it later may require stopping service for a few years to correct the issues. Whether it’s external or coming from within a building, vibration forces can pose significant architectural and structural concerns, not to mention impact people working and living nearby.
It is critical to hire someone with the right expertise to assess the noise and vibration impact of transit on buildings and design those buildings to mitigate the effects. Accurately predicting noise and vibration from the outset will provide a more accurate budget for the transit project and is key in ensuring the maximum enjoyment of any space.