2021 Rail Transit Session
Effects of a Conformal Frog Retrofit on Wayside Noise and Vibration on the Ottawa Trillium Line
City of Ottawa
The City of Ottawa follows the Environmental Noise Control Guideline (ENCG) for acceptable outdoor and indoor noise and vibration levels for residences located adjacent to rail corridors (during daytime and nighttime running). Following the construction of a siding, and to mitigate resultant impact noise from the No. 15 turnout frog, the City of Ottawa further implemented a slow-order speed restriction (50kph) to alleviate complaints where indoor noise conditions were still above the acceptable nighttime limits in the ENCG.
As a result from pressure on train operations and longer headways, the City of Ottawa investigated various N&V improvement solutions for the crossover with the intent to reduce noise in residences to be below ENCG limits while still maintaining the original non slow-order speed:
- Combination of Under Tie Pads & Under Ballast Mats;
- Isolation Trench;
- Installation of a new No. 15 Conformal frog; and
- Retrofit the existing frog with a conformal top process called Crossflo (product of Bombardier Transportation).
Implementing the lower cost field retrofit solution (Option D), the No. 15 turnout frog surface was modified with a TOR profile that matched the LRV wheel cross-section. While operating at 80kph in both travel directions, a 4 dBA reduction in the indoor Average Equivalent Sound Pressure Level (Leq, 1 hour) was achieved and approximately 30% reduction in the Average Maximum Measured 1/3 Octave Velocity Level (within 12m of the frog).
This will be a two-part presentation:
- City portion (by Rashid Dorj) would present the pre-mitigation conditions, the various considered solutions and the final noise / vibration results in post-mitigation: Bombardier portion (by Harry Skoblenick) would discuss the Crossflo process and how the technology was implemented: