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The
Seattle Monorail project includes a complete noise
analysis as part of an environmental impact statement
to identify and evaluate potentially significant
impacts. The EIS was part of a phased SEPA review
process
Scope of
Work
We are conducting measurements of
the existing acoustical environment in and near
the project corridor with a series of sound level
meters at locations representing sensitive receivers.
These 24-hour measurements were used to document
the range of sound levels to help provide an indication
of typical levels that could be affected by monorail
noise.
The “Green Line” segment will cover
a 14-mile corridor serving communities from Ballard,
Fremont, Queen Anne, First Hill, Downtown Seattle,
International District, SODO, and West Seattle.
Expected noise levels from the Green Line monorail
were assessed using the Federal Highway Administration
(FHWA) Traffic Noise Model (TNM v. 2.1 – USDOT 2003).
With this tool, noise from the Green Line was estimated
based on monorail trains running on elevated guideways
along alternative alignments. Estimated noise levels
were compared with the noise impact criteria developed
by the Federal Transit Administration (FTA).
City
Noise Ordinance
Noise from construction
of the Green Line will be governed by the timing
restrictions and the noise limits included in the
City of Seattle noise ordinance. This ordinance
includes maximum permissible sound levels based
on the zoning of the source and receiving properties.
The ordinance also sets maximum levels and duration
of allowable daytime construction noise.
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