Appendix L.2 - Off-site Noise MemoAppendix L.2
Off -Site Noise Memo
Urban Crossroads, 2022
Travertine SPA
Draft EIR
SCH# 201811023
Technical Appendices
October 2023
��► URBAN
CROSSROADS
CROSSROADS urbanxroads.com
December 14, 2022
Mr. Mike Cho
TRG Land
898 Production Place
Newport Beach, CA 92663
SUBJECT: TRAVERTINE SPECIFIC PLAN OFF-SITE TRAFFIC NOISE MITIGATION MEASURES
Dear Mr. Mike Cho:
Urban Crossroads, Inc. is pleased to submit this Off -Site Traffic Noise Mitigation for the Travertine
Specific Plan ("Project"). This Off -Site Traffic Noise Mitigation has been prepared to supplement the
October 26, 2022, Travertine Specific Plan Noise Impact Analysis ("NIA") prepared by Urban Crossroads,
Inc. Based on the significance criteria in Section 4 of the NIA, the Project -related noise level increases
are considered potentially significant under Phase (2031) with Project conditions on the following
roadway segments:
• Avenue 58 west of Madison Street (Segment #1)
• Avenue 62 west of Monroe Street (Segment #6)
• Monroe Street south of Avenue 60 (Segment #8)
The three roadway segments estimated to experience potentially significant noise level impacts due to
Project -related traffic are located near the Project Site.
OFF-SITE TRAFFIC NOISE MITIGATION
To reduce the potentially significant Project traffic noise level increases on the study area roadway
segment, potential noise mitigation measures are considered in this analysis. Potential mitigation
measures discussed below include rubberized asphalt hot mix pavement and off-site noise barriers for
the existing residential uses adjacent to impacted roadway segments.
RUBBERIZED ASPHALT
Due to the potential noise attenuation benefits, rubberized asphalt is considered as a mitigation measure
for the Project -related roadway improvements associated with Project construction. To reduce traffic
noise levels at the noise source, Caltrans research has shown that rubberized asphalt can provide noise
attenuation of approximately 4 dBA for automobile traffic noise levels. (25) Changing the pavement type
of a roadway has been shown to reduce the amount of tire/pavement noise produced at the source
under both near-term and long-term conditions. Traffic noise is generated primarily by the interaction
of the tires and pavement, the engine, and exhaust systems. For automobiles noise, as much as 75 to
90 -percent of traffic noise is generated by the interaction of the tires and pavement, especially when
traveling at higher and constant speeds. (5) According to research conducted by Caltrans (25) and the
Canadian Ministry of Transportation and Highways (26) a 4 dBA reduction in tire/pavement noise is
attainable using rubberized asphalt under typical operating conditions.
Mr. Mike Cho
TRG Land
December 14, 2022
Page 2 of 2
While rubberized asphalt will provide some noise reduction, this noise study recognizes that this is only
effective for tire -on -pavement noise at higher speeds. Therefore, rubberized asphalt is not proposed as
mitigation for the Project and the off-site Project -related traffic noise level increases at adjacent land
uses would remain significant.
OFF-SITE NOISE BARRIERS
Since existing and future noise -sensitive receiving land uses are located adjacent to the impacted
roadway segments in the Project study area, off-site noise barriers were considered in this analysis as a
potential traffic noise mitigation measure to reduce the impacts. Off-site noise barriers are estimated
to provide a readily perceptible 5 dBA reduction which, according to the FHWA, is simple to attain when
blocking the line -of -sight from the noise source to the receiver. In addition, according to FHWA
guidance, outdoor living areas are generally limited to outdoor living areas of frequent human use (e.g.,
backyards of single-family homes). Therefore, front and side yards of residential homes adjacent to off-
site roadway segments do not represent noise sensitive areas of frequent human use that require
exterior noise mitigation.
However, the impact off-site roadway segments already benefit from existing off-site noise
barriers. Consistent with the County of Riverside Noise Element, these barriers were constructed to
mitigate the future long-range General Plan Roadway network and will provide the noise attenuation
needed to satisfy the 65 dBA CNEL exterior noise requirements. Increasing the existing off-site traffic
noise barriers is not anticipated to provide the FHWA attainable reduction of 5 dBA required to reduce
the off-site traffic noise level increases. As such, off-site noise barriers would not be feasible and would
not lower the off-site traffic noise levels below a level of significance, and therefore, noise barriers are
not proposed as mitigation for the Project. If you have any questions, please contact me directly at (949)
584-3148.
Respectfully submitted,
URBAN CROSSROADS, INC.
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Bill Lawson, P.E., INCE
Principal
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No. TR 2537
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12189-12 Offsite Noise Memo