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HomeMy WebLinkAboutItem 3a: Discussion about Gold Line Sound Wall MaterialDATE: August 17, 2010 TO: Mayor and City Council STAFF REPORT Development Services Department FROM: Jason Kruckeberg, Development Services DirectorD Philip A. Wray, Deputy Director of Development Servces /City Engineer By: Linda Hui, Transportation Services Manager SUBJECT: REPORT, DISCUSSION AND DIRECTION REGARDING GOLD LINE SOUNDWALL MATERIAL Recommendation: Provide Direction SUMMARY The Development Services Department has been working closely with the Gold Line Foothill Extension Construction Authority (Authority) in developing project specifications for inclusion in the construction bid package for the Gold Line. Recently, the City has been given the opportunity to select a preferred soundwall material from two possible options which include 1) Fractured -fin Soundwall and 2) Metal Acoustic Soundwall. After both literature and field reviews on soundwall technology, it is recommended that the Council approve the Metal Acoustic Soundwall as a preferred technology for the soundwalls to be placed along the Gold Line alignment in designated areas within the City. BACKGROUND As part of the scope of the Main Alignment of the Gold Line Foothill Extension, areas abutting residential uses will be equipped with soundwalls. These areas in Arcadia include portions of the Garden neighborhood, Downtown Hotels and the Arcadia School District school site and the residential neighborhood east of Bonita Park. Based on the final Environmental Impact Report and the current preliminary engineering plan, the soundwalls are required only on the residential side of the track. DISCUSSION Traditionally, roadway /railway induced noise has been attenuated with sound barriers made of masonry (concrete) material. A concrete soundwall can sufficiently reduce noise if at a minimum the wall is tall enough to block the line -of -sight between the noise Staff Report Gold Line Soundwall Material August 17, 2010 Page 2 source and the receiver. But concrete surfaces tend to reflect noise at a higher decibel level than the original direct noise source. Noise reflection could be an unintended issue when there is a soundwall only on one side of the noise source. To address the noise reflection issue, sound absorptive technologies such as a metal acoustic soundwall have become a viable option. Metal acoustic soundwalls are coated steel modular panels filled with fiberglass, non - corrosive, weather -proof acoustic material for sound absorption. The panel coating comes in multiple colors and is graffiti resistant. The panels are easily replaceable. Installation of a metal acoustic soundwall along the Gold Line in South Pasadena has been successful and has served as a basis for viable soundwall alternative for the Gold Line extension. Thus, the Authority has given the City an opportunity to choose from two viable soundwalls options — fractured -fin and metal acoustic soundwalls. (See Attachments for photographs). Based on information received and field inspections, the metal soundwalls are a preferable alternative both in terms of appearance and performance. FISCAL IMPACT No fiscal impact is anticipated. RECOMMENDATION Staff recommends that the Council approve the Metal Acoustic Soundwall as a preferred technology for the soundwalls to be placed along the Gold Line alignment in designated areas within the City. Approved: P JK:PAW:LH:pa Donald Penman, City Manager Attachments: Photographs of Metal Acoustic Soundwalls and Fractured Fin Concrete Soundwalls Attachment Soundwall Examples Fractured -fin Soundwall Metal Acoustic Soundwall • Attachment Metro Gold Line — South Pasadena BNSF — Anaheim