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1、Portland, OregonNOISE-CON 20112011 July 25-27Automatic wireless sound monitoring system and its application at Caldecott TunnelMei Wua) Email: meiwumei- Mei Wu Acoustics3 Twin Dolphin Drive, Suite 190Redwood City, CA 94065Stewart Heb) Email: stewart.hepsw-PSW Technology2063 Seabrook CourtRedwood Cit
2、y, CA 94065This article presents an automatic wireless sound monitoring system. The system posts sound levels on a website at a pre-set time interval and therefore eliminates the need for regular site visits to confirm the operating status of the monitors and to download data. In addition to regular
3、 data posting, the system sends out instant text messages to computers and cell phones when the pre-set sound criteria are exceeded. This allows the system to be used for construction noise monitoring. To help the construction team to identify the noise sources of an exceedance event, it also posts
4、the audio recording of the events. The system has been monitoring construction noise at Caldecott Tunnel Fourth Bore in California since May 2010. 1INTRODUCTIONA fourth bore is being added to Caldecott Tunnel on Highway 24 in California to provide two additional lanes to relieve the daily traffic bo
5、ttleneck. When completed in 2013, the new 3,389-foot-long tunnel will have two 12-foot lanes, shoulders and emergency walkways. In response to the noise concerns of the residents around the construction site, Caltrans (California Department of Transportation) has agreed to monitor evening and nightt
6、ime noise in residential neighborhoods near the tunnels west portal. Figure 1 shows the six community sound monitoring stations and the vicinity map of the construction site.The project has distinctive requirements for sound monitoring such as continuous sound monitoring, instant alarm of any exceed
7、ance, and audio recording of all exceedance events. The construction team is required to stop construction within 20 minutes of any noise exceedance unless it is verified that the exceedance is not caused by construction activities. To fulfill these distinctive requirements, we developed a new wirel
8、ess sound monitoring system with Scantek. Figure 2 shows photos of two monitoring stations. 2 PERFORMANCE REQUIREMENTSThe following are some of the performance requirements for the wireless sound monitoring system.Sound Level Meter The project specifies Type II sound level meters that meet ANSI S1.4
9、:83 (A1:85) and ANSI S1.43:97 standards.Sound Monitoring The project requires continuous sound monitoring at 6 community stations plus 4 construction stations. It requires public posting of hourly Leq and Lmax, in dBA from 7 pm to 7 am for the community monitoring stations. Noise Criteria The projec
10、t requires a two-week continuous noise monitoring at each community monitoring station before the start of any construction work. Based on the monitoring results, the Leq and Lmax criteria are established for each station at each hour between 7 pm and 7 am for weekdays and weekend days. Instant Alar
11、m The project requires the construction team to stop working and apply noise control measures within 20 minutes when the sound levels exceed the criteria at any monitoring station. To meet this requirement, the construction team needs to be notified as soon as an exceedance event occurs.Noise Source
12、 Identification Since the community monitoring stations are located in populated areas, the exceedance events can be caused by community activities such as dogs barking or cars driving next to the monitoring station. The construction team needs the ability to identify the noise source within 20 minu
13、tes of an exceedance event.Internet Connection Some monitoring stations are located in areas where cell phone signal is so weak that we had trouble making cell phone calls. The wireless monitoring system has to function in these areas. Weather Factor The system has to withstand Californias strong su
14、mmer sun, frequent winter rains, and high wind at the hilltop stations. Public Website A public website is required to serve daily data for public viewing.Engineering Website The construction team should have a password-protected private website with engineering details. Record Keeping All records a
15、re to be archived for future examinations. 3SYSTEM DESIGN CONSIDERATIONS AND BASIC COMPONENET PERFORMANCEThe basic components of the system include a sound level meter at each monitoring station and a PSW wireless package. The sound level meter measures sound levels. The PSW wireless package compare
16、s the levels with the criteria and posts them on the websites. When an exceedance event happens, the wireless package sends out alarms and posts the event audio recoding. The system operates automatically. Sound Level Meter the system is designed to work with CESVA SC-160, a Type II sound level meter meeting the ANSI standards. For proj
