Californian break-through for efficient noise and vibration monitoring

The joint venture SSH (Skanska-Shimmick-Herzog) was awarded the prestigious design-build contract for the BART extension to Berryessa, including line, track, systems and stations. The project-wide noise and vibration monitoring was won through a competitive bid process by the company ASC (Analysis & Solutions Consultants) headed by Dr Dots Oyenuga.

BART (Bay Area Rapid Transit) provides the commuter train connection between the three cities San Francisco, Oakland and Freemont. Now construction work has started for the missing extension to San Jose, the “capital” of Silicon Valley. The first 10-mile phase Freemont – Berryessa is projected to carry 23.000 weekday riders when in operation by 2017, thus relieving regional freeways from notorious congestion.

A cost-reducing monitoring system

The success of ASC is in large part due to the cost reducing and efficiency-enhancing INFRA measurement system and the distinctive features of its reporting facility INFRA Net. Thus even a small consultant company can handle the 10-mile alignment, the high number of monitoring stations and the public outreach required.

– We have used the INFRA system before on a couple of projects in the area, for example  The Sunnydale Tunnel Extension in San Francisco, says Dr Oyenuga. – INFRA offers the unique ability of using the same bus cable and data logger for measuring both noise and vibration. This provides savings when noise and vibration monitoring are coincident. Moreover the digital instrumentation provides more accurate data and more stable instruments than analogue alternatives and thus requires less maintenance.

– INFRA automates all monitoring data which means that reports are:
– easily generated
– easily archivable
– easily retrievable

A means to improve contractor efficiency

The INFRA system also offers several advantages to our customers, including real-time noise monitoring. This enables the contractor to provide abatement measures on-the-fly during construction, thus minimizing disturbance to neighbouring residents and businesses, Dr Oyenuga continues.

– Currently, we set up thresholds/trigger levels at each monitoring station. The thresholds are based on the results of a baseline study of ambient noise levels that we conducted prior to the start of construction.  If the thresholds are breached during construction, notification protocols are automatically triggered, and the relevant text messages are sent to a pre-defined list of stakeholders, informing them of the specifics of the breach.

– Our INFRA is performing as expected and we are receiving excellent support from the Swedish system producer Sigicom. With some scheduled software developments the system will provide facilities that sharpen its competitive edge still more, Dr Oyenuga concludes.