The paper examines the methodologies and evaluation criteria advocated by the U.S. Federal Transit Administration (FTA) and Federal Rail Administration (FRA) used to determine whether or not a proposed alignment for a transportation project adversely impacts affected land uses, such as research & development and high-technology manufacturing. The criteria in question are applied as limits on vibration and noise at sensitive receiver locations. Both short-term construction and long-term transportation operations are typically considered, with the latter being the focus of this paper. A case study is presented of a proposed transit system that passes through four different soil zones, the operational characteristics that are required to generate a vibration level equal to the FTA/FRA advocated level of 65 VdB re: 1 micro-inch/sec, and the range of variability of the acceptability of the vibration conditions when considered in terms of third-octave bands compared to vibration criterion (VC) curves that are used as the design performance targets of vibration-sensitive facilities.
The paper presents a review of generic vibration criteria used for vibration-sensitive technical facilities. The paper reviews the logic behind and evolution of the Vibration Criterion (VC) curves, originally known as the "BBN" criteria, and discusses the background of a generic criterion in common usage for nanotechnology, currently denoted NIST-A. The criteria are compared with representative types of research equipment and activities.
Optical tools response to internal vibration that can be excited by the external acoustic environment. The degree to which this occurs depends on many factors, but primarily the correspondence between the resonance characteristics of the tool and the frequency content of the acoustic environment in which it operates. Adverse noise environments, such as those often found in operating laboratories and microelectronics fabrication facilities, can affect the threshold of resolution achievable by the tool. This paper reviews the state of noise specification for optical tools, and the noise levels in typical spaces in which these are intended to operate. Manufacturer's noise specifications often overstates or understates the sensitivity of their tool when the noise sensitivity criterion in oversimplified. More precise and detailed criteria would be useful, for example, in the design of laboratories, or troubleshooting tool operational problems.
The paper discusses two primary areas of interest in a structural evaluation. First, in situ measurements are used to confirm the predicted structural stiffness and resonance frequencies. Second, the evaluation characterizes the manner in which vibrations are propagated through the structure. Methodologies are presented for carrying out these measurements, and typical data are given.
Conference Committee Involvement (1)
Buildings for Nanoscale Research and Beyond
31 July 2005 | San Diego, California, United States