Ground-Borne Noise and Vibration in Buildings Caused by Rail Transit (2010)

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TCRP D-12 Final Report F-1 APPENDIX F PROBLEM STATEMENTS FOR POTENTIAL FUTURE WORK 1. TOPIC 1 - HUMAN SENSITIVITY TO GROUND-BORNE VIBRATION FROM HIGH AXLE LOAD TRAINS 1.1 RESEARCH PROBLEM STATEMENT One goal of the TCRP D-12 research program, "Ground-Borne Noise and Vibration in Buildings Caused by Rail Transit" was to develop a relationship between rail transit-induced ground-borne vibration/noise exposure and community annoyance. An effort was made in the D-12 study to sample a variety of transit modalities, however most of the data collected corresponded to situations with either light rail or rapid transit operations in urban or suburban areas. Since heavier axle load vehicles tend to generate low-frequency vibration, it is likely that annoyance would be more likely associated with perceptible building vibration than audible noise. Unfortunately, only a small amount of the D-12 data applied to situations where the feelable vibration was sufficiently severe that it could be considered a likely source of annoyance. The D-12 study included two locations where passenger or freight trains powered by diesel- electric locomotives operated in the same corridors as transit systems. However, the amount of data collected for such systems was not sufficient to identify the differences in the vibration characteristics of this type of traffic, or how these operations affected human annoyance. The proposed research would be an extension of the D-12 project and would collect data specifically near alignments where intercity, locomotive powered trains are the predominant source of vibration, for example along the Northeast corridor from Boston to Washington, DC. The additional data would augment the current D-12 data set, extending the type and range of exposure described by the dose-response relationships. The results of the study would help define human response to ground-borne vibration, particularly the relationships between annoyance and total exposure. The data also would assist in refining and standardizing predictions of ground-borne vibration for different types of rail traffic. 1.2 OBJECTIVES The objectives of the research would be, 1) To obtain annoyance and vibration exposure data for a large sample of people who live near rights of way that carry predominantly locomotive powered passenger and freight trains. 2) To develop dose-response relationships for locomotive powered trains and compare these to the curves developed during the D-12 program.

TCRP D-12 Final Report F-2 1.3 RESEARCH PROPOSED The goal of the research would be to obtain at least 1000 respondents to a community survey of annoyance, similar to the survey used in the D-12 program. Task 1 - Identify Systems for Test Identify 3-5 systems for survey and testing. Obtain the support of the Agencies involved, similar to what was done in the D-12 study. Task 2 - Survey of Annoyance Develop and administer a questionnaire to residents who live in the test areas. Task 3 - Field Testing Perform field measurements to characterize the vibration exposure at the homes of each of the survey respondents. Analyze the exposure data using the metrics that were developed during the D-12 program. Task 4 - Dose-Response Analysis Develop dose-response relationships using the survey results and the measured exposure. Compare the relationships to those obtained during the D-12 study. If appropriate, combine the data with the D-12 data to produce a unified dose-response relationship. Task 5 - Report Summarize the results in a final report to include discussions of the implications with respect to currently used criteria. 1.4 ESTIMATE OF THE PROBLEM FUNDING AND RESEARCH PERIOD It is suggested that funding in the range of $250,000-$300,000 would be needed for this work, and the work could be done in 1.5-2 years. 1.5 URGENCY AND PAYOFF POTENTIAL Currently, vibration mitigation is routinely employed in the design of new rail projects. Research in Europe1 finds that annoyance from the predominantly low-frequency vibration associated with high axle load trains occurs at levels higher than the current FTA criteria. Consequently, it is possible that vibration mitigation measures are being needlessly used for new rail projects. With a planned high speed rail project in California, and with plans by Amtrak to introduce high-speed rail service in up to eleven existing corridors, the potential payoff in capital cost savings by reducing the need for vibration mitigation, could be significant. This research would not be considered urgent in the sense that it has no safety or other critical implications. However, given recent economic challenges, it is now even more important to spend public money wisely. 1 Klæboe, R., Turunen-Risem, I.H., Hårvik, L., and Madshus, C. (2003) “Vibration in Dwellings from Road and Rail Traffic – Part II: Exposure-effect Relationships Based on Ordinal Logit and Logistic Regression Models,” Applied Acoustics, Vol. 64, pp. 89-109.

TCRP D-12 Final Report F-3 1.6 RELATIONSHIP TO FTA STRATEGIC GOALS AND POLICY INITIATIVES and TCRP STRATEGIC PRIORITIES The research would address the second FTA strategic goal, "Improving Capital and Operating Efficiencies," by potentially reducing the capital cost of vibration mitigation measures. This could also impact operating costs in terms of ongoing maintenance, and/or replacement of the mitigation means that would normally be necessary over the lifetime of a new rail line. 1.7 RELATED RESEARCH The proposed research is a direct follow-on to the TCRP D-12 project, "Ground-Borne Noise and Vibration in Buildings Caused by Rail Transit." The survey, measurements and data analysis techniques that were developed during the D-12 project would be directly applicable to the proposed research. 1.8 PERSONS DEVELOPING THE PROBLEM This research idea is proposed by the same team who performed the work associated with the D-12 study. Dr. Jeffrey A. Zapfe Director, Noise and Vibration Group Acentech Incorporated 33 Moulton Street Cambridge, MA 02138-1118 Phone: (617) 499-8033 Fax: (617) 499-8074 Email: jzapfe@acentech.com Dr. Hugh J. Saurenman ATS Consulting 801 S. Grand Ave., Suite 575 Los Angeles, CA 90017 Phone: (213) 488-7770 Fax: (213) 488-0270 Email: hsaurenman@ATSConsulting.com

TCRP D-12 Final Report F-4 Dr. Sanford A. Fidell Fidell Associates, Inc. 23139 Erwin Street Woodland Hills, CA 91367 Phone: (818) 884-6775 Fax: (818) 884-8775 Email: sf@fidellassociates.com 1.9 PROCESS USED TO DEVELOP PROBLEM STATEMENT The proposed work represents follow-on research to the TCRP D-12 project. The research would have a direct impact on the work that is conducted by members of the TRB ADC-40 Rail Noise and Vibration sub-committee and the American Public Transportation Association (APTA) Track Noise / Vibration Technical Forum. 1.10 DATE AND SUBMITTED BY

TCRP D-12 Final Report F-5 2. TOPIC 2 - VERIFICATION OF TRANSIT NOISE AND VIBRATION PREDICTIONS 2.1 RESEARCH PROBLEM STATEMENT The current method to predict ground-borne vibration and noise from new transit projects is documented in the 2006 manual, "Transit Noise and Vibration Impact Assessment," published by the Federal Transit Administration (FTA). The detailed prediction methods use the transfer mobility (TM) method to estimate the vibration and noise exposure in communities near planned new rail alignments. Because the TM method uses vibration propagation tests to characterize the ground transmission properties, there is a relatively high degree of confidence that the attenuation of vibration with distance near measurement sites is accurate. However, there are a number of other areas where there is less confidence in the data and the assumptions used for ground-borne vibration predictions. Some of these areas include:  Deriving force density levels from measurements. Experience is that there can be substantial differences in the force densities derived depending on where the measurements are performed.  Vibration attenuation occurring when the vibration energy travels from the ground into the building foundation, commonly referred to as the “coupling loss.” Clearly this depends on the building construction.  Attenuation of vibration as it propagates throughout the building structure, and amplification resulting from resonances of the floors and other structural elements. There are a number of different factors used by different consultants. The experience with measurements performed during the D-12 project is that the average effect of the coupling loss and amplifications for wood-frame residential structures is close to zero decibels; however, there can also be a large building-to-building variation for seemingly identical structures.  The radiated noise efficiency is typically assumed to be 1. That is, the vibration velocity level of the floor is assumed to be equal to the resulting sound pressure level when using the decibel references of 1 µin/sec for vibration velocity and 20 µPa for sound. The data from the residences measured for the D-12 project suggest that a more appropriate adjustment would be -5 dB rather than 0 dB.  In many cases, the resulting predictions are augmented with a factor of safety to account for these uncertainties. A uniform adjustment of 5 decibels is used by many consultants. Others used an undefined “design factor” as the adjustment. The goal is often stated as making sure that the predictions tend to be conservative. That is, the general approach is to make sure that it will be rare that vibration levels from train operations exceed the predicted levels. The results of the D-12 project, “Ground-Borne Noise and Vibration in Buildings Caused by Rail Transit,” show that it is unlikely that more than a small percentage of the variance in human response to ground-borne vibration and noise will ever be explained by physical measures of the vibration amplitude. Extrapolating from the survey data, it appears that there always will be some people who report being highly annoyed by even the faintest vibration and others who are never highly annoyed by vibration regardless of how high the vibration levels are.

TCRP D-12 Final Report F-6 One conclusion that can be drawn from the results of the D-12 study is that basing decisions about expensive vibration mitigation measures on highly-conservative prediction procedures may not be justified. The goal of this study will be to provide information that can be used to standardize the vibration prediction procedures and can be used to develop consistent policy about how much “safety factor” should be included in the predictions. If the study can confirm the accuracy of the prediction procedures or suggest changes that will improve the accuracy, smaller factors of safety could be justified, which could substantially reduce the need for vibration mitigation. Also, analysis of post-build vibration levels could lead to less conservative assumptions about factors such as estimating radiated sound levels from predicted vibration levels. The overall goal would be to provide tools that would result in vibration mitigation being installed only where it is needed. 2.2 OBJECTIVES The objectives of the research would be to, 1) Refine vibration prediction procedures. 2) Provide data that decision makers can use to justify the factor of safety used in vibration prediction studies. 3) Justify the adjustment factors that are used for building coupling loss, floor amplification, and for conversion from vibration level to radiated sound pressure level. 2.3 RESEARCH PROPOSED Task 1 - Identify Transit Systems for Test Identify a representative number (5-10) of new transit systems that have associated pre-build ground-borne vibration and noise predictions. In order to remove the confounding factor of mitigation, it is suggested that test areas be chosen where no track mitigation was installed. As part of the selection process, it should be determined that pre-build vibration/noise prediction data is available for use. Task 2 - Select Test Locations For each of the systems in Task 1, identify possible test buildings and contact the owners in order to obtain permission to make vibration and noise measurements. The goal would be to achieve 50 individual test locations. Task 3 - Field Testing Conduct vibration and noise measurements at each of the test sites. The noise and vibration would be measured simultaneously inside and outside the building for a sufficient number of train passages (typically 15-20). At a minimum, data should be acquired in 1/3 octave frequency bands. Task 4 - Data Analysis Compare the exterior vibration data to the pre-build estimates in order to determine the accuracy of the predictions. Compare the interior and exterior vibration data to determine the building coupling loss and compare this to the recommended adjustments in the FTA manual. Compare the interior noise level to the interior vibration level to determine the vibration-to-noise adjustment factor and compare this to the FTA method.

TCRP D-12 Final Report F-7 Task 5 - Report Summarize the results in a final report to include recommendations related to the use of safety factors, building coupling loss and vibration-to-noise adjustments. 2.4 ESTIMATE OF THE PROBLEM FUNDING AND RESEARCH PERIOD It is suggested that funding in the range of $400,000-$450,000 would be needed for this work, and the work could be done in 2-2.5 years. 2.5 URGENCY AND PAYOFF POTENTIAL Currently, vibration mitigation is routinely employed in the design of new transit projects. If the vibration and noise predictions are overly conservative, then it is likely that mitigation is being specified unnecessarily. Depending on the required mitigation performance, the cost of mitigation could be $100-$500 per foot of track. Given that thousands of feet of track mitigation may be identified on a project, better predictions could represent significant cost savings. This research would not be considered urgent in the sense that it has no safety or other critical implications. However, given recent economic challenges, it is now even more important to spend public money wisely. 2.6 RELATIONSHIP TO FTA STRATEGIC GOALS AND POLICY INITIATIVES and TCRP STRATEGIC PRIORITIES The research would address the second FTA strategic goal, "Improving Capital and Operating Efficiencies," by potentially reducing the capital cost of vibration mitigation measures. This could also impact operating costs in terms of ongoing maintenance, and/or replacement of the mitigation means that would normally be necessary throughout the lifetime of a new transit line. 2.7 RELATED RESEARCH The results from the TCRP D-12 program, "Ground-Borne Noise and Vibration in Buildings Caused by Rail Transit" have a direct bearing on the proposed research. The proposed research would be a natural follow-on to the work undertaken during the D-12 project. 2.8 PERSONS DEVELOPING THE PROBLEM This research idea is proposed by the same research team that was awarded the D-12 study. Dr. Jeffrey A. Zapfe Director, Noise and Vibration Group Acentech Incorporated 33 Moulton Street Cambridge, MA 02138-1118 Phone: (617) 499-8033 Fax: (617) 499-8074 Email: jzapfe@acentech.com

TCRP D-12 Final Report F-8 Dr. Hugh J. Saurenman ATS Consulting 801 S. Grand Ave., Suite 575 Los Angeles, CA 90017 Phone: (213) 488-7770 Fax: (213) 488-0270 Email: hsaurenman@ATSConsulting.com Dr. Sanford A. Fidell Fidell Associates, Inc. 23139 Erwin Street Woodland Hills, CA 91367 Phone: (818) 884-6775 Fax: (818) 884-8775 Email: sf@fidellassociates.com 2.9 PROCESS USED TO DEVELOP PROBLEM STATEMENT The proposed work evolved from the TCRP D-12 project. The research would have a direct impact on the work that is conducted by members of the TRB ADC-40 Rail Noise and Vibration sub-committee and the American Public Transportation Association (APTA) Track Noise / Vibration Technical Forum. 2.10 DATE AND SUBMITTED BY