NOISE TEST-RESILIENT WHEELS MASSACHUSETTS BAY TRANSPORTATION AUTHORITY GREEN LINE

This document presents the results of noise and ground-borne vibration measurements made for three rail transit vehicles operating on the Green Line of the Massachusetts Bay Transportation Authority (MBTA). The purpose of these measurements was to assess the noise and vibration performance of Sab-V resilient wheels compared with Acoustaflex (resilient) and solid-steel wheels, both in current use on the Green Line of the MBTA. Two Boeing Light Rail Vehicles (LRV) and one Presidential Conference Committee Car (PCC) were each equipped with a different wheel set: Sab-V, Acoustaflex, and solid-steel, respectively. Noise was measured inside the vehicles in the passenger seating areas and at wayside locations where groundborne vibration was also measured. The data presented in this report include comparative noise and vibration time histories, one-third octave and narrow band spectral analysis, and in-car statistical noise data. This report concludes that 1) statistical noise level data indicate that the high-level intrusive in-car noise was 1.5 to 3.8 dB less for the LRV equipped with Sab-V wheels than for the Acoustaflex-equipped LRV; 2) in-car statistical data show further that the Sab-V equipped LRV was approximately 10 dB quieter than the solid-steel wheel equipped PCC car; 3) wayside noise levels for the LRVs equipped with these two types of resilient wheels showed no significant difference on straight track; and 4) ground-borne vibration level measurements showed small differences in the average of the maximum acceleration levels between cars equipped with the different types of wheels tested.