Mass Transit Noise Levels and Rider Characteristics in NYC
Preliminary Findings
Richard Neitzel, PhD, CIH Robyn Gershon, DrPHUniversity of Washington Columbia University
35th Annual NHCA meeting, February 27, 2009
Overview
• To assess risk of NIHL from transit noise, data are needed on exposure levels & duration– Levels assessed via dosimetry on NYC transit– Duration assessed via survey of transit riders from
NYC area
Previous research
• Little recent subway noise data– 1931 NYC: 87-97 dBA– 1971 NYC: 87-110 dBA– 1975 NYC: 83-91 dBA– 1996 Calcutta subway: stations 84-87 dBA, cars
72-99 dBA
• Data even more sparse for other mass transit types
Exposure limits to prevent NIHL
75 dBA 85 dBA 90 dBA 100 dBA 105 dBA 115 dBAOSHA >24 hrs 960 480 120 60 15NIOSH >24 hrs 480 151 15 4 0.5EPA/WHO 480 47 15 1.5 0.5 0
Allowable daily exposure duration (min)
Generally assume 40-year lifetime exposure
EPA/WHO is appropriate public exposure limit
% people expected to develop NIHLOSHA - 90 dBA, 8 hrs 25NIOSH - 85 dBA, 8 hrs 8EPA/WHO - 70 dBA, 24 hrs 0
Subway Commuter Rail
Bus Ferry Tram
NYC mass transit types evaluated
26 lines
4 lines
13 lines
Transit noise factors
• Environment– Above/underground
• Location– Vehicle/platform
• Time of day
Noise measurements
• Researchers wore dosimeter– Leq for each measurement
• Multiple measurements per line for each transit type
• Data recorded in measurement log– Time (7 AM to 7 PM)– Location (line, station, vehicle or platform)– Environment (above/underground)
Noise measurements
Platform
• Center of platform
• ~2 min to capture arrivals, departures
Vehicle
• Center seats of vehicle
• ~10 min to capture travel and stops
Noise levels by transit type6
57
07
58
08
59
0L
eq
(d
BA
)
Subway Tram Bus Commuter Rail Ferry
(n=168) (n=32)(n=4) (n=4)(n=28)
(N=243 measurements)
Noise levels by transit type6
57
07
58
08
59
0Le
q (d
BA
)
Subway Commuter Rail Tram Bus Ferry
Platform Vehicle
Noise levels for subway and commuter rail
65
70
75
80
85
90
Leq
(dB
A)
Aboveground Underground
Station Vehicle Station Vehicle
Subway Commuter Rail
05
10
15
20
EP
A/W
HO
dos
e (
%)
Aboveground Underground
Car Platform Car Platform
EPA/WHO noise dose for subway
Measurement lengthCar ~10 min
Platform ~2 min
EPA/WHO allowable daily exposure durations for subway
02
46
81
0A
llow
able
EP
A/W
HO
dur
atio
n(h
rs)
Aboveground Underground
Platform Car Platform Car
Ridership survey methods
• Survey data collected (N=923)
• Modified street-intercept method– Street fairs in NYC
• 40-item, anonymous questionnaire– Transit use (Subway, bus, train, tram and ferry)– Self-reported hearing health– Hearing protection use
• Exposure duration is time spent riding and waiting for mass transit
Ridership characteristics
• Gender– Male (46%)
– Female (54%)
• Age– Mean = 42.3 yrs
• Ethnicity: – Hispanic (15%)
– Non-Hispanic (78%)
– Missing (7%)
• State of residency– NY (95%)– NJ/CT/PA (5%)
• Race– White (66%)– Black (14%)– Asian (6%)– American Indian/Alaska
Native (1%)– Other/Missing (13%)
Ridership by transit type
Subway, 34%
Subway + Bus, 18%
None, 18%
Subway + Rail, 16%
Bus, 2%
Subway + Rail + Bus, 8%
Other combinations,
3%
Rail, 1%
% of 923 respondents
Ridership exposure duration
Subway + Rail + Bus + Ferry, 4.0
Rail + Bus, 3.6
Bus + Ferry, 3.5
Subway + Rail + Ferry, 3.4
Subway + Rail + Bus, 3.1
Subway + Bus + Ferry, 2.3
Subway + Rail, 2.1
Subway + Bus, 1.6
Subway, 1.1
Bus, 0.6Rail , 1.1
Mean hours riding/day
Ridership exposure duration
Transit users dichotomized:
• “Heavy users” (n=188)– Upper quartile– 18.3 hours or more per week
• “Non-Heavy Users” (n=190)– Lower quartile– 5.8 hours or less per week
Hearing protection and transit use
• 31% report muffled or distorted hearing half the time after riding– Heavy users >2.5x more likely to report at least
some of the time; OR = 2.6 (CI = 1.66-4.08)
• 86% never/almost never wear hearing protection while riding or waiting– Heavy users 2x more likely to wear at least some of
the time; OR = 2.1 (CI = 1.16-3.72)
Hearing and transit use
• 41% rated hearing as fair or poor
• 24% said others complained about their hearing ability
• 8% frequently hear ringing, whistling, or buzzing in their ears– Heavy users 2.5x more likely to report hearing
ringing or buzzing half of the time; OR = 2.5 (CI = 1.10-5.63)
Conclusions
• Leq for all transit types >70 dBA
– NIHL possible for some given daily duration
• Leq differed significantly across transit types
• Underground Leq levels highest
• Manhattan Leq levels highest
– Subways, commuter rail, buses
• Vehicles generally <platforms
Conclusions
• Subways– Highest vehicle and platform Leq levels
– Transfer stations louder than local stops; additional contribution from subway musicians
Conclusions
• Next step: estimate NIHL risk by combining exposure level and duration data for survey participants– Create estimate of annual transit noise exposure– Use ISO 1999:1990 to predict NIHL for survey
cohort
Acknowledgements
• People– Muhammad Akram, PhD– Martin Sherman, PhD – Lori Magda– Julie Pearson– Halley Riley– Tara McAlexander– Oliver Merrill– Maxwell Montgomery– Allison Canton– Marina Zeltser
• Funding– NIEHS, grant number
RES 015347A– Department of
Sociomedical Sciences at the Mailman School of Public Health at Columbia University
Appendix: number of noise measurements
Transit Type System Lines Vehicle Platform Vehicle PlatformSubway MTA 26 1 2 1 2
PATH 4 -- -- 1 2
Commuter rail LIRR 3 1 2 1 2SIRR 3 1 2 1 2Metro North 3 1 2 1 2
MTA Bus 13 14 total 16 total -- --
Ferry 1 2 2 -- --
Tram 1 2 2 -- --
Aboveground Undergroundn measurements per line