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