Contrary to the view in some quarters that mass transit is an unalloyed blessing buses and subways around New York City generate harmful levels of noise.
Using sensitive noise dosimeters, the team of researchers, led by exposure scientist Richard Neitzel from the School of Public Health at the University of Washington and Robyn Gershon, DrPH, an environmental and occupational health scientist and faculty member at the Columbia University Mailman School of Public Health, conducted hundreds of measurements of noise levels at platforms and stations, as well as inside of vehicles on New York City subways (MTA and PATH), buses (MTA), ferries (Staten Island), commuter railways (LIRR, SIRR and Metro North), and the Roosevelt Island tramway.
The scientists found that on average, the MTA subways had the highest noise levels, at 80.4 decibels (dBA), followed by the Path trains, at 79.4 dBA, and the tram, at 77.0 dBA. The lowest average levels measured, 74.9 dBA and 75.1 dBA, were obtained from the LIRR and Metro-North trains, respectively. The very highest levels measured in the study were found on an MTA subway platform (102.1dBA) and at a bus stop (101.6 dBA).
In contrast, the noise level of a whisper is 30 dBA, normal conversation is 60 to 70 dBA, a chainsaw is 100 dBA, and gunfire is 140 dBA.
Regards bus stops: I go out for walks and hate to see a bus approaching. They are louder than just about anything else on the road. Plus, the older ones belch diesel exhaust smoke (the newer ones are built under a tougher regulations and are not as bad). Well, why can't they have better mufflers? Would effective mufflers really cost too much or weigh too much?
Subways are the worst. Again, does it cost too much to make subway stations safe for human hearing? Imagine some corporation generated such noise levels without providing protection. It would get fined and sued. Why do government-owned mass transit systems get away with damaging hearing?
In general, noise levels were significantly higher at platforms compared to inside vehicles for all forms of mass transit, except for ferries and the tram. The borough with the highest mass transit noise levels was Manhattan, followed by Queens and the Bronx. Major hubs were noisier than local stops and underground trains and stations were significantly louder than those aboveground. According to Dr. Gershon, of all mass transit, subways had the highest noise levels, with roughly half of the maximum levels exceeding 90 dBA. "At some of the highest noise levels we obtained (ex. 102.1 dBA on the subway platforms), as little as two minutes of exposure per day would be expected to cause hearing loss in some people with frequent ridership, based upon the International Organization for Standardization models for predicting hearing impairment from noise."
Cars take you from where you want to start to where you want to end up. You can control who you ride with. You can choose a car with very good noise insulation and a quiet engine. Can can choose which music to listen to and do not need ear plugs to listen to it. Granted, you have to drive and pay attention to the road. Cars come with trade-offs. But given the advantages it is not surprising that most people choose to drive.
By Randall Parker at 2009 June 20 11:09 AM Energy PolicyUnderground systems like London and Washington DC are much quieter. So NY can improve. Also, We can hope that buses get quieter with pollution control systems and hybrid systems.
A great deal of noise from old-style diesels has nothing to do with the exhaust; it's the profile of the fuel injection.
Diesel engines must inject, evaporate, and mix fuel with air before it can ignite; when one spot ignites, the increase in pressure causes the remaining premixed fuel to ignite in a pulse. Injecting a lot of fuel before ignition causes the premixed fraction to "knock". This is probably what's causing the racket that annoys you (and me).
Switching to modern common-rail injection systems with piezo injectors and advanced injection profiles will probably damp most of that noise down (except when the engine is cold, which is mostly when it's starting and just leaving the lot in the morning). So would converting to natural gas engines or LPG; any spark-ignition engine will avoid that simultaneous ignition of a premixed charge in normal operation.
Plexiglas "screen" doors between the platform and the track are an easy and cheap way to reduce noise. ~US$3.3 million per platform.. I can't locate any data on the noise reduction specifically in subways but here's some generic data.
Of course, that example is from Hong Kong, where the transit workers are non-unionised ("All work had to be carried out during the daily network downtime of three hours and progress could not impede regular scheduled train services or public access to the trains. This translated to demanding site management and a stringent safety programme for both workers and the public.") and the passengers won't try to break the screen doors deliberately, set them on fire, get into fights and throw their compatriots through them, etc.
(I was also going to mention that platform screen doors should reduce energy consumption from platform climate control systems --- but surprisingly this may not be true).
In Montreal, there seems to be a rule that all bus brakes must squeal at the highest possible volume. I've actually seen people cover their ears and turn away from the ubiquitous ear-splitting shrieks, and there's absolutely no will to do anything about it. Amid all the noise about the environment and improving our quality of life that issues from our municipal government (and, I assume, from those of other cities) there's nary a peep about noise pollution. It's one more large cost of Government action that isn't properly factored in to analyses.
Several bus systems (including the nearby Pierce Transit in WA) run on CNG. They're noticeably quieter than diesel, but still not as quiet as they should be. This seems to work reasonably well with buses, but would be a safety problem with subways. Subways need to be electric.
Especially if these new NG sources actually pan out, converting buses to CNG seems like a no-brainer. It's cost-competitive with diesel, but close. Existing diesel buses can be converted with new heads, but it works better if there's a fleet replacement over a 10-year period, in which time the fleet would have been replaced, anyway.
In Philadelphia, subway stations seem louder than the airport. The solution should be easy -- stick foam on the ceilings and on various surfaces without aesthetic appeal (such as between the tracks, walls between the tracks and platform, etc). Philly subway stations are generally decrepit anyway, so it's not as though there's an architectural reason to not do so. Then again, SEPTA can't balance its books even with $500M in annual government subsidies.
SEPTA buses are loud but don't seem as loud as the subways. Maybe that's because of all the bus-inspired car horns and cursing.
The trolleys aren't loud, but I could get to Center City faster by crawling on my back.
This is, of course, why New York is "the city that doesn't sleep." It's way too noisy.
The reason train stations are loud is simple - underground stations are enclosed. Above ground stations are usually surrounded by walls, screens or adjoining structures (houses, etc.) that contain and reflect noise around the train/bus station. The solution is to either make quieter vehicles using hybrid/electric propulsion or keep passengers enclosed or behind barriers/sliding doors until the vehicle has stopped before letting them approach the vehicle. As to why people choose public transportation versus cars - again it is simple: cost and convenience. I take a noisy expensive plane because it is faster and more convenient than driving long distances. Others take trains into and out of cities because car operating costs such as gas, insurance and of course parking are formidable. Commuting into cities during rush hour can take twice as long as going by train or bus that uses a dedicated highway lane. If you live in a city as many students do, public transportation is the best choice - often at a discount for students. There is no mystery here, The problem is like most problems - one of cost versus benefit. If you can afford a car feel free to do so.
I wonder if we should use ear plugs even at home. Or those active npoise cancelling earphones.
Sometimes I use earplugs to sleep and I feel better, more rested.
BART in San Francisco is noisy as heck.
I want to point out that some cities--like my native Baltimore--have recently acquired hybrid buses that are almost stealthily quiet by comparison with the diesel buses they're replacing. Much more expensive, of course--but worth it?
well, duh.
Anything with a diesel engine is guaranteed to shake itself to decrepitude. That is why buses die after 12 years and are horrible to ride after 5. Light rail vehicles, however, are quieter (to the point of being dangerous to the blind), and they last for decades since they run on electric motors.
Mikey, we get the brake shriek too here in Manhattan, and I cover my ears the same way.
Think of the additional damage to all those who listen to music while riding loud trains or buses, which has to be turned up loud enough to drown out the background noise which is already at the lower range for hearing loss. Another story with noise-cancelling earphones, of course, but one can be sure that the majority of listeners don't have them.
By the way, it would be very difficult (that is, expensive) to fix the NYC subway system as regards noise. Metal wheels without rubber tires and many stretches of track with sharp curves (including inside stations) mean lots of noise even without brake squeal.
David,
Good point about the louder music as people try to hear over subway sounds.
What I wonder: Do noise cancellation headphones work well in subways? In my experience they work well on airplanes. Curious side-effect: You hear more conversations around you. Mostly I see that as a minus. I don't want the distraction.