Do HOV lanes actually cause MORE air pollution?

Question

Very few people are in a position to carpool - either you live very close to someone you work with, AND share identical schedules, or you don't. If you don't, the extra driving out of your way to go to your friend's house offsets any savings from going the rest of the trip.

So at most, an HOV lane results in 8% of drivers carpooling instead of 4%.

Because there are so few of them, it's clear sailing through the HOV lane - say it saves them 20 minutes each.

But everyone else is crowded into one fewer lane. Everyone else's commute takes 5 or 7 more minutes than it would if the HOV lane were just opened up to all users.

Do the math - - on an average 45 minute commute, 5 minutes extra times 90% of drivers, versus 10 minutes saved times 10% of drivers, plus the entire 45 minutes saved times the incremental 2% of drivers who carpool who otherwise wouldn't......

On those assumptions, HOV lanes actually increase pollution.

Answer 1

Well if people keep refusing to carpool, of course they won't work.  Look up the term Slugging.

Also, some areas allow hybrids and other efficient cars to use the HOV.

Ok assume you have a 30 minute commute like mine.  Say a coworker lives ten minutes away from you.  This means one car running for 40 minutes instead of two cars running for 30 (60).  That's 20 minutes of gas saved, one less car in traffic, and less wear on the other car.  It makes even more sense economically if there are tolls and such.

Another likely situation: I live 45 minutes from work, and a coworker lives 15.  True we live 30 minutes apart, but if they're somewhat on the way to work, it doesn't matter.

Answer 2

Interesting.

But you forgot to consider that the correlation between speed and emission is not completely linear. Optimum speed for the most efficient use of gas is around 55 mph. The higher the speed, the shorter the commute, but also the lesser the efficiency of gas expent.

So even though you spend less time driving when you drive faster, you are not necessarily saving on gas.

Edit: Okay James, I'm not speaking only from what I hear though. Here's what I've noticed: With my truck I drove 55 miles with each cubic inch loaded with everything I've ever owned, inlcuding a mini-fridge and a 20 inch tube tv and seven suitcases, pots, pans, everything... I drove that thing at 55 mph and my truck burned HALF the gas it would have if I was driving my normal 75 mph WITHOUT the 700+lbs of cargo. =)

Edit (to your response): There is no correlation between time on the road and your car running; neither of those variables are dependent on the other. You are arguing that the longer the car is on the road (indep variable), the more gas the car will burn (dep variable). I am reminding you that this correlation is not completely linear; there are other variables involved including speed and driving stlye that may postively or negatively affect the relation between time and amount of gas burned.  In other words, your assumptions neglect to consider those facts. Above, I should have used the phrase gas burned in place of emission.

The time a car spends on the road only has moderate influence on the amount of gas burned. You need to consider the speed and the driving style which affect the efficiency.

Answer 3

If you've noticed the speed in HOV lanes it can average over 75 MPH.  This IS, contrary to what other people have said, using twice as much gas as going 55 MPH.  There is NO REASON a car would get better gas mileage at 75 than 55 - especially the El Camino that someone mentioned.  The reason is simple - Drag.  Wind resistance increases in proportion to the SQUARE of your vehicle's speed.  Therefore, to be mathematically correct, you're using 1.86 times as much fuel to maintain a speed of 75 mph as you are a speed of 55.  Of course this is offset somewhat by  your reaching your destination a little sooner, but it is still using considerably more fuel overall.

Answer 4

Do the math.  In most areas HOV lanes are used by 60% of commuters.  They transport far more people than the other lanes.  As for people who just won't bus or car-pool, understand that if all those people wizzing by you in the HOV lane were in their own car, you commute would be even slower.

Answer 5

A lot of what makes a efficient or not is in the basic design of the car when it was engineered. The 1972 El Camino I used to own got 22mpg at 65 to 70 mph, while at 55 it would only get 18mpg. In city stop and go never more than 55 it got about 16mpg. So this car was way better on mileage at 70 than at 50. My current car, a 69 bug gets about 37 mpg at 70 and 29 at 55, so it is also better at speed than it is in tight traffic. Most people do not check for themselves and instead just take the word of the media who know less than they do.