Do Boston-area drivers drive more efficiently?

[hotdogPi]

The capacity of a road in the United States is about 2100 vehicles per hour per lane. Driver behavior affects this somewhat – it's 2600 in Europe. I'm wondering if that 2100 is actually slightly higher in the Boston area. Here are two pieces of evidence:

This thread lists the busiest 2-lane roads. As you can see, very few states have any over 30,000 AADT. While that list only gives one per state, Massachusetts has at least three (data is pre-COVID): MA 125 between I-495 and the New Hampshire border in Haverhill, MA 12 in Leominster, and US 3 just south of I-95 in Burlington. While having traffic in the middle of the night would increase AADT without decreases caused by congestion, none of these roads would seem to have this, so it's either caused by more efficient drivers (my hypothesis) or every other state 4-laning anything that gets anywhere close to 30,000.

My other piece of evidence is that most of the country has left lane hogs, you know, the ones that stay in the left lane of a freeway going the speed limit or even under the speed limit. That doesn't happen here. There are slow drivers, but they stay in the right lane. Trying to be a left lane hog will get you run over. In addition, the law that trucks must stay in the right two lanes of a freeway is pretty well followed.

Does anyone else have any evidence to support or reject it, or have comments about any other part of the country (or world)?

[SectorZ]

The problem is, those three stretches of roadway are pretty terrible at peak hours. US 3 at the Woburn/Burlington border is a slog much of the day, MA 12 in Leominster has significant backups all day, and MA 125 in Haverhill in the evening is absolute gridlock.

All of these roads I have cycled in during peak traffic and I can easily outpace the traffic, in Leominster over a stretch of two miles (I used to live in Fitchburg so it was a common occurrence for me). I would not consider them efficient at all. Some with less traffic, like MA 38 in Woburn I can outpace traffic from Winchester to Wilmington, a four-mile stretch. And I'm no speedster...

And one refute on trucks, on the eight-lane freeways, where trucks must stay out of the left two lanes, in reality they only stay out of the far left.

[Rothman]

Hm.  Congestion as "efficiency."  Interesting concept.

[hotdogPi]

Hm.  Congestion as "efficiency."  Interesting concept.

This is actually true. The maximum flow on a freeway happens at about 35 mph; I'm not sure what it is on two-lane roads.

[GaryV]

When I first moved to Metro Detroit a few decades ago, I noted that we have rush hours and traffic jams. We're just not sensible enough to slow down for them. 70 mph with only 1 car length separation. That must be "efficient".

[Rothman]

Hm.  Congestion as "efficiency."  Interesting concept.

This is actually true. The maximum flow on a freeway happens at about 35 mph; I'm not sure what it is on two-lane roads.

By only one definition of efficiency.  If it's taking me twice as long to get somewhere, but capacity is maximized at a lower speed, that's not my sense of efficient.

[skluth]

Hm.  Congestion as "efficiency."  Interesting concept.

This is actually true. The maximum flow on a freeway happens at about 35 mph; I'm not sure what it is on two-lane roads.

By only one definition of efficiency.  If it's taking me twice as long to get somewhere, but capacity is maximized at a lower speed, that's not my sense of efficient.

All other things being equal, twice as many vehicles on a road filled to maximum capacity can cross the same point at 70 mph than traffic moving at 35 mph. All other things aren't equal, but the real world rarely matches the theoretical best.

[webny99]

Hm.  Congestion as "efficiency."  Interesting concept.

This is actually true. The maximum flow on a freeway happens at about 35 mph; I'm not sure what it is on two-lane roads.

By only one definition of efficiency.  If it's taking me twice as long to get somewhere, but capacity is maximized at a lower speed, that's not my sense of efficient.

All other things being equal, twice as many vehicles on a road filled to maximum capacity can cross the same point at 70 mph than traffic moving at 35 mph. All other things aren't equal, but the real world rarely matches the theoretical best.

Pointing out the somewhat obvious here, but one of the things that isn't equal is that following distance increases at higher speeds. Another is that higher speeds are harder for entering traffic to match.

[tylert120]

I worked in Boston for 8 months. I'm just here to say Boston drivers may be "efficient,"  but they are definitely some of the worst drivers in America.

[hotdogPi]

I worked in Boston for 8 months. I'm just here to say Boston drivers may be "efficient,"  but they are definitely some of the worst drivers in America.

This makes some sense. Running a red light repeatedly while only cutting someone off 10% of the time you do so will reduce congestion on the roads on average, but that 10% will definitely be remembered as bad driving by whoever else was in the intersection at the time. (And the tradeoff here isn't worth it, due to more likely crashes.) The same is true for aggressive left turns from parking lots onto busy roads, which, unlike running a red light, isn't illegal.

[Rothman]

I worked in Boston for 8 months. I'm just here to say Boston drivers may be "efficient,"  but they are definitely some of the worst drivers in America.

Meh.  CT is worse.

[Amtrakprod]

I worked in Boston for 8 months. I'm just here to say Boston drivers may be "efficient,"  but they are definitely some of the worst drivers in America.

No Turn On Red signs are seen as optional to many. Which is really frustrating for people who design roads. So, now we add in things to force people to make turns very slowly.


iPhone

[MATraveler128]

I worked in Boston for 8 months. I'm just here to say Boston drivers may be "efficient,"  but they are definitely some of the worst drivers in America.

The problem is that Boston drivers drive way faster than they should. US 1 north of Boston basically becomes like the Autobahn during peak travel times, because there may be someone in a tricked out Civic zigzagging between cars. 

[RobbieL2415]

I worked in Boston for 8 months. I'm just here to say Boston drivers may be "efficient,"  but they are definitely some of the worst drivers in America.

Meh.  CT is worse.

There are drivers here that will merge onto the freeway at 55mph and then immediately camp in the center or left lane at that speed. It's obviously out of instinct.

[kalvado]

Hm.  Congestion as "efficiency."  Interesting concept.

This is actually true. The maximum flow on a freeway happens at about 35 mph; I'm not sure what it is on two-lane roads.

By only one definition of efficiency.  If it's taking me twice as long to get somewhere, but capacity is maximized at a lower speed, that's not my sense of efficient.

But it minimizes required pavement and somewhat reduces gas consumption
Actually, 35 is pretty unstable as at that point things can collapse to congested flow to a total loss of throughput, but lower speeds (not speed limits!) during rush hour definitely help to handle more traffic.

[Rothman]

Hm.  Congestion as "efficiency."  Interesting concept.

This is actually true. The maximum flow on a freeway happens at about 35 mph; I'm not sure what it is on two-lane roads.

By only one definition of efficiency.  If it's taking me twice as long to get somewhere, but capacity is maximized at a lower speed, that's not my sense of efficient.

But it minimizes required pavement and somewhat reduces gas consumption
Actually, 35 is pretty unstable as at that point things can collapse to congested flow to a total loss of throughput, but lower speeds (not speed limits!) during rush hour definitely help to handle more traffic.

See my first sentence again.

[kalvado]

Hm.  Congestion as "efficiency."  Interesting concept.

This is actually true. The maximum flow on a freeway happens at about 35 mph; I'm not sure what it is on two-lane roads.

By only one definition of efficiency.  If it's taking me twice as long to get somewhere, but capacity is maximized at a lower speed, that's not my sense of efficient.

But it minimizes required pavement and somewhat reduces gas consumption
Actually, 35 is pretty unstable as at that point things can collapse to congested flow to a total loss of throughput, but lower speeds (not speed limits!) during rush hour definitely help to handle more traffic.

See my first sentence again.

Well, let's separate "efficiency" as defined by Rothman-the-Driver and as defined by Rothman-the-DOT-employee.
There is really a point where improving individual efficiency costs too much for everyone. That can include direct cost of pavement, indirect things like environmental and society implications and so on. A lot of discussions about "should we build this and that" actually come down to that balance in some way.
So while I am not too willing to accept 35 MPH highway cruise speed as new normal (for interstate grade road, maximum throughput is 45-50 MPH anyway), going as low as speed limit on Northway may be a sort of accepted deal.   

[skluth]

Hm.  Congestion as "efficiency."  Interesting concept.

This is actually true. The maximum flow on a freeway happens at about 35 mph; I'm not sure what it is on two-lane roads.

By only one definition of efficiency.  If it's taking me twice as long to get somewhere, but capacity is maximized at a lower speed, that's not my sense of efficient.

All other things being equal, twice as many vehicles on a road filled to maximum capacity can cross the same point at 70 mph than traffic moving at 35 mph. All other things aren't equal, but the real world rarely matches the theoretical best.

Pointing out the somewhat obvious here, but one of the things that isn't equal is that following distance increases at higher speeds. Another is that higher speeds are harder for entering traffic to match.

I've been in enough rush hour traffic in large cities to know your statement is only true as far as safety goes, not real world experience. It also leads to lots of fender benders, but the safe distance between vehicles in rush hour traffic and the reality of rush hour traffic distance spacing are two entire different values. Spacing also (theoretically) becomes a lot less important if we transition to fully autonomous vehicles.

[kalvado]

Hm.  Congestion as "efficiency."  Interesting concept.

This is actually true. The maximum flow on a freeway happens at about 35 mph; I'm not sure what it is on two-lane roads.

By only one definition of efficiency.  If it's taking me twice as long to get somewhere, but capacity is maximized at a lower speed, that's not my sense of efficient.

All other things being equal, twice as many vehicles on a road filled to maximum capacity can cross the same point at 70 mph than traffic moving at 35 mph. All other things aren't equal, but the real world rarely matches the theoretical best.

Pointing out the somewhat obvious here, but one of the things that isn't equal is that following distance increases at higher speeds. Another is that higher speeds are harder for entering traffic to match.

I've been in enough rush hour traffic in large cities to know your statement is only true as far as safety goes, not real world experience. It also leads to lots of fender benders, but the safe distance between vehicles in rush hour traffic and the reality of rush hour traffic distance spacing are two entire different values. Spacing also (theoretically) becomes a lot less important if we transition to fully autonomous vehicles.

While 2 seconds is recommended timing, numbers for free flow traffic are given as 45 vehicles per lane-mile. That is 1.3 seconds at 60 MPH on average, or 2400 vehicles per hour.  You're probably thinking congested flow, where speed cannot be maintained.

[webny99]

Hm.  Congestion as "efficiency."  Interesting concept.

This is actually true. The maximum flow on a freeway happens at about 35 mph; I'm not sure what it is on two-lane roads.

By only one definition of efficiency.  If it's taking me twice as long to get somewhere, but capacity is maximized at a lower speed, that's not my sense of efficient.

All other things being equal, twice as many vehicles on a road filled to maximum capacity can cross the same point at 70 mph than traffic moving at 35 mph. All other things aren't equal, but the real world rarely matches the theoretical best.

Pointing out the somewhat obvious here, but one of the things that isn't equal is that following distance increases at higher speeds. Another is that higher speeds are harder for entering traffic to match.

I've been in enough rush hour traffic in large cities to know your statement is only true as far as safety goes, not real world experience. It also leads to lots of fender benders, but the safe distance between vehicles in rush hour traffic and the reality of rush hour traffic distance spacing are two entire different values. Spacing also (theoretically) becomes a lot less important if we transition to fully autonomous vehicles.

If you're saying that spacing doesn't increase at higher speeds, I don't buy that at all. You might have traffic following too closely at a range of different speeds, but too close at 35 mph and too close at 70 mph are still very different things. Even if it following distances are still "too close" at higher speeds, meaning it's no safer, there's simply no way the average following distance doesn't increase as speed increases.

[spooky]

I worked in Boston for 8 months. I'm just here to say Boston drivers may be "efficient,"  but they are definitely some of the worst drivers in America.

Meh.  CT is worse.

CT is worse. My take was always that MA drivers are fearless, CT drivers are reckless.

[Rothman]

I worked in Boston for 8 months. I'm just here to say Boston drivers may be "efficient,"  but they are definitely some of the worst drivers in America.

Meh.  CT is worse.

CT is worse. My take was always that MA drivers are fearless, CT drivers are reckless.

Amen, brother.

[froggie]

I worked in Boston for 8 months. I'm just here to say Boston drivers may be "efficient,"  but they are definitely some of the worst drivers in America.

Meh.  CT is worse.

Disagree.  CT drivers, like NY, are predictable.  MA drivers are anything but.

[formulanone]

I worked in Boston for 8 months. I'm just here to say Boston drivers may be "efficient,"  but they are definitely some of the worst drivers in America.

Meh.  CT is worse.

CT is worse. My take was always that MA drivers are fearless, CT drivers are reckless.

Miami: "Why not both, plus ignorant?"

[Rothman]

I worked in Boston for 8 months. I'm just here to say Boston drivers may be "efficient,"  but they are definitely some of the worst drivers in America.

Meh.  CT is worse.

Disagree.  CT drivers, like NY, are predictable.  MA drivers are anything but.

Nah.  I grew up in MA.  CT drivers give a bad name to the entire Northeast.  Keep an eye out for those telltale blue plates and you'll see how they've infected everywhere with their overinsured bad driving.