April 24, 2007

Stupid Bridges of the SouthCoast

Bridge Opening

Brightman Street Bridge Closed to Traffic

Just want to let you folks know the fun it’s been commuting to work lately. Traffic Gripe coming up.

They’ve closed the Brightman Street Bridge for repairs. Repairs are on schedule, but we’re still in the middle of the two week period of time during which the bridge is closed to traffic. This is the bridge that people north of Rte 6 in Somerset use to get to Fall River and points East.

When this bridge is closed, traffic going East must go west and south to Wilbur Ave and get onto 195 East. From there they will use the Braga Bridge to cross the Taunton River.

The approaches to the onramp at Wilbur Ave. are not built for that sort of traffic. This means tons of backup at the intersections anywhere near the onramp. Once you’re past that fun and you’re on 195 E, you’re in for another treat.

There are lane restrictions on the Braga Bridge. And lane restrictions going under Fall River’s Government Center.

And, today, some sort of accident on the highway.

I haven’t timed it, but I’m guessing that my commute has doubled. It’s gotten worse as time has gone on. I wonder if the bad weather was keeping people indoors last week. Now they’re all out and about, clogging the roads.

This gripe brought to you by the Massachusetts Highway Department. We wouldn’t have this problem if they’d finished the new bridge, which was delayed for lack of funds. Where did those funds go? The Big Dig, of course. Ka-ching!

There’s work going on in New Bedford, too, on 195 E. Lucky for me, my commute now includes 195 E in New Bedford. Yay!

Links:

Posted by James at April 24, 2007 8:36 AM
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To alleviate your stress, can you work from home one day a week? A couple of people in my office do this.

Just a thought.

Posted by: Patti M. at April 24, 2007 9:07 AM

I don't think they'll ever finish that damn bridge. How many years ago was it started?

On the plus side if it weren't for the good old Brightman St. bridge with it's stupid semi functioning drawbridge you might have an LNG facility across the river right now.

Posted by: B.O.B. (bob) at April 24, 2007 9:20 AM

That's true, Bob.

I don't ming having to drive out to Wilbur ave. I just wish it could handle the congestion better.

And, I guess, I wish they didn't close the bridge at the same time they close lanes of the Braga bridge.

Left hand, meet right hand.

Posted by: James at April 24, 2007 9:33 AM

Er, I mean "mind"

Posted by: James at April 24, 2007 9:33 AM

I'm guessing the congestion is worse this week because last week was school vacation. Most teachers don't work during that week, and a lot of parents go on vacations or at least take the week off to spend it with their children.

I'm leaving home at 7:15 to make my 8:00 am lecture. Last week that was getting me there ten minutes early, this week I'm making it just on time.

I heard a guy call in to Mike Moran's show yesterday. His idea was that there wouldn't be any congestion on the Braga bridge if people didn't drive in the high-speed lane and then merge on the bridge. Mike pointed out that they'd have to merge SOMEWHERE, and the guy just didn't get it. He just kept repeating his idea.

I think a lot of people have that attitude that people driving in the soon-to-be-closed lane before the merge are evil. As if that lane is invalid far before you ever see the cones. At what point are they not evil? Do you have to merge in before traffic stops, otherwise you're taking an unfair advantage by driving in a perfectly valid lane next to stopped traffic?

I think this is an interesting phenomenon.

Posted by: Maggie at April 24, 2007 11:15 AM

People who continue to drive in the lane that's going away annoy me a lot. When there are multiple signs telling you the lane you are in is going away before any congestion, if you'd get your ass over to one of the lanes that isn't going away there would be less of a problem once the merge occurs (merging at a higher speed instead of trying to sneak in front of someone, stopping them and all the traffic behind them).

That being said human nature will mean a large number of people won't do this no matter what so you get punished by being good and getting over. If everyone merged at the first sign that said "left lane closed 2 miles" then traffic would barely have to slow down.

Posted by: B.O.B. (bob) at April 24, 2007 11:50 AM

Sorry, BOB. You and the caller are both wrong. It's not late merging that slows the traffic down.

There are two optimizations going on: optimal use of the roadway and smoothness of the actual merge.

If everyone merged at the first sign that said "left lane closed 2 miles" then traffic would barely have to slow down.

This would just increase the size of the traffic backup because it reduces the usable road. That's de-optimizing the roadway.

It's easier to suck air through a wide straw than a narrow one. If the straw is narrow, it's easier to suck air through a short one than a long one.

The earlier people merge into the remaining lanes, the more traffic increases. If everyone merged early, it would effectively reduce the capacity of the roadway, as if the lane restriction were larger.

A 3 lane road can support more traffic than a 2 lane road. The longer the 3 lane road remains restricted to 2 lanes, the less traffic it comfortably supports.

(This is why the choice of where to merge for best efficiency isn't just arbitrary.)

For best efficiency, merging should happen at the last possible moment. Not only is merging early not a virtue, it's the opposite.

"Early mergers" have chosen an arbitrary point at which to restrict the lanes, when there already is a well-defined point. Since not all mergers (even early mergers) will agree where this arbitrary point is, there is little chance for optimizing the merge itself (they've already given up on optimizing the roadway). It's chaos.

The real problem with merge optimization is that people don't leave sufficient space in front of them for the merge to occur smoothly. Why don't they do this? Because they're afraid that multiple people (early mergers) will merge in front of them because everyone is deciding where to merge arbitrarily.

If everyone merged at one agreed spot (the actual lane restriction is the logical place to do this) motorists would feel comfortable with a large gap in front of them, and the merge would be smooth.

A decent compromise is for a motorist to allow more gap as he approaches the lane restriction and actually allow the other lane to merge.

However, if people cling to the idea that there is virtue in early merging and that late merging is evil, hope for traffic optimization basically flies out the window because you'll have angry early-mergers trying to spite the people who are doing the right thing by waiting until the last moment.

Some semi-related info:
http://amasci.com/amateur/traffic/seatraf.html

Posted by: James at April 24, 2007 12:37 PM

My observation (based on the work on the Bourne Bridge) is that it works okay either way as long as everyone is doing the same thing. That is, if everyone merges early, that works out okay. Likewise, if everyone stays in their lane and doesn't try to merge until it's time to merge, that works out too (it's a little slower but it's not mayhem). What typically happens, though, is that most people will merge early, then a few people will blow past all the people who merged early and then expect to be given a free cut.

Having said all that, I don't see the point of giving two miles' notice if you don't want people to merge two miles early. There was less mayhem at the Bourne Bridge when they stopped saying too far ahead of time which lane was going to be closed (it varied from day to day). That put everyone in the same boat, so people tended to stay in their lanes until it was time to merge.

Posted by: Julie at April 24, 2007 12:42 PM

PS - the merge situations at the Bourne Bridge were exacerbated by the fact that they also coincided with an on-ramp and a lost lane. So you'd start off with three lanes, then an exit, then you lose a lane (would have been nice to just have that lane BE the exit, but no), merging traffic from Buzzards Bay, and then whatever lane closure was scheduled for the day, all happening within 1/2 mile. Depending on the traffic load, going from three lanes to two was seldom a problem except during tourists' rush hour; even going from two lanes to one wouldn't have been too bad except that there was another lane's worth of people joining us from Buzzards Bay, including people who thought they'd save time by exiting 25, going around the rotary and then merging back on.

(I understand the argument against "de-optimizing the available roadway," but I'm not sure what's the advantage to optimizing it if there's going to be a bottleneck restricting flow anyway.)

Posted by: Julie at April 24, 2007 12:59 PM

The problem with merging at the actual merge is that all lanes are no longer travelling at the same speed. I guess I'm assuming traffic isn't awful to begin with. if there are only 20 cars in a mile of road then a two lane road is just as good as a 3 lane road. If people didn't tailgate constantly then a merge at the last minute wouldn't be a problem. But they do.

Oh, i guess I should have looked at your link 1st. It says the same thing. The only problem is, what happens when 1 person touches their brakes on a highyway? the car behind slows down just enough not to hit that persons bumper. Then they stay there. Hell no they are not going to let someone get in front of them.

So that solution is great except that it will never happen because human nature won't let it happen. So a better solution would be to merge BEFORE traffic slows to a crawl, i.e. when you 1st hear/see/realize that you're lane is going to dissappear. Again it won't happen so the point is moot. You can do nothing about this. Probably the best solution to this is if you know the left lane is going to disappear is to get over to the right lane which will probably have a higher average speed than either the center or left lanes. Or be a jerk and pass everyone on the left. Just don't get upset when no one wants to let you in at the merge.

Oh, and once you're in traffic pick a lane and stay in it. constantly switching back and forth to "faster" lanes only slows everyone down.

Posted by: B.O.B. (bob) at April 24, 2007 1:31 PM

People who merge early can completely stop traffic in their lane. I then some early mergers are afraid of merging, and so give themselves plenty of room to accomplish the feat. Unfortunately, they also inconvenience everybody behind them by making them stop until somebody lets them in. It's this sort of chaos that slows the traffic way down.

But Bob's statement about people being "good" and merging when they're warned that a merge *is coming up* is exactly what I think is interesting. Obviously some people feel this way. I don't think all early mergers are afraid to merge. It's as if you're "causing trouble" by merging where you're told. Or getting a "free ride" in a lane that isn't closed!

One problem that's caused by making the road long and skinny and slow as opposed to short and fat and slow is that the traffic is backed onto the exit and 103. If people had a place to go, then problems on 195 wouldn't cause a backup onto 103.

Posted by: Maggie at April 24, 2007 1:34 PM

Anecdotally, I've seen that when a lane is closed for a long period of time (as happend for a couple of years on the lowell connector that I drove every stinking day) people adjust and eventually traffic barely slows down. I think this is because they know what's coming and adjust their driving. you still had a few people driving the closing lane right to the last second but there were fewer and fewer as time went on.

As far as merging at the 1st sign goes. What do you think they put them there for if not to tell you to start thinking about merging? Just a friendly note saying you might not want to be dialing your cell phone in a few minutes if you don't want to become intimately familar with a jersey barrier?

Posted by: B.O.B. (bob) at April 24, 2007 1:50 PM

First, I want to apologize to BOB because boy my post was jerky. What am I suddenly, the traffic deity? I went to lunch ant took my anti-asshat pills.

Based on what I said, I highly suspect that merging at the point of the lane restriction is optimal.

To answer Julie: optimizing the available roadway reduces the effect of the traffic. The larger the jam gets, the more chance it has to affect side streets and onramps and such.

Ah, I see Maggie addressed this. So, "what she said."

BOB, I agree with your statements about human nature. When it becomes moot, you have some choices.

You can decide that if nobody else is optimizing for best traffic flow, you can try to optimize for yourself. Getting over to the right lane and passing everyone on the left are both ways of doing this (assuming there is nobody in front of you). I think passing on the left is more effective, and I wish there were an understanding of how to do this. Traffic wastes fuel.

Since I consider merging at the lane restriction is optimizing the roadway, I have no qualms merging in there. And I usually have no problem getting back in. It's very difficult to keep out a determined and assertive driver.

But for those who are less confident, look for the person who is on the cell phone -- merge in front of him or her. He doesn't care whether you get in front of him, he's just happy if he's not colliding with someone. Just make sure you don't actually cut him off, because he's not paying much attention.

Getting over to the right is effective on 195 in Providence sometimes, if you can do it early enough. Unfortunately, people are changing lanes in front of you which is disruptive, as BOB points out. Excessive lane changing is one of the big causes of traffic in the first place.

To concede something else, if the left lane is completely clear, I often will not use it to pass everyone, even though I believe it is the right thing to do and even though I know I can easily merge back in. Why? Because often I just don't care.

Posted by: James at April 24, 2007 1:59 PM

I am not familiar with "early mergers" making everyone stop. If everyone has to stop for them, then they're not merging as early as I was thinking.

Truthfully, traffic on my way to work each morning is pretty light (it's much heavier for people going westward), so "early merging" does not require anyone to do anything special. It's just a lane change. I may have to slow down a bit myself to do it, but everyone will be slowing down in a moment anyway, so there's no point in fighting over who gets to be first in line.

But if you're in a situation where your lane change requires the cooperation of others, then it's no longer what I think of as "early merging." I think of that as "needlessly switching lanes during a traffic jam." Either switch early when it's easy or switch at the merge point, but once traffic is at a crawl, you might as well stay in your lane.

Posted by: Julie at April 24, 2007 2:19 PM

And now I'll have my lunch too. Unfortunately, I'm off my anti-asshat pills, so I thank you for your patience.

Posted by: Julie at April 24, 2007 2:21 PM

That's what a hip flask is for.

Posted by: Patti M. at April 24, 2007 2:23 PM

Bazing!

Posted by: James at April 24, 2007 2:28 PM

OK - someone needs to tell my why the phrase "puffy merger" is popping into my head.

Posted by: James at April 24, 2007 2:38 PM

You can blame that on Brian's spell check (that wanted to change my name to puffy merger).

Posted by: Patti M. at April 24, 2007 2:39 PM

Well, I'll just say that the signs say, "merge ahead," which doesn't mean "merge now." I think you're right, Bob, it does mean, "don't dial your cell phone now unless you want a date with the jersey barrier," or whatever you humorously said. It's a warning of what to expect. (Although I think you were being flip. But the idea is that people need to know ahead of time that they're going to have to slow down to avoid an accident. The problem comes if they put the signs up far too early.)

Maybe that's why people get upset -- they interpet it as "merge now," and feel that people who don't aren't following the rules.

Now what really ticks me off is coming home between 3 and 7. Coming home between 3 and 7, there's a sign as you get off the exit onto 103 telling you that you may not take a left turn at the light between 3 and 7. After that, closer to the light, there's another sign which is a left turn arrow with a circle/slash through it. Once again, you may not take a left turn at that light.

Yes, that's really, really inconvenient. There's a big Stop and Shop shopping plaza to the left as well as route 6 and all the glories it has to offer, plus most of Somerset. I'm sure a lot of people think they'll run by the market, or CVS, or maybe they just live over there. But you can't take a left because it would slow traffic down when traffic is already ridiculous.

Yesterday I saw a truck take a left *right in front of a police officer* there, and the officer did absolutely nothing because he was yapping away with two women who'd come over to chat. Earlier I'd seen him blow his whistle at a car and make the driver go straight.

Now I'd like to take a left and get home more quickly (or actually, I needed to go to the market yesterday), and I'll bet 75% of the other drivers would like to take a left, but we don't.

That's clearly breaking the rules and makes an unpleasant situation even worse.

(Julie -- I'm surprised you've never seen the slam-on-the-brakes-and-merge-early behavior. I've seen people bring an entire lane of traffic to a halt because they decide they have to MERGE NOW.)

Posted by: Maggie at April 24, 2007 2:43 PM

Ah, the urge to merge.

Wait--that's not that kind of merge...

Posted by: Patti M. at April 24, 2007 2:46 PM

Traffic wastes fuel.

Yes but if your going faster makes 30 people slow down does that save fuel?

Posted by: B.O.B. (bob) at April 24, 2007 2:50 PM

Like I said, if you have to slam on your brakes, then you're not doing what I had thought you meant by "early merging." Obviously you're dealing with a situation where there's already a jam when the merge is announced, rather than most of the merge situations I deal with.

Posted by: Julie at April 24, 2007 2:57 PM

Using the lanes effectively should allow traffic to flow more quickly. 30 people slow down when people try not to let mergers in; this causes people to hit their brakes and that wastes fuel.

It's another good reason to allow people to merge. I nearly always am extremely generous with people merging in while traffic is moving, even if they're merging early. If traffic is practically stopped, I am not generous at all at letting people change lanes until we are near the merge, when I suddenly become very generous again.

So, I'm doing my part to try to keep people from having to hit their brakes. If they don't return the courtesy to others (or, later, to me) it's really in their hands, not mine. I'm still going to optimize use of the roadway.

So, my generosity merging is hopefully teaching by example. But learnign doesn't seem to happen quickly.

Posted by: James at April 24, 2007 3:14 PM

Julie -- You've just never seen it happen, I guess. I'm talking about people who are nervous mergers, who see that "Merge Ahead" sign and decide to merge, but don't just ease into traffic -- they slam on their brakes and then try to get in. It's hard to get in when you're not moving, and everyone behind them has to stop. I'm not talking about a traffic jam.

Posted by: Maggie at April 24, 2007 3:45 PM

Oh. I call them "crazy people."

Posted by: Julie at April 24, 2007 4:15 PM

LOL. See... you lived away from here too long!!

Posted by: Maggie at April 24, 2007 4:17 PM

I've seen what Maggie is describing, although I don't see it all the time. People who seem to suddenly decide to merge instead of trying to merge smoothly.

Actually, you'll see it a lot on 93 near 24 outside of Boston. Often people don't realize their exit is coming up. That's where I see it the most. But you do see it in lane-restriction merging, too.

Posted by: James at April 24, 2007 4:19 PM

(On EAForums, Florida is the only state which has its own long-running thread about crazy residents.)

Posted by: James at April 24, 2007 4:25 PM

That amazes me. I would have guessed Texas.

Posted by: Julie at April 24, 2007 4:31 PM

As an early merger who doesn't "slam on the brakes", I'd like offer my opinion that merging earlier rather than later is better. Before the actual obstruction requiring the merge, there's more room to navigate, to speed up a little or slow down a little, so as for everyone to sort themselves out and get it together.

The biggest problem, in my opinion, are the folks who are driving all the way down to the obstruction, and then trying to squeeze in then when both space and the patience of their fellow drivers is in short supply. Merging late creates congestion IMHO. It is easier to change lanes when traffic is moving smoothly than it is to change lanes when traffic is bunched up and moving slowly.

Merging early only creates congestion when the yahoo behind you on the left has decided "you're not getting in front of ME" and accelerates the moment you put on your signal. Now you have a quandary, you have to either endanger yourself by cutting the jerk off, endanger yourself by accelerating to get in front of him and then immediately having to step on your brakes to not hit the car ahead of him, or simply drive faster than you should so you can pass the next car on the right and THEN merge. The congestion doesn't occur because people are merging early, the congestion occurs because of drivers who refuse to let people merge.

Personally, if I am alone in my car and the person behind and to the left of me accelerates in response to my left turn signal, I *will* cut them off. That signal means I am about to get in front of you, it's not an "last chance to pass" indicator, it's an indicator that it is now too late to pass.

Posted by: Chuck S. at April 25, 2007 10:56 AM

There actually is a science to traffic flow, but nobody here has referenced or expressed an informed scientific opinion. What's interesting (and upsetting) is the bad feelings that lead to dangerous behavior in this population of uninformed motorists. Both sides (early and late mergers) see the other as inhibiting traffic flow and this can apparently lead to dangerous driving, such as insisting on merging in when the driver doesn't want you to merge (I believe you'd be at fault if he hit you, as you are responsible for changing lanes and the law does specifically state not to change lanes if you can't make it in), or driving to prevent people from merging in (not very nice but legal). I don't know, in Massachusetts, that there are any laws that govern when you merge at road construction. The law says to follow the signs and drive slowly when there's roadwork. I'll repeat that a sign that instructs you to "merge ahead" is not instructing you to "merge now," as you can see which side I fall on the "when to merge" debate. That said I do not cut people off and I do not prevent people from merging in. It's an unpleasant situation all around, and I try to stay away from people coming in off an exit so they can get onto the highway, and I merge in where there's a space or a friendly driver, without bringing traffic to a halt in my lane.

Whatever the science or the law, you have to take other driver's actions and reactions into account when you're driving. Maybe other drivers perceive you as a "jerk" if you drive in the unclosed lane before it closes, but I've never had a problem merging in at the actual merge. OTOH, as Chuck points out, people DO NOT like letting people in ahead of the merge (probably because they're moving and that slows them down and, in their mind, puts them farther back in the queue), and can be very stubborn. IMO, this makes the late merge the better option. As the radio host pointed out, pepole are going to merge eventually.

Another point about the late merge is that traffic is about to start moving. There's a squeeze as the road narrows, but after that the traffic moves more quickly. So the person letting you in isn't paying as much of a perceived price as if they let you in when there's a huge line of slow traffic ahead of them.

Unless someone can point to a scientific traffic flow model or a law telling me that I'm mistaken, I'm going to continue to drive in the way that follows the signage and causes, in my experience, the least trouble for other drivers.

Posted by: Maggie at April 25, 2007 12:09 PM
There actually is a science to traffic flow...

Jim Kaput used to bring this up in the hallway (back when he and I shared the same hallway.) I wish I had a better memory of the particulars.

I've seen simluations of the pressure wave which can result from people not leaving enough space between them and the car in front of them (and the pressure wave last much longer then the anomaly which caused it.) I think James might have even posted something about that here.

I don't recall seeing any merge simulations though. Anyone?

Posted by: Jim at April 25, 2007 12:28 PM

I pasted this link earlier. Here it is again:

http://amasci.com/amateur/traffic/seatraf.html

Posted by: James at April 25, 2007 12:41 PM

Density waves in traffic are very real, and I have read about them in the past. The phenomenon occurs in any large group of objects that move together. I recently heard someone mention a new theory that galactic arms are simply density waves where the stars tend to clump up, as opposed to structures which contain a certain set of stars.

Hard science on merging in traffic? Don't have it.

As James points out with his link above, merging is smoother and quicker when there are large gaps between cars. When traffic is moving smoothly (i.e. ahead of the merge point), the gaps tend to be larger than when traffic is bunched up at the merge point.

It would be nice if everyone would keep a couple car lengths in front of them at the merge point. But in my experience, at the merge point there will be no large gaps, and merging will only happen when someone comes to a complete stop to let someone in, which creates more of a slowdown than simply allowing someone to merge earlier who doesn't want to have to fight his or her way into a traffic snarl.

IMO, if all drivers would merge at-speed early, then nobody would need to *stop* at the merge point, including the driver on the right who drove to the obstruction.

Posted by: Chuck S. at April 25, 2007 12:59 PM

But it's not specifically the merge point that is the problem there. It is the lack of space between the cars that enables the situation. If there are 2 car gaps between every car and someone or even several someones decide to merge at the merge point, no problem.

I think it also has a lot to do with what Maggie was talking about, the 'road rage culture', if you will. I'm right and he's a jerk, so I have to teach him a lesson.

Then again, there are also situations where traffic exceeds capacity. A buffer won't help those.

Posted by: briwei at April 25, 2007 2:21 PM

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