City Freeway Teardowns: More on Their Way?

[agentsteel53]

Timing the signals to allow for steady progression of traffic neatly solves the problem of "stopping every 2ft on surface boulevards".

explain most boulevards and arterials in practice, then.  Mira Mesa Blvd here in San Diego has supposedly expertly timed lights, and while the speed limit ranges from 40-55mph, I challenge anyone to drive its length (5.6mi, give or take a tenth) in less than 15 minutes.

[vdeane]

Seriously, who wants to stop at lights every 2ft on surface boulevards?

Its just a few extra minutes to your drive, come on! 

I mind the sitting doing nothing more than anything else.  Especially since the 97 Accord has a first model hydrolic clutch that doesn't like to be held down.

[froggie]

explain most boulevards and arterials in practice, then.

I'd argue that most boulevards and arterials are not properly timed.  There's also the situation where they may be timed, but traffic (for whatever reason) is going much faster than the speed they're timed at.  Portland Ave in Minneapolis, for example, has a 35 MPH speed limit, signals timed at 37 MPH, but drivers tend to go 45-50, even though it means they'll be hitting the next red light.  This on a city street, mind you.

Bottom line:  drivers don't give a $#!+.

[realjd]

explain most boulevards and arterials in practice, then.  Mira Mesa Blvd here in San Diego has supposedly expertly timed lights, and while the speed limit ranges from 40-55mph, I challenge anyone to drive its length (5.6mi, give or take a tenth) in less than 15 minutes.

I'm not a civil engineer, but here's my understanding of it. Timed lights where they cycle in sequence so people don't have to stop really only works on sets of one-way streets. When they time a road like Mira Mesa Blvd., they're optimizing not just for through traffic but for other traffic coming onto and off of the road. The goal is to minimize delays across the entire system. What make a smooth ride for traffic driving the entire length can potentially cause nasty traffic in surrounding areas.

[Grzrd]

Possible scenario:
I-10 above Claiborne torn down and "boulevardized";
I-610 changed to I-10;
Current I-10 from current western I-10/I-610 interchange to Claiborne re-designated as I-49 instead of an I-x10.

One of so many reasons why this "Claiborne Boulevard" concept is a horrible idea. Have I-49 start north by going due south...yeah, right.
Anthony

above quotes from Exit numbers on Future I-49 Corridor thread.

I have cited several times on this forum what could be done to allow for Claibourne to be restored.  For simplicity, here it is again:
- Rebuild both I-10/610 junctions.
- Add a 3rd lane each way on the connection between I-10 West and the Crescent City Connector.
It's technically feasible and would still provide an all-freeway route to/from the bridge.

One ripple effect of the I-10 teardown would be the possibility of creating an I-49 New Orleans "fishhook" to be a cousin of the I-64 Norfolk "fishhook".  Great care would have to be taken with the I-49 signage in order to not confuse the tourists. 

[The High Plains Traveler]

Seriously, who wants to stop at lights every 2ft on surface boulevards?

Its just a few extra minutes to your drive, come on! 

I mind the sitting doing nothing more than anything else.  Especially since the 97 Accord has a first model hydrolic clutch that doesn't like to be held down.

Not to channel Click and Clack here, but that's why your transmission has a neutral position. Not sitting with the clutch pedal depressed will also make your throwout bearing last longer.

[agentsteel53]

I mind the sitting doing nothing more than anything else.  Especially since the 97 Accord has a first model hydrolic clutch that doesn't like to be held down.

if I'm coming up to a light, the first thing I do is take the car out of gear and coast to a stop.

[agentsteel53]

The goal is to minimize delays across the entire system.

more freeways, then.

[myosh_tino]

Regarding synchronizing lights, 19th Avenue in San Francisco used to (maybe it still does, I dunno) have it's signals timed for 30 MPH (I believe the speed limit was 30 also at the time) and going northbound it worked pretty well as long as you could maintain 30 MPH.  Apparently timing lights for a certain speed only works in one direction because trying to go southbound on 19th Avenue was a stop-and-go fest.  It didn't matter how fast you were going, you were guaranteed to miss every other light.

They're also trying to sync the lights on Santa Clara County expressways (Lawrence, Central, Montague, San Tomas) but I seem to have the same problems I saw on 19th Avenue (good one direction, horrible the other).  Is that the nature of timed or synced signals?

[tdindy88]

Could it be a rush-hour thing, where the direction of travel is good for the direction that most of the traffic is heading? For instance, most people go south on such and such highway in the evening, so the traffic lights work well for that direction, but not for the northbound, and vice versa in the morning.

[Bickendan]

No. It's exceptionally difficult to have free-flowing traffic in both directions with synced signals. These work best on one-way grids.

[Zmapper]

Google tells me that it is only about 3-4 miles from I-610 to Downtown New Orleans. I count four major roads, Broad, Galvez, Claiborne, and Rampart. Each road has about 2 lanes in each direction, and considering only 300,000 people live in New Orleans, what exactly is doom-and-gloom concern about? It isn't like you can't take another parallel road, considering there are four of them within about 1.5 miles.

[Brandon]

Timing the signals to allow for steady progression of traffic neatly solves the problem of "stopping every 2ft on surface boulevards".

explain most boulevards and arterials in practice, then.  Mira Mesa Blvd here in San Diego has supposedly expertly timed lights, and while the speed limit ranges from 40-55mph, I challenge anyone to drive its length (5.6mi, give or take a tenth) in less than 15 minutes.

That's probably because they have protected left turn signals at every intersection.  If done right, a boulevard should look like Telegraph or Eight Mile around Detroit.  No left turns - go to the U-turn area, two cycles per intersection for the signals.  It makes the timing easier and faster.

[Revive 755]

Secondly, surface boulevards are not all that bad.  Timing the signals to allow for steady progression of traffic neatly solves the problem of "stopping every 2ft on surface boulevards".

The coordination usually comes at the expense of long waits on the cross streets.  If the jurisdiction in question does not use lead/lag or Dallas left turn phasing, the coordination may only work for one direction in a peak hour.

An at-grade boulevard replacing the Claiborne would also have a few six point intersections east of St Bernard Avenue; those things almost always run poorly.

[Brandon]

explain most boulevards and arterials in practice, then.

I'd argue that most boulevards and arterials are not properly timed.  There's also the situation where they may be timed, but traffic (for whatever reason) is going much faster than the speed they're timed at.  Portland Ave in Minneapolis, for example, has a 35 MPH speed limit, signals timed at 37 MPH, but drivers tend to go 45-50, even though it means they'll be hitting the next red light.  This on a city street, mind you.

Bottom line:  drivers don't give a $#!+.

Actually, drivers do give a shit.  Drivers, as it has been noted by quite a few engineers, will drive a road at what the road feels safe at, not an arbitrarily posted speed limit.  If the road feels safe at 45, then the road should either be posted at 45 or made to feel safe at 35.  With actuated signals prevalent, we've taught drivers that it doesn't matter how fast or slow they go, they may not make the next signal.  We've also taught them, with four-way stop signs at every intersection in some areas, that they might as well speed between them to make up for lost time.

[vdeane]

No. It's exceptionally difficult to have free-flowing traffic in both directions with synced signals. These work best on one-way grids.

I've seen it done on NY 332.  I even treat the road as a freeway because it's so rare to get a light red.  But it must suck for cross traffic - come at the wrong time, and you'll sit at a red for two minutes just to get ten seconds of green time.

[agentsteel53]

I've seen it done on NY 332.  I even treat the road as a freeway because it's so rare to get a light red.  But it must suck for cross traffic - come at the wrong time, and you'll sit at a red for two minutes just to get ten seconds of green time.

sounds like a road that might be converted to RIRO with U-turns for Michigan left and Michigan straight.

[kphoger]

I'm not a civil engineer, but here's my understanding of it. Timed lights where they cycle in sequence so people don't have to stop really only works on sets of one-way streets. When they time a road like Mira Mesa Blvd., they're optimizing not just for through traffic but for other traffic coming onto and off of the road. The goal is to minimize delays across the entire system. What make a smooth ride for traffic driving the entire length can potentially cause nasty traffic in surrounding areas.

Precisely.  We have a serious, ingraned habit of thinking along these lines:
I got a bunch of red lights in a row.  OR...
My line of traffic got a green light, and right away the next light turned red.  OR...
I can never make it through this section without hitting a red light.  THEREFORE...
The stoplights are not timed well.

In short, we assume that how the timing affects our one movement is a good guage of how well the system is designed.  It never occurs to us that optimizing traffic flow does not equal optimizing every movement of said traffic.

[lamsalfl]

I usually wait a few days, let the posts build up and then check back in.  Looks like there is some serious opposition to my opinion.  I just think I know a little bit more about this area since I've lived here my whole life, have seen the traffic flow thousands of times, etc.  That's cool, you're all welcome to your own opinions.

[flowmotion]

Portland Ave in Minneapolis, for example, has a 35 MPH speed limit, signals timed at 37 MPH, but drivers tend to go 45-50, even though it means they'll be hitting the next red light.  This on a city street, mind you.

Having lived in Minneapolis, my take is this is because almost none of the thoroughfares there have timed lights, and the local yokels haven't been trained properly. (For example, drive down Lake St. and watch the lights turn red just as you drive up to them.)

On the other hand, I can name numerous streets in San Francisco where drivers lug along at say 29MPH to hit the 30MPH timed lights. In fact, downtown Mpls drivers do this too.

[Perfxion]

FM1960 in Houston is supposed to be timed at 45 MPH, but either the road is clear and everyone is doing 60MPH hitting all red lights, or gridlock traffic(more of the norm) and everyone is hitting every red doing 5 to 10 MPH. Personally, if a road is a freeway, keep it a freeway. Not every major road needs to be a freeway, but freeway roads are needed.

[bulkyorled]

I know I'm late here but I can't imagine them getting rid of freeways anywhere. Sure you get the nature back a bit or you make it more low profile but then you've just got a diaper load of more issues. Freeways are still the present and the future. In LA anyways...

[TheStranger]

On the other hand, I can name numerous streets in San Francisco where drivers lug along at say 29MPH to hit the 30MPH timed lights. In fact, downtown Mpls drivers do this too.

IIRC, the most notable of those streets in SF is Great Highway's 35 MPH or so light timing, though it's on a stretch with no cross streets, just crosswalks at where the street junctions would've been.

[brownpelican]

Google tells me that it is only about 3-4 miles from I-610 to Downtown New Orleans. I count four major roads, Broad, Galvez, Claiborne, and Rampart. Each road has about 2 lanes in each direction, and considering only 300,000 people live in New Orleans, what exactly is doom-and-gloom concern about? It isn't like you can't take another parallel road, considering there are four of them within about 1.5 miles.

And they all go through not-so-desirable neighborhoods with ridiculously high murder and other crime rates. Do you REALLY want to drive on those streets? Through those neighborhoods?

[bugo]

US 71 in Kansas City is a perfect example of why we shouldn't be tearing down freeways.  While a freeway wasn't torn down, a proper one wasn't built and now there's a deadly stretch of road in the middle of a perfectly safe freeway.  The neighborhood it goes through is split in two even more than it would be if a full freeway had been built, and the noise and exhaust gases that cars sitting at lights emit are polluting these neighborhoods.  Serves them right.  It would be karma if every last one of them got cancer from exhaust gas.  They have blood on their hands from all the fatal accidents on this stretch of highway.