Downtown Traffic Signals

[musicman]

You know, I think it is probably a lot harder to synchronize lights in a way that will keep every motorist happy than is generally realized.

seemed to work fine in the early 90's with the older hardware. east/west streets now have the train to contend with.

Edited November 12, 2008 by musicman

[Zippy]

I think the rain somehow throws them off.. They work o.k. from time to time, but it always seems when it rains.. you have to stop at EACH intersection..

Then you have an emergency vehicle go through, then everything screwed..

I still like the NS red and EW green.. rather than the silly "rolling" reds and greens..

Think I'll just bike..

[rsb320]

Well, I'm getting ready to hit the road, wish me luck. I just crank up the tunes and don't let it get to me.

I agree Travis normally works pretty good - could've been the weather.

BTW - Lee Brown had lights around the city timed much better. Wonder if anyone took or kept notes?

[Subdude]

I think you're right. At first I thought it would be a pretty simple problem to solve, but then I started thinking about how downtown's streets work. You have 4 different traffic directions, each of which needs a wave of green lights flowing down it simultaneously. I can see setting up 2 waves, say one moving south and one moving west, but when you have to introduce the opposite directions everything falls apart.

Not only that, but cars and buses accelerate and brake at different speeds, as do individual drivers. Traffic flow varies throughout the day, which changes the amount of vehciles trying to get through an intersection at any given moment and the overall rate of traffic flow. Even synchronizing lights in one direction given changes in traffic volume would be difficult; trying to accomplish it in four directions across all of downtown would likely be impossible.

[memebag]

Not only that, but cars and buses accelerate and brake at different speeds, as do individual drivers. Traffic flow varies throughout the day, which changes the amount of vehciles trying to get through an intersection at any given moment and the overall rate of traffic flow. Even synchronizing lights in one direction given changes in traffic volume would be difficult; trying to accomplish it in four directions across all of downtown would likely be impossible.

Synchronized lights can regulate the speed of traffic. The real issue is meshing the ripples of two orthogonal waves.

Hmmm. Now that I think about it that way, it could be a sort of alternating standing wave. I need to write a simulator.

[musicman]

BTW - Lee Brown had lights around the city timed much better. Wonder if anyone took or kept notes?

and about a yr or so before the 1997 election to rebuild downtown streets, the timing suddenly became worse so that the proposal would have a better chance of passing.

[rsb320]

Travis flowed pretty smoothly this morning. It must have gotten out of synch due to severe weather the previous night. I noticed guys wearing reflective vests, at intersections this morning, taking notes on clipboards. They were obviously observing the traffic flow. They looked more like young mathematicians rather than stereotypical Public Works employees.

Exiting downtown on Milam yesterday was also greatly improved.

[JLWM8609]

Synchronized lights can regulate the speed of traffic. The real issue is meshing the ripples of two orthogonal waves.

Hmmm. Now that I think about it that way, it could be a sort of alternating standing wave. I need to write a simulator.

Simulator eh?

http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=139.0

Have fun!

[memebag]

Simulator eh?

http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=139.0

Have fun!

That's cool, but I want to write one that's for a grid the size of downtown Houston, not just a single one-way street.

[Houston19514]

and about a yr or so before the 1997 election to rebuild downtown streets, the timing suddenly became worse so that the proposal would have a better chance of passing.

Election to rebuild downtown streets???

[musicman]

Election to rebuild downtown streets???

part of a larger bond initiative but one thing supporters were touting was that the issues with the downtown synchronization could be addressed if this passed.

[Geoff8201]

If this change sticks I'm surely going to miss seeing all the lights turn green at the same time, then slamming on the gas and hitting 60mph to try to get through all of them in one go

[rsb320]

This week marks the one year anniversary of the light sychronization change. The lights work fine at off-times but they've still never figured out how to get traffic moving at peaks.

[HedwigTramp]

I hate the "improved" traffic lights in downtown peak traffic.

I take Louisiana (north) in the evening (5pm ish) and it is a nightmare. At every green light I advance 1 block (maybe two) before having to stop to keep from blocking the intersection.

That is north/south. East/West across downtown is even worse. The lights are no where near synchronized. Perhaps this causes the N/S jam as unfriendly drivers block the intersections.

On the flip side. Westheimer and Richmond seem to have excellent traffic flow after the changes.

[JoeR]

This week marks the one year anniversary of the light sychronization change. The lights work fine at off-times but they've still never figured out how to get traffic moving at peaks.

Years ago during rush hours when traffic was congested, all the North/South signals and all the East/West signals were opposite colors and traffic was able to move quickly and safely in all four directions without any complicated timing problems. The speeds were greater than posted limits, but I'm betting that there were fewer accidents because everyone knew that the curb lanes were essentially turn lanes and through traffic avoided them. The safety issue with increased speeds is a sham - the real issue is reduced income from reduced traffic citations. The real solution to most of Houston's problems is to move and find work elsewhere.

[kylejack]

I hate the lights. The old way was much better and allowed you to do a zigzag pattern to get across town if you needed to go diagonally (which was typical for me). The new system only works well on certain streets, like Travis.