new idea for relief on 281 ? (San Antonio, Marshall: home, schools, cost of)

[TexHwyMan]

The superstreet proposal is actually a variant of the "Michigan Left", which, as the name implies, has been used in Michigan quite extensively and successfully for years. A similar solution actually has been used in San Antonio before-- coincidentally, on 281 between Bitters and Loop 1604 when it was upgraded from a divided highway to a freeway back in the late '80s, and it worked quite well then. Reports at the time indicated that traffic flow improved significantly through the area during construction than it was before.

Originally Posted by Dopo

This person said exactly what I thought when I saw the situation at Evans & 281.
"....one resident said, adding that this is the first plan he’s seen that focuses on solutions rather than profits."

The first time that I saw that area I thought that that situation has been created by somebody that is trying to make money.

Puh-leeze. This is the standard anti-toll rhetoric. What some folks still don't get is this: the toll road plan would build an expressway (with overpasses), which is, of course, what just about everyone agrees is the best long-term solution. The problem is that building a full expressway is very expensive, and tax revenues right now are not sufficient to fully fund such a project. The toll plan was simply a way to pay for the project. It would be owned by the RMA (a government agency), so there would be no "profits". Can we please put this inane piece of propaganda to rest once and for all?

Here's the way I would fix this problem: During rush hour, make the green light on 281 last 4-5 times longer to let the traffic flow

How difficult is it?
Whoever wrote the program for the computer that controls the light, just have to make a few changes to the program to make it run on "Rush hour mode" at certain times.

Do you really think it's that easy? The problem with extending the green phase on 281 is that you build-up much longer queues on the intersecting streets. If you're the person coming on out from Evans, can you imagine having to sit there 4-5 times longer? And then what? Under you plan, Evans would get the same length of green time as now, but have queues that grow 4-5 times longer with each cycle? Not a practical solution.

Originally Posted by TexasWeatherman

It's just horribly planned growth for the highway system up north.

Originally Posted by Sigaven

It's just a horribly planned highway system for the unprecedented growth seen up north. Should've been access roads and overpasses all the way up to loop 46.

Again, this situation is not because of bad planning or a lack of planning. There is a great plan for that area, and that plan is to build a full freeway (this means 6-8 main lanes with overpasses and access roads) all the way to FM 306. The problem is funding it. (And don't call it Loop 46-- the folks along 46 don't want to hear that!! )

Originally Posted by Dopo

You can have 100 lights,
but it's not a problem if they are syncronized and give enough time for traffic to go through.

Lots of people say to just synchronize the lights and the problem will be solved. The traffic volumes and patterns on 281 are such that synchonization is not the panacea that laypeople think it is. Here's an explanation why:

Signal synchronization relies on traffic being broken-up into groups of vehicles called platoons traveling at a steady, predictable speed. I'll use southbound 281 in this simplified hypothetical example. The light on SB 281 at Stone Oak turns green for 1 minute, releasing a platoon of cars. Then it turns red to allow Stone Oak traffic through. As the platoon begins to arrive at Evans, the light there would turn green for about 1 minute, thus allowing that platoon to go through. Then it would turn red just behind the platoon to allow Evans traffic through. The cars that turned onto SB 281 from Stone Oak should get stopped by the red at Evans since the green is timed to allow the mainstream platoon through. However, when there is a heavy inflow of traffic from Stone Oak, all of those cars collectively backup at Evans and there are enough of them to essentially take the place of the next platoon coming down behind them. Therefore, when the light turns green at Evans, the traffic that turned onto 281 from Stone Oak starts through and by the time they clear, the mainstream platoon that came in behind them gets stuck in back of them and ends-up getting caught by the red light. The situation gets even more exacerbated downstream at Encino Rio by the traffic that turns onto 281 at Evans, and the situation in both places continues to compound over time until the volume of inflow traffic drops down to a level that is below downstream capacity. This is why the timing of the signals cannot be improved any more on 281. The only solution would be to progressively increase green times on 281 at each downstream signal, but that then causes even longer backups on those side streets.

Here's a different way to explain it. Imagine I have an assembly line with boxes traveling down it. At three points along the line is a gate that opens to allow each box through, then closes behind it. Each box takes 1 second to go through the gate, and boxes have a 2 second gap between them, so the gates are timed to open for one second, then close for two seconds, then open for one second, and so on. Everything should flow smoothly, right? Well, what happens if I open a side track just downstream from the first gate that inserts an extra box in-between each box? Downstream at the second gate, the timing allows the first box through, but then closes and stops the second box for two seconds. Meanwhile, the next box from the first gate comes down the tracks and hits the back of the box waiting at the second gate. The gate opens to let the first of the two boxes through, and then closes and the next box has to wait. This process continues and and more boxes start backing up at that second gate, right? Well, I can adjust the timing at the second gate to allow two boxes through, but then what happens if I try to open another side track just downstream from there? I don't have any time now to inject a new box into the stream, and even if I could slip one in, now the timing at the third gate is a complete mess and boxes are backing up all the way to the second gate. Furthermore, boxes are now backing-up excessively on the side tracks. This is the same situation with signal timing-- those boxes represent platoons of vehicles, the side tracks are the cross streets, and the gates are the signals. And this example does not take in account the increased complexities of adding traffic from both sides as well as left turns.

Signal synchronization works best on arteries where there is a comparitively light volume of inflow from cross streets, or where the volume of vehicles turning in from the cross streets is roughly equal to the volume of vehicles that turn off the through street and onto the cross street (in other words, they net each other out.) That way, the volume of traffic on the arterial at intersections throughout the corridor is fairly stable. On 281, that situation doesn't exist as, in the morning, nearly all the traffic on the intersecting roads turns onto 281 and very little traffic at the same time turns-off of 281 onto the intersecting roads. In the evening, the problem is that there is heavy left turning traffic as well as a more concentrated peak period than in the morning, so delays compound faster.

[mmac12]

I agree with Dendox and SAAggiemom... I also live in this community and if the timing of the lights at Evans, Stone Oak and Marshall are timed longer , it would give the straight traffic on 281 more time to flow freely. I think it would help alot of the congestion.

[Dopo]

Originally Posted by mmac12

I agree with Dendox and SAAggiemom... I also live in this community and if the timing of the lights at Evans, Stone Oak and Marshall are timed longer , it would give the straight traffic on 281 more time to flow freely. I think it would help alot of the congestion.

That's what I've been saying the whole time

[mmac12]

Sorry Dopo I meant to include your name also!!!

[ChrisSA_wxatUIW]

"THAT IS THE SMARTEST THING I'VE EVER HEARD ANYONE SAY ABOUT ANYTHING!"

I've never heard anyone just break it down like that, and now it makes COMPLETE sense

[TexHwyMan]

Originally Posted by mmac12

I agree with Dendox and SAAggiemom... I also live in this community and if the timing of the lights at Evans, Stone Oak and Marshall are timed longer , it would give the straight traffic on 281 more time to flow freely. I think it would help alot of the congestion.

Perhaps, but at the expense of traffic on Evans, Stone Oak, and Marshall. In the morning especially, that would result in extremely long backups on those roadways.

[SAAggiemom]

That is a totally incorrect assumption. Exiting Encino Rio, Evans, Stone Oak, and Marshall will be much, much easier! This plan was originally used in North Carolina with a great deal of success. It is also used in Maryland. As I said earlier, I've seen the power point presentation three times and I'm convinced it will benefit ALL drivers that travel 281 north.
I just hope they find the funding and get started soon. I hate for them to spend the money for a left hand turning lane at Evans and yank out the Stone Oak fountain when it won't be necessary if the Super Street is built.
***Don't forget the utility construction begins Monday morning on Evans and 281.
Happy Driving!

[ryneone]

Moderator cut: see comment

Originally Posted by SAAggiemom

That is a totally incorrect assumption. Exiting Encino Rio, Evans, Stone Oak, and Marshall will be much, much easier! This plan was originally used in North Carolina with a great deal of success. It is also used in Maryland. As I said earlier, I've seen the power point presentation three times and I'm convinced it will benefit ALL drivers that travel 281 north.
I just hope they find the funding and get started soon. I hate for them to spend the money for a left hand turning lane at Evans and yank out the Stone Oak fountain when it won't be necessary if the Super Street is built.
***Don't forget the utility construction begins Monday morning on Evans and 281.
Happy Driving!

Did this come out of left field?? I see no where where anyone was disagreeing with this proposal.

[Sigaven]

I just hate this whole area of town. That new neighborhood that Pulte is building by the Village at Stone Oak shopping center sickens me every time I look at it. All those trees razed, the blandness of the neighborhood. And then more trees were razed last week, even more hills cut into to put even more bland houses right by Overlook parkway. Do they think that people will actually move into those homes? When the market is practically at a halt?

Anyway, just a semi off topic rant, carry on.

[SAAggiemom]

Ryneone ~ Texhwyman said he thought the S.S. would cause long backups on intersecting streets. I was pointing out that is not the case. I don't know why you thought that was left field. Sorry if I was unclear.