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Pleasanton's Traffic Signals Get Coordinated

Original post made by Stacey, Amberwood/Wood Meadows, on Oct 24, 2008

Traffic in Pleasanton has been a concern for many residents in recent years. Anyone who has tried to drive across town has stories about getting stopped at every light or sitting at a particular light for what seems like an eternity. The idea of synchronizing the traffic lights in order to address these problems has been batted around in the public conscious for quite awhile now. I wondered what the situation was regarding synchronizing Pleasanton's traffic signals. I was a little shocked to learn that Pleasanton's lights are already synchronized. Mr. Mike Tassano, Pleasanton's Director of Transportation, more than obligingly took some time to give a detailed explanation of how Pleasanton's traffic signal coordination works.

The story starts back in 2001 when the cities of the Tri-Valley received funding to upgrade their traffic communication systems. This three million dollar grant allowed Pleasanton to upgrade signal controllers, office equipment, and parts of the main communication network that enabled traffic signal coordination to be possible. Then, in 2002, the first signal coordination began.

For coordination to occur, an engineer creates a pattern that traffic signals along a roadway will follow. These patterns have to take into account such variables as traffic volume, peak hours, intersection size, cycle time, and even the time it takes for pedestrians to cross. The problem with the original coordination patterns put in place in 2002 was a lack of follow-up to see if the patterns were working well.

Within the last two years, Pleasanton's Traffic Engineering department has been giving more attention to optimizing the signal coordination patterns and making sure they're working effectively. Their goal is to get as many vehicles cleared through a green light as possible. This is more daunting than it seems. Pleasanton's streets are not laid out as a grid so signal coordination can get complex. Preference is given to the direction with the most amount of cars and this can change depending upon location. For example, cars pour into the Hacienda Business Park from both directions on Santa Rita Road in the mornings. A driver not following the same path as the rest of this large volume of traffic can end up getting a red light after passing the streets that enter the business park.

Cycle times also play an important role. A cycle is the amount of time it takes for all the lights at an intersection to change at least once. All the signals along a coordinated street need to use the same cycle time. It is this that can cause a driver to feel like they've been waiting at a light for too long. The traffic on a minor street may be light, but the signals still have to be synchronized with the longer cycle time of a major intersection.

To illustrate this, Hopyard Road runs coordinated signals. At the Stoneridge and Hopyard intersection, both are major streets that need about 60 seconds each to let cars through, or 120 seconds total. Further south at Hopyard and Valley Trails, Hopyard needs 60 seconds but Valley Trails only needs about 20 seconds. The intersection still has to use 120 total seconds in order to be coordinated with Stoneridge and Hopyard. That leaves about 40 seconds of extra time which is given to Hopyard. So a driver on Valley Trails could end up waiting for a good amount of time before getting a green light. To alleviate this side-effect of signal coordination, the Traffic department limits the time Valley Trails and Hopyard are coordinated to two hours in the morning and evening.

Several major roadways in Pleasanton see signal coordination active from 7AM until 7PM on weekdays. These are Santa Rita Road, Valley Avenue, First Street/Stanley Avenue, and Hopyard Road. Also, Santa Rita sees coordination from 10AM to 7PM on weekends.

Stoneridge Drive currently does not run coordinated signals. I was surprised to learn that the reason why is because the traffic volume through Hacienda Business Park is too low for coordination to be beneficial. There are not enough vehicles traveling the street's length from 680 to Santa Rita or Santa Rita to 680. Instead, the majority of traffic enters the business park and disperses throughout Hacienda's many side streets. Additionally, the large intersections on Stoneridge have to run long cycle times so that pedestrians can safely cross. Coordinating these would end up causing long and unnecessary wait periods on side streets.

In contrast to Stoneridge Drive, traffic volumes on First Street are too high and the intersections are too small. As a result, traffic signal coordination on First Street provides only limited benefit.

Synchronization is important, but is only a single part of the overall solution to fix Pleasanton's traffic congestion problems. Mr. Tassano gave me his take on what would help relieve traffic congestion. The solutions depend upon the locations. Some locations need larger intersections while in other locations, giving drivers more route options would help. Lastly, newer vehicle detection equipment would allow Pleasanton's traffic engineers to reduce wait times on side streets.

Traffic signal synchronization is an ongoing optimization process that, given enough time and attention, continues to improve. Look for future improvements in signal coordination during the school rush hour.

Comments (8)

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Posted by stop the cut-throughs!
a resident of Downtown
on Oct 26, 2008 at 11:46 am

Stacey,

This is a great election piece, except that Mike Tassano is not running for election. Before you sing his praises so high you should know a few things, most of which he told to me in phone calls and a letter.

The lights on Sunol/First St/Stanley are set to remain green for 2 full minutes in order not to slow down the cut-throughs. Crossing streets, such as Neal, get only 30 seconds of green every two and a half minutes. Rarely can more than one car get through the cycle. That causes those turning from eastbound Neal onto northbound First to blindly fly through the turn in order to avoid another unreasonably long wait. In the past few months there have been two pedestrian accidents at that intersection under those exact circumstances. One time a woman was critically wounded, the next time a mom pushing a stroller was hit.

It has been brought to the attention of everyone up to and including the city attorney that accommodating the cut-throughs, at such high cost to local pedestrians, must stop. Of course, it has not. The lights need to be set up as the light at Montevino -- drive over 25 the light turns red. I will point out that at least Mike Tassano had the courtesy to reply to me. None of my many emails, phone calls or letters has been as much as acknowledged by Hosterman.

I would also like to thank the new police chief for allocating officers to cite speeders and unsafe drivers on this road. It has made a big difference. If we had the response from the mayor's office that I have had from Mike Tassano and Chief Fraser this problem could be resolved. An elected official has a responsibility to ALL of the residents without regard for our vote. I will also note that the Hosterman campaign did send me a letter this year, asking for money.


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Posted by Stacey
a resident of Amberwood/Wood Meadows
on Oct 26, 2008 at 1:10 pm

"The lights on Sunol/First St/Stanley are set to remain green for 2 full minutes in order not to slow down the cut-throughs."

Two minutes is 120 seconds. I guess I wasn't clear in my article that the lights are set to 120 second cycle times. Besides, that is basically what I was told too. Signal coordination along First Street reduces the length of time there is traffic congestion by trying to get the heavier volume of traffic through each intersection over the smaller number of cars on side streets. Waiting longer times at a cross street like Neal is a negative side-effect of the synchronization. I suppose the lights could be un-synchronized so that the traffic congestion lasts more hours than it does now but then people turning at Neal wouldn't have to try to "beat the light". Would that be better?

BTW, the traffic light at Montevino doesn't stop drivers from running it just as such a light wouldn't stop people turning at Neal from flying around the bend. And if you're truly familiar with that part of town, then you'd know that the traffic that used to back up at Montevino now backs up at Bernal and Vineyard instead.


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Posted by stop the cut-throughs!
a resident of Downtown
on Oct 26, 2008 at 1:14 pm

I am not familiar with the Montevino backups. However I do think that having a light go red to punish the speeders would be a good thing. The 120 second timing starts too early in the day, it needs to be only during bona fide rush hour traffic. Even then I would be in favor of reversing the timing -- 120 seconds for cross traffic, 30 seconds for cut-throughs. If we made their commute insanely difficult they might get back on the freeway where they belong!


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Posted by Stacey
a resident of Amberwood/Wood Meadows
on Oct 26, 2008 at 1:44 pm

"If we made their commute insanely difficult they might get back on the freeway where they belong!"

I would agree with you but... One effect the Montevino light has is to discourage traffic taking that route but it only works because there is a viable alternate route called Stanley. Right now there is no viable alternate route for First Street. Many people hope that widening Pigeon Pass and connecting Isabel in with 580 will become the viable alternative. Another part of the problem with First Street/Stanley is that of historic inertia. That route was been there for a very very long time and was the most efficient route by which goods traveled east-west across the valley. The Transcontinental Railroad used to come through too, which helped Pleasanton became a real town. So far there has been no viable alternative that is more efficient than First/Stanley and it is very difficult to provide one. Maybe instead of using the old railroad right of way for downtown parking, we could convert it into a throughway and make the intersections tunnels instead.


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Posted by frank
a resident of Pleasanton Heights
on Oct 26, 2008 at 8:15 pm

Thank you Mike Tassano and others for finally making the Sunol/First/Stanley route very efficient for we who live in Pleasanton and have to commute out and back everyday using this route or portions of this route.

A few years back under the guidance of a previous council and that horrible traffic engineer (who was eventually let go) the experiment was run to achieve the aims of "stop the cut-throughs!". Traffic lights were set to metering. Traffic backed up all the way to 680 and onto 680, creating tremendous hazard for everyone. Pleasanton residents were caught in this disaster. So much grief was created for our own citizens that the council became overwhelmed with complaints. And guess what happened. No more horrible traffic engineer and today we have a sensible traffic flow through this route.

Keep up the good work, Mike. And the traffic flowing......


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Posted by Anonymous
a resident of Highland Oaks
on Oct 26, 2008 at 8:19 pm

Do you really think that would stop cut-thru traffic? Simply restricting traffic on First Street? Do you think that the cut-thru traffic would magically just find their way back to I-580? I believe the City would have done that long ago if that was the case. Unfortunately I don't think traffic works that way. If First Street was run like that then traffic would just make the quick hop over to Main Street and other downtown streets. Or just turn left onto Bernal from Stanley and use Bernal to get to Sunol. Or (worse yet) how about come down Vineyard to Mirador and take that down to Neal and take advantage of that "minute and a half" cross street timing. Much of the so-called "cut thru" traffic is Livermore traffic coming from Stanley anyways, and it's much faster for them to use Pleasanton streets than to work their way to 580. No amount of restricted timing would deter that traffic.

The overall problem is simply too much traffic. Despite what people may think there is no magical "signal timing" solution that can solve it. The freeways cannot handle the volumes of traffic, and the excess traffic that can't be served by the freeways and highways finds its way to main streets. If you restrict the flow on the main streets traffic doesn't go back to the freeway - it finds the "path of least resistance". Many times this path of least resistance is our local streets - residential streets not meant to handle that type of traffic. Plus when that happens excessive speeds occur as cut thru traffic attempts to make up for delays by speeding through these residential streets.

The only option local engineers have is to make sure the main arterials flow as well as possible, so that the excess traffic stays on those streets and away from our local residential streets.


 +   Like this comment
Posted by frank
a resident of Pleasanton Heights
on Oct 26, 2008 at 10:10 pm

Exactly! As I said, keep the traffic flowing, Mike.


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Posted by Stacey
a resident of Amberwood/Wood Meadows
on Oct 26, 2008 at 10:22 pm

I used to harbor a fantasy that the old Iron Trail and Transcontinental Railroad right of ways could be used for part of a Tri-Valley light rail system. That would have rocked. It could bring shoppers downtown and no one has to worry about parking. But supposedly public transit like that requires a certain amount of residential density in order to be worthwhile that the Tri-Valley doesn't have. Plus we have a severe addiction to our SUVS. Buses suck because they're subject to the same road network as all the other traffic.


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