Double carpool lanes planned on 101 | May 4, 2012 | Palo Alto Weekly | Palo Alto Online |

Palo Alto Weekly

News - May 4, 2012

Double carpool lanes planned on 101

Effectiveness of carpool lanes depends on where they're located

by Sue Dremann

Double carpool and new toll lanes are planned for 570 miles of freeways throughout the nine-county Bay Area by 2025, a move that Bay Area transportation authorities hope will help ease congestion as the region grows in population and jobs.

The $3.6-billion regional plan includes changes that will cover all of U.S. Highway 101 in Santa Clara County, Interstate highways 80 and 880 in the East Bay, and Interstate highways 680 and 580 in Pleasanton, Dublin and Livermore, said John Goodwin, Metropolitan Transportation Commission spokesman.

On 101 in Palo Alto and Mountain View, a 2.6-mile stretch of double carpool lanes in each direction is expected to open in 2013. The expansion will start at state Highway 85 and stretch to Oregon Expressway.

But at least one University of California Berkeley study calls into question the benefit of carpool lanes, finding that carpool lanes are only negligibly efficient. The average travel-time savings was 1.7 minutes over 10 miles, with the median at 0.7 minutes, researchers Jaimyoung Kwon and Pravin Varaiya wrote in their 2007 study, "Effectiveness of California's High Occupancy Vehicle (HOV) system."

Kwon was formerly at the Department of Statistics at California State University in Hayward and is now tech director at AOL, and Varaiya is a professor at the University of California Berkeley Department of Electrical Engineering and Computer Sciences.

After taking random 10-mile samples based on Caltrans traffic data, the researchers noted most carpool lanes failed Caltrans' goal of 5 to 10 minutes in saved time. Only 15 percent of these routes offered savings of 5 minutes, and only 7 percent offered 10-minute savings, they found.

Many carpool lanes accommodate fewer vehicles, going at slower speeds, than they would if they were kept as general-purpose lanes, the researchers asserted. That may seem counterintuitive, but it's because slow carpool drivers block the faster drivers behind them. Kwon and Varaiya found that carpool lanes carry only 1,600 vehicles per hour per lane at an average speed of 45 mph, compared with a capacity of 2,000 vehicles traveling at 60 mph — a 20 percent capacity deficit, the study noted.

Carpool lanes do reduce overall congestion slightly, but only when the regular lanes are congested. And there is no evidence that carpool lanes encourage carpooling, which has been in decline, according to Kwon and Varaiya.

Goodwin said while he might not argue with the general premise of the research, he cautioned that one could only draw those conclusions broadly.

"In individual corridors, that's not true," he said. "The 34-mile stretch of Morgan Hill to the San Mateo County border on northbound Highway 101 is the most heavily used carpool lane in the Bay Area," he said, citing Caltrans 2010 raw data.

During the northbound morning commute, the carpools saved 17 minutes over non-carpoolers along the corridor. That savings is a 43 percent increase over 2009, when it was 12 minutes, Goodwin said.

Officials estimate that a highway lane should be able to carry about 2,000 vehicles an hour. The existing carpool lane on 101 from Highway 85 to Oregon Expressway is currently at 86 percent of its capacity — or 1,730 vehicles — during the peak hour, he said. That's significantly above the average 1,400 for any Bay Area carpool lane during the peak hour, he said.

Still, not all carpool lanes are effective, said Dan Collen, deputy director of infrastructure development at the Santa Clara County Roads and Airports Department. Along county expressways, certain segments of the diamond lane have been removed when studies found the designation hampered traffic flow. Lawrence Expressway north of Highway 101 used to have a carpool lane, but county engineers decided to convert it back to general-purpose use, he said.

"We found it was used but was dominated by non-HOV violators, in part because of the need of users to get in the right lane to Highway 237," he said.

But at San Tomas Expressway, the carpool lanes do well. And on north-south routes, they fill a gap where freeways are absent, and traffic volume is high, he said.

In Santa Clara County, a region that could grow by nearly 513,000 residents and 427,000 jobs between 2010 and 2035, according to the Association of Bay Area Governments, transportation officials must squeeze the maximum capacity out of the existing highway system, Goodwin said.

"The era of freeway construction is behind us. It is going to be about expanding capacity. We're not going to see another Interstate 280," he said.

Adding to the capacity means additional carpool and FasTrak toll lanes for single-occupant vehicles, and other traffic-flow measures, such as metering lights, he said.

By 2020, the stretch of Highway 101 from Santa Clara County to Morgan Hill will have double carpool lanes in both directions, and one of those lanes is expected to be converted to a toll lane, Goodwin said.

A high-occupancy toll lane, or HOT, gives people driving solo access to carpool lanes for a fee. Tolls are collected either by license plate readers or through a transponder that can clock the miles traveled in the lane. The tolls increase and decrease as traffic density and congestion within the tolled lanes changes — known as congestion pricing. Carpools and buses drive in the lane at no charge. Actual rates have not yet been determined, but could range from 14 cents to $1 per mile. On Interstate 680, express lanes currently charge $3 for 14 miles during peak travel time, according to the Metropolitan Transportation Commission.

Kwon and Varaiya recommended strategies such as double carpool lanes. Part of the traffic-flow problem with single carpool lanes is because of so-called "snails" — slower drivers who force faster carpoolers to dart back into the regular lanes during peak commute times to try to pass.

As volume in carpool lanes increases, there are more snails, leading to a drop in speed, they wrote. Double carpool lanes would allow carpoolers to get around slower drivers and still be in the fast lane.

A 4-mile section at state Highway 237 and Interstate 880 opened as a test toll lane on March 20.

Staff Writer Sue Dremann can be emailed at


Posted by Good idea!, a resident of Another Palo Alto neighborhood
on Apr 30, 2012 at 10:30 am

Good idea!

Posted by 72 million dollars?, a resident of Adobe-Meadow
on Apr 30, 2012 at 10:41 am

Where is this $72 million dollars coming from? If the VTA is paying for it, I assume the money is coming from local sales taxes. Boondoggles like this are why are local sales taxes are so high and why local merchants are going out of business.

Studies have shown that building more highways does not work. In the short term, new highways encourage people to move farther away from their jobs. In the long term, all those extra commuting miles cause more traffic over longer distances. The $72 million dollars is just a down payment on higher gas prices and greater air pollution.

And remember that this $72 million is on top of the $100 million they just spent on those useless new "merging lanes" along Hwy 101 in Palo Alto and Menlo Park.

Posted by @ 72 million dollars?, a resident of Another Palo Alto neighborhood
on Apr 30, 2012 at 10:50 am

This is part of the Santa Clara County portion of the auxiliary lanes project. On the southbound side, VTA and Caltrans is adding an auxiliary lane between Embarcadero Road and San Antonio Road, and again south of the second Rengstorff entrance. But they are not fixing the insane short entrance/exit merge at Charleston and adding an entrance from San Antonio Road onto 101 South, with a merge lane between that and the Rengstorff exit. So South Palo Altans won't benefit from an improved Rengstorff interchange with southbound 101.

Apparently, Mountain View doesn't want to close the dangerous Charleston onramp onto south 101 and replace it with a ramp from San Antonio Road. (They want Palo Alto cars going by their big box stores near 101.) And Palo Alto didn't fight hard enough for this change.

Posted by Stupid Idea, a resident of Another Palo Alto neighborhood
on Apr 30, 2012 at 10:52 am

What a huge waste of money. I agree with all the good points that "72 million dollars?" made.

Posted by coooper, a resident of another community
on Apr 30, 2012 at 10:53 am

It's probably part of the future conversion of carpool lanes to revenue-generating Lexus lanes.

Posted by 101 commuter, a resident of Old Palo Alto
on Apr 30, 2012 at 10:58 am

I travel 101 South each workday. I'd like to see an exit lane for Embarcadero/Oregon. Cars getting on 101 going south from University stay in the right lane instead of merging into the other lanes and this creates a very slow exit for those of us getting off at Embarcadero/Oregon. We need a separate lane! Thanks for letting me vent. I know it won't happen.

Posted by Highways-Move-People, a resident of Another Palo Alto neighborhood
on Apr 30, 2012 at 11:03 am

> Studies have shown that building more highways does not work.

Really .. care to cite a few sources.

By the way, do you use highways to get where you are going, or do you take "mass transit"?

Posted by OK so it's not funny!!, a resident of Another Palo Alto neighborhood
on Apr 30, 2012 at 11:10 am

All these carpool lanes finally got my over 40 year old son to marry. He and his new Bride carpool along H.85 to work. With the backup of traffic on H.85, that's the only way they can get to work!!!

Carpool lanes are good for love and marriage even at $72 Million!!!!

Posted by Brendan, a resident of South of Midtown
on Apr 30, 2012 at 11:28 am

This has changed the insane Charleston sb entrance for the a big way! I see this heading towards a major accident in the near future and recommend that everyone avoid it. Silly expenditure or not, this change is DANGEROUS...

Posted by Allen Edwards, a resident of Old Palo Alto
on Apr 30, 2012 at 11:46 am

I travel 101 north to just north of SFO a couple of times a week. It has been just wonderful to see the progress they have made in improving the traffic flow with fairly simple changes. It has made a huge difference. Now the projects are moving into our part of the world and that is great too. It is always interesting that some people do not appreciate the progress that is slowly made that makes our collective lives better year after year. As pointed out, there are other changes that would be nice and I hope to see them implemented as well some day.

Posted by mocars?, a resident of Community Center
on Apr 30, 2012 at 11:50 am

What they need is an entrance for SB between Oregon and San Antonio.
Like just before the old Ford plant.

Posted by paloaltotreewatch, a resident of Palo Alto Orchards
on Apr 30, 2012 at 11:53 am

a big problem with the traffic at Shoreline is that when they redid the overpass they took out the true cloverleaf entrance/exit that was there.
It is a major reason there is backup there.
A true cloverleaf entrace/exit is a thing of beauty that functions without the need of a single traffic light.

Posted by KP, a resident of South of Midtown
on Apr 30, 2012 at 11:54 am

Why don't they continue the carpool lanes past RWC all the way to the City? That would make more sense than doubling up on carpool lanes here!
And yes, the Charleston entrance/Rengstorff exit is a b!#@h already! That must be what the right lane ending (with the cones) is part of right after the Rengstorff exit is. What a mess!

Posted by Resident, a resident of Another Palo Alto neighborhood
on Apr 30, 2012 at 11:55 am

I agree completely with Brendan.

SB Charleston on ramp merge is a disaster waiting to happen! It has always been poor now it is idiotically dangerous!

Posted by Southbay commuter, a resident of Another Palo Alto neighborhood
on Apr 30, 2012 at 1:00 pm

Do we need another carpool lane? During my commute hours the carpool lane moves well while everyone else is stuck in traffic.

Posted by rem, a resident of Adobe-Meadow
on Apr 30, 2012 at 1:47 pm

rem is a registered user.

Yep, I AGREE with Brendan/Resident,a resident of Another Palo Alto neighborhood and KP:::

The Charleston entrance/Rengstorff exit is a b!#@h already. Less that a 100 FEET between the ON and OFF ramp..

I would LOVE to close one or the other one. In the late fifties (1950s/early sixty (1960s) Orlando florida had one (Gore ave "on ramp"/South St "off ramp") and we had a couple of wrecks a day. Some of them were deadly.. Gore was DOWN HILL and South was UP HILL. They findly wake up and closed the Gore on Ramp..

Hopefully CalTran will wake and close one these!!!!!

Posted by Choice, a resident of Another Palo Alto neighborhood
on Apr 30, 2012 at 8:42 pm

It is an excellent idea! Our family has used this portion of the road for years and it will be a much smoother ride when it is done. Thank you VTA!!
For those of you who are complaining... you can walk to work.

Posted by Donald, a resident of South of Midtown
on Apr 30, 2012 at 9:28 pm

This article is misleading and confusing. There is no way they can widen the freeway for $72 million. In order to widen the freeway they would need to purchase more right of way at an exorbitant cost. What they can do is squeeze more lanes into the existing right-of-way, widen the ramps and convert a regular lane to a carpool lane.

It is obvious that the current funding streams for freeways are inadequate and VTA is slowly beginning a trend towards charging for use. I think they should save years of transition and just make all the freeways toll roads starting as soon as they can.

Posted by BayShoreDriver, a resident of Midtown
on May 1, 2012 at 11:08 am

If you drive or bike on Bay Shore (either side of the highway but particularly on the east side these days), plan for your commute to be impacted for a long time... It was very dangerous biking with my kids in that area this past weekend, where it used to be very safe.

Posted by Bikes2work, a resident of Santa Rita (Los Altos)
on May 1, 2012 at 12:06 pm

The OC Jones construction bid was only $35M. The engineer's estimate was $55M. What happens to the remaining budget?

Posted by Walter_E_Wallis, a resident of Midtown
on May 1, 2012 at 4:26 pm

Walter_E_Wallis is a registered user.

What a marvelous argument for computer commuting. Imagine a 20 step commute from breakfast table to work station.

Posted by Joseph E. Davis, a resident of Woodside
on May 2, 2012 at 11:27 am

Adding more lanes is a good idea, but it does boggle the mind that 3 miles of such can cost $72 million. I doubt that is efficiently spent - we are probably overpaying by quite a bit due to "prevailing wage" (ie, union) laws.

Posted by KP, a resident of South of Midtown
on May 14, 2012 at 10:46 am

Why not just continue the current carpool lane beyond Willow Rd to the City. The carpool lane is never an issue - the non carpool lanes are the backed up lanes...DUH!

Here we are with another stupid person with a budget they "need" to spend and then end up over budget.

I hate stupid people.

Posted by Road Warrior, a resident of Los Altos
on Oct 18, 2012 at 2:36 pm

72 Million? Are you kidding me? To add MORE carpool lanes?

This at a time when states around the country are getting rid of useless carpool lanes, which only cause more congestion, more pollution and wreak havoc on traffic flow.

And let's not forget that the true cost of this project won't be limited to 72 million. I'd love to see an estimate of what the continued traffic will cost in lost productivity and lost tax revenue.

Posted by Shannon, a resident of Mountain View
on Jun 6, 2013 at 4:02 pm

I'd like to see more normal freeway lanes and less carpool lanes.

How often does one really carpool? Not many people live close enough to hop in the car together then head to the same or neighboring job each morning.

Posted by Resident, a resident of Another Palo Alto neighborhood
on Jun 6, 2013 at 4:16 pm

The big problem with the carpool lanes is that the don't go all the way to SFO, which has often been a problem. Most people driving to SFO are carpooling!

Posted by Sally, a resident of Midtown
on Feb 12, 2014 at 12:49 pm

I agree, carpools need to extend all the way to SFO. The reason they don't: San Mateo County residents voted against them way long ago. We need another ballot to address this issue.

Posted by Sally, a resident of Midtown
on Feb 12, 2014 at 12:50 pm

Here's a link regarding carpool lanes in San Mateo. An interesting read.
Web Link

Posted by anonymous, a resident of Duveneck/St. Francis
on Feb 12, 2014 at 1:36 pm

Please keep us posted on developments on this project, PA Online. I am in favor of steps that will make driving on 101 more bearable and move traffic along smoothly.
However, I am concerned about the floated government scheme -- from whom?? State government - Caltrans? - local municipalities?? - regional transportation agency?? - who knows? for TOLL LANES.
I strongly oppose making the carpool lanes in this region into toll lanes requiring Fast Trak. Some of us rarely go over the bridges and therefore don't have Fast Trak and don't particularly want to have to be "in the system." In addition, our tax dollars pay for these costly roadways and now we are supposed to pay for toll lanes, in order to pay high bureaucrat salaries. (I wonder if they wish to transfer the $$$ to pay for the outrageous cost overruns on the new Bay Bridge?!)Caltrans doesn't have a stellar record on THAT project.
I'm not that old but I swear someone told me that after the GG Bridge was to be paid off, there would "never" be any tolls anymore....laugh at that one. Government is like a monster that is threatening to envelop all of us. We taxpayers need to see clear plans and proposals and understand what is being done with our tax dollars to ensure it makes sense.

Posted by resident, a resident of Downtown North
on Feb 12, 2014 at 4:31 pm

The article says the project will be completed in "summer 2013". Did it actually happen, or was $72 million just wasted? You can tell that I don't drive Hwy 101 very often, but I'm sure a chunk of that $72 million came out of my wallet. Money for nothing.

Posted by Henry, a resident of Downtown North
on Feb 12, 2014 at 6:02 pm

The toll money generated from the new carpool lanes will be offered to cities as enticements to cooperate with One Bay Area's (ABAG, VTA, Regional Air Quality Board) land use plans for dense urban infill. This is where the money will come from to reward cities for building stack and pack projects near Caltrain and El Camino bus routes.

Posted by Tired Commuter, a resident of Menlo Park
on May 2, 2014 at 1:58 pm

Are we done yet? Not close to finished as of 5/2/2014.

Posted by hoax, a resident of Downtown North
on May 2, 2014 at 5:10 pm

This story is a hoax. The truth is that Caltrans just stole our $72 million and wasted it. The 2nd carpool lane will never ever be built. This is the same agency that bungled the $7 BILLION new section of the Bay Bridge is is now prentending that the bridge is safe. More of your tax dollars down the drain.

Posted by anonymous, a resident of Duveneck/St. Francis
on May 3, 2014 at 8:59 am

We don't have Fasttrak as we rarely go across the bridges. Now it appears we will have to get that system - yet one more government bureaucracy to be paying into - in order to pay for the toll lanes.

Posted by Joke's on Us, a resident of Community Center
on May 3, 2014 at 10:09 am

Still waiting, will die waiting.

Posted by Michaelquiek, a resident of another community
on Jun 5, 2017 at 10:02 am

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