The highway toll lanes that have been popping up in other parts of the Bay Area, notably Interstate Highway 880, debuted on the Peninsula on Feb. 11 after years of construction.

Now, drivers are faced with a dizzying array of signs and lane markings on U.S. Highway 101 between state Route 237 in Mountain View and Whipple Avenue in Redwood City.

Part of the Bay Area Express Lanes program, the newly designated toll lanes are the latest way that transportation agencies are trying to manage traffic congestion.

From 5 a.m. to 8 p.m. on weekdays, these lanes can be used for free by carpools of three persons or more, vanpools, motorcyclists and buses. Vehicles with two passengers, who used to take advantage of carpool lanes, won't get a free ride anymore -- and neither will clean-air vehicle drivers. Those two groups will have to pay half of the toll price to use an express lane.

Anyone using an express lane, even those who don't need to pay a toll, will have to have a FasTrak toll tag with them.

By charging tolls on segments of the local highways, transportation leaders expect to be able to manage the volume of vehicles in express lanes, keeping it low enough for drivers to achieve a minimum speed of 45 mph, according to the Santa Clara Valley Transportation Authority (VTA).

Those toll prices will change as traffic congestion changes, rising with increased traffic to discourage some budget-conscious drivers from using the lanes, and then decreasing with less traffic to incentivize more drivers to jump in.

The express lanes in north Santa Clara County were created by restriping existing single carpool lanes on Highway 101 between routes 237 and 85 and on Route 85 from Grant Road to the Highway 101 and Route 85 interchange. New signage, monitoring technology and barriers were also added.

The existing double carpool lanes on Highway 101 from the Route 85 interchange to the San Mateo County line in Palo Alto were both converted to express lanes.

The local express-lanes project broke ground in March 2019, two years after Senate Bill 1 was signed into law. SB1 is investing $54 billion over a decade to fix roads, freeways and bridges across California. Of that state funding, $220 million is going to San Mateo County’s current express lanes segment, and $33 million is helping to fund VTA’s latest segments.

"The integration of managed express lanes will reduce congestion all along the U.S. 101 corridor. It will encourage carpooling and transit ridership as well as the use of technology to help manage traffic," Toks Omishakin, Caltrans director, said in a video about the project.

Construction of additional express lanes is continuing, with lanes being extended north, up from Whipple Avenue to Interstate 380, and south on Highway 101 to Interstate 880.

A Q&A about the new express lanes

The following information comes from Caltrans, VTA, 511.org and the San Mateo 101 Express Lanes Project.

Tell me again what hours the express lanes are in effect?

The express lanes will operate from 5 a.m. to 8 p.m. on weekdays. Unlike the former HOV lanes, express-lane rules cover most of the day, not just commute hours.

So can electric vehicles still use the express lanes for free?

Nope. Customers driving clean-air vehicles, such as cars that run on fuel cells, battery or plug-in hybrids that have a valid clean-air vehicle decal from the Department of Motor Vehicles, will qualify for a 50% discount on tolls. But you'll need to have a FasTrak CAV toll tag in your car to get that discount or you'll be penalized.

How many people have to be in my car for me to use the express lanes for free?

Three or more, unless you ride a motorcycle, in which case you can use the lanes without paying a toll. But again, you've got to have a FasTrak Flex tag on you, otherwise the overhead cameras will photograph your license plate and send you a bill, which will be the toll plus a penalty fee. Before you start your car, make sure your FasTrak Flex tag button is set to position "3+."

And what about a two-person carpool? Can I use an express lane?

Yes, you will qualify for a 50% discount on tolls. But you'll need to have a FasTrak Flex toll tag in your car to get that discount or you'll be penalized. Before you start driving, make sure your FasTrak Flex tag is set to position "2."

OK, so anyone can use the express lane, but they may have to pay. How much does it cost to take an express lane?

That depends on how far you're going. The toll could be 30 cents or several dollars. You'll see the toll for traveling through a zone listed on the overhead electronic sign when you hop into an express lane. For example, if you get into the express lane at Oregon Expressway in Palo Alto going south to Route 85, you will pay one price, and if you continue on Highway 101 to Route 237, you'll pay more. Both toll prices will be listed on the electronic sign at Oregon Expressway.

In addition, toll prices change based on how much traffic is on the road, so you might be charged more to take the express lane from Oregon Expressway to Route 85 on Monday at 8:30 a.m. than you are on Monday at 2 p.m.

What if I'm driving in an express lane, and because of traffic congestion, the toll changes?

If the toll amount changes while you are in the lane, you pay the toll posted when you first entered.

How are the tolls charged?

An overhead antenna will read FasTrak transponders in vehicles and the correct toll will be automatically deducted from prepaid FasTrak accounts.

What happens if too many cars get into the express lanes and the traffic slows way down?

When a lane gets too crowded and cars are traveling slower than 45 mph, the electronic signs will replace the toll price with the words "HOV ONLY." This indicates the lane cannot take any more toll-paying vehicles. Only carpools and other toll-free eligible vehicles are allowed to enter the lane when the signs say “HOV ONLY.” If you're already in the lane when this happens, you can stay in the lane.

How are penalties assessed if I'm in an express lane without a FasTrak tag?

A violation-enforcement system camera will capture a license plate image if a vehicle is in an express lane without a FasTrak tag. FasTrak will send the registered vehicle owner a violation notice for the toll amount and a $25 penalty. If you fail to pay that promptly, then the penalty goes up to $70.

What about the $491 penalty for driving solo in a carpool lane -- is that still being enforced?

Yes. If a California Highway Patrol officer sees you driving solo in an express lane but your FasTrak tag is set for two or more people, you will be pulled over and cited for the carpool violation, which is $491. Your FasTrak setting will be shown on electronic panels on the highway.

I don't get this whole FasTrak tag thing. Which FasTrak tag do I need? How do I get one?

Go to the FasTrak web site for information, including how to order a tag.

Which segments on Highway 101 still have non-toll carpool (HOV) lanes?

South of Route 237 in Mountain View and north of Whipple Avenue in Redwood City.

I'm still confused. Who can answer my questions?

For an overview of the Bay Area Express Lanes project and how to use express lanes, you can watch Caltrans' explanatory video.

For more information about how express lanes work, go to the 511.org website.

For more information about the VTA Express Lanes Project, you can go to Silicon Valley Express Lanes website or contact VTA’s Community Outreach Department at 408-321-7575 or (TTY) for the hearing-impaired at 408-321-2330 or at community.outreach@vta.org.

For more information about San Mateo County’s express lanes, visit the San Mateo County Express Lanes web page.