Express lanes and FasTrak

US 101 is the busiest road near Palo Alto and the only one with express lanes. These are the far-left lanes marked "EXPRS LANE" on the pavement, where solo drivers can pay a toll to skip some of the congestion and carpools ride for less or for free. Palo Alto sits right where two separately run systems meet: the 101 Express Lanes in San Mateo County to the north and VTA's express lanes in Santa Clara County to the south.

This page explains where each segment runs, when tolls apply, how a FasTrak Flex tag sets your price and what happens if you enter without one. For exits and driving routes, start with our guide to driving to Palo Alto.

Where the lanes run

For Palo Alto drivers that means continuous express lane options from Mountain View up to South San Francisco, with the handover from VTA to the San Mateo system at the north edge of town. The two systems bill separately, so a long trip shows two tolls on your FasTrak statement. Details are on FasTrak's pages for the San Mateo lanes and the 101 and SR 85 Santa Clara lanes.

Interstate 280 has no express lanes. Elsewhere in the South Bay, express lanes also run on State Route 237 and Interstate 880, both managed under the same FasTrak account system.

When tolls apply

Both segments near Palo Alto charge tolls Monday to Friday from 5 a.m. to 8 p.m., in both directions. Outside those hours and all weekend, the lanes are free and open to every vehicle, with no tag needed. During toll hours, every vehicle in the lane needs a valid FasTrak toll tag, including carpools that ride free.

The San Mateo operator says you can enter or leave its lanes at any point. Wherever striping shows solid double white lines, California law bars crossing them, so follow the markings. If you miss your chance to merge out, stay in the lane until the next opening.

Who pays what

Your price depends on how many people are in the car and the type of FasTrak tag on your windshield.

One detail catches many drivers. A standard FasTrak tag, the kind without a switch, is always charged the full toll. Only a Flex tag can tell the system you have passengers. If you carpool even occasionally, swap to a Flex tag.

Setting a FasTrak Flex tag

1. Slide the switch to match the number of people in the car: 1, 2 or 3+.
2. Check it every trip. A tag left on 3+ after dropping off passengers can earn a ticket.
3. Motorcycles and two-person two-seaters use 3+.
4. Outside toll hours the setting does not matter.

California Highway Patrol officers watch for solo drivers with tags on 3+. A carpool cheat costs far more in fines than any toll.

How tolls are set

Express lane tolls use dynamic pricing. Overhead signs show the current price to reach the next few exits. Prices rise as the lane fills and fall when traffic is light. The goal, as the San Mateo operator puts it, is to keep the lane moving at 45 mph or more. The price displayed when you enter is the price you pay, even if it rises while you are in the lane.

Neither FasTrak page lists a fixed minimum or maximum toll. The San Mateo operator's FAQ gives sample tolls from $1.50 to $4.50 depending on the number of zones traveled. Peak tolls on a long weekday trip can go well beyond those examples, so read the sign before you commit. Our traffic and rush hour guide explains when the regular lanes jam and the toll is most likely to pay off.

Clean air vehicles

For years, electric and plug-in hybrid cars with California's clean air vehicle decals got carpool lane access and express lane discounts while driving alone. That ended on September 30, 2025, when the federal authority behind the decal program lapsed. The San Mateo operator says the discount ended on that date and has not been extended. From October 1, 2025, a FasTrak CAV tag works like a Flex tag at full rates. Electric car drivers now pay by occupancy like everyone else. If Congress or the state brings the program back, the FasTrak site will say so.

Tolls without a tag

Enter the lane during toll hours without a FasTrak tag and the system photographs your plate. In San Mateo County, a violation notice goes to the registered owner with the toll plus a $10 penalty. A second notice adds a $20 late fee. Unpaid notices can lead to more fees, a DMV registration hold or collections. The operator waives the $10 penalty for first-time violators who open a FasTrak account.

Rental cars

Rental companies each handle tolls differently. Some offer a toll package for a daily fee, some pass through each toll with a service charge and some leave you to pay. Ask at the counter before you drive into an express lane. If you plan to use the lanes often, choose a rental with a clear toll program. You can compare rental cars and their toll options before you book. Our car rental guide covers offices near Palo Alto.

Getting FasTrak

FasTrak is the Bay Area's electronic toll account, run through bayareafastrak.org. One account pays express lanes and the bridge tolls. You can order a Flex tag online and link it to a credit card. The same account also pays the Dumbarton, San Mateo, Bay and Golden Gate bridges, where FasTrak will be the cheapest way to pay from January 1, 2027. Our page on bridges and tolls has those rates.

FasTrak never asks for payment by text message. Scam texts claiming unpaid tolls are common in California. Pay only through the official site or app.

Help for low-income drivers

Express lane revenue in San Mateo County funds the Go Card program. Qualifying county residents can receive a $200 prepaid card for transportation costs such as Clipper value, paratransit or bike rentals. Applicants need an email address and documents showing age, address and income. Cards expire after three years. Details are on the program pages of the 101 Express Lanes site. Palo Alto is in Santa Clara County, so most residents will not qualify, but neighbors in East Palo Alto and Menlo Park may.

Frequently asked questions