SAN DIEGO (CBS 8) - For years California highway officials have been encouraging drivers to use the carpool lanes, but now it appears the state's HOV and express lanes are being overused, leaving Caltrans to come up with a solution.

Take a drive during rush hour on Interstate 5, and you'll see what all the fuss is about. Drivers are used to seeing gridlock in the regular lanes, but now more and more vehicles are slowing down in the HOV lanes as well.

"If the freeway is totally cogged, the carpool lane is going to be the same," a driver said.

Carpool lane gridlock is a problem up and down the state, especially in Orange County and Los Angeles. In fact, some HOV lanes are so slow, they don't meet federal speed standards. To fix the problem, some cities are requiring a minimum of three passengers in the HOV lane, instead of just two, with mixed reactions from drivers.

"Very reasonable solution. They do that in the Bay Area. Seems like a good number," a driver said.

"I don't know, for families like us, it's great we can use the carpool lane with just the two of us," another driver said.

Thankfully, carpool lane traffic jams are less common in San Diego County, limited mainly to Intestate 5 through Del Mar and Solana Beach.

Caltrans is working on a solution to the I5 bottleneck. The plan is to extend the existing HOV lanes north.

"At the end of this year, motorists will see construction of two HOV lanes extending from the end now in Solana Beach up towards 78," Caltrans spokesperson Edward Cartagena said.

Four years ago, the state stopped allowing yellow-stickered hybrid vehicles into the carpool lanes with solo drivers. Currently you can still drive solo in the HOV lane with an electric car, but if the gridlock continues, that perk could go away as well.

"As far as kicking the electric cars out, I don't think that's a good idea because, I mean, those are good for our environment," a driver said.

Solo drivers using fast track also clog up the express lanes, but so far there are no plans to eliminate that source of transportation income.

"It's a benefit for people who have a Fast Pass because we can use it, and it's a benefit for the state because we pay a lot. Sometimes I pay $8 to use it," a driver said.

If California doesn't find a way to fix its carpool lane gridlock, it risks losing federal highway funding. Caltrans says that is not likely to happen anytime soon because the agency has various action plans in place to keep traffic moving statewide.

Some of the footage used in this video report was shot using a GoPro camera.