The Metro Board of Directors on Thursday voted to study ways to improve traffic flow in sluggish carpool and express lanes on Los Angeles freeways, including increasing the number of passengers required for vehicles to use the area’s carpool lanes.

Right now, as solo drivers know all too well, you can use most high-occupancy vehicle lanes in the LA area if your vehicle has a minimum of two occupants. The study will investigate the potential effects of increasing that threshold to three occupants (a driver and two passengers).

The changes could affect lanes considered to be “degraded” by federal standards, which require vehicles in those lanes to average speeds of 45 mph during peak hours over a six-month period. As you might imagine, plenty of vehicles in HOV lanes in and around Los Angeles fail to meet that standard.

Roughly two-thirds of the state’s HOV lanes were degraded between July and December 2015, according to a report that year from the California Department of Transportation.

The report recommended improving speeds in particularly slow-moving lanes by metering certain HOV lanes or even converting them to standard lanes.

The study approved by the Metro board Thursday will also examine possible changes to the complicated express lane system familiar to users of the 10 and 110 freeways. Regulated by FasTrak transponders, these lanes are open to a mix of carpool vehicles, solo drivers, and clean air automobiles.

Potential adjustments to the system could include a new pricing format that fluctuates based on demand and a program for identifying drivers who regularly break the rules regulating use of the lane.

The motion proposing the study also suggested expanding the express lane system and coordinating with Orange County on a region-wide approach to traffic mitigation.