The Metropolitan Transportation Authority in Los Angeles is considering ending the free use of toll roads by zero-emission vehicles because of concerns about congestion.

The Los Angeles Times says the idea is being discussed in order for it to hit its target of a minimum freeway speed of 45 miles per hour at rush hour and that at present zero-emission cars with one occupant “are no different from a gas guzzler” when it comes to “taming traffic jams”.

The report notes that tolls on the Harbor Freeway and the San Bernardino Freeway fluctuate between 35 cents to $2 per mile during rush hour, based on how many drivers are in the paid lanes. In theory, a higher toll discourages some drivers from using the lanes, freeing up space and speeds for those who remain. But drivers of zero-emission vehicles are immune to the price hike so continue to use the lanes whatever the conditions.

However the LA Times comments that the proposal could place Metro on a collision course with environmental advocates, who say saving time and money on Los Angeles County’s toll lanes is a major reason that Angelenos buy zero-emission cars and that reducing emissions from transportation is critical to meeting the state’s air quality and climate goals.