Traffic in the Westside of Los Angeles would be reduced by 24 percent if vehicles were charged a $4 fee during peak hours to travel the freeways and major roadways, according to a study released Thursday by the Southern California Association of Governments.

This is the first study assigning fees to vehicle use that targets a specific region of Los Angeles County since transportation planners and politicians began discussing congestion pricing several years ago as a tool for relieving traffic gridlock and reducing smog and greenhouse gas emissions in Southern California’s traffic hot spots.

A congestion pricing zone

Under the pilot project, vehicle hours on the affected roadways would be cut by one-quarter, while vehicle miles traveled would be reduced by a little more than one-fifth in an area of West Los Angeles and Santa Monica bounded by Montana Avenue and Sunset Boulevard on the north, the 405 Freeway on the east, the 10 Freeway on the south and 20th Street on the west.

All vehicles entering this so-called “Mobility Go Zone” during morning and afternoon rush hours would be assessed a fee, with discounts available for low-income drivers. Trips originating within the zone would not be charged.

The “decongestion fees” are similar to two ExpressLane programs run by the Los Angeles County Metropolitan Transportation Authority, or Metro. In carpool lanes on the 10 Freeway in the west San Gabriel Valley and along the 110 Freeway from south Los Angeles to the South Bay, single-passenger cars are assessed tolls based on congestion rates and distance traveled. Commuters pay for faster rides, while cars in regular lanes generally move slower.

In the pilot study, the concept is taken a step further by charging fees for all lanes of affected roadways within a zone to discourage single passenger drivers from using these freeways during peak congestion times. As a result, driving would drop by 19 percent, according to the Southern California Association of Governments. bus and train rides would rise 9 percent, biking and walking would each increase by 7 percent.

Most congested freeways

The West L.A./Santa Monica area was chosen because it is one of the more traffic-choked regions in Southern California. The 10 and 405 freeways are rated the sixth and third most congested freeways in the nation, respectively, where traffic crawls at 5 mph during peak hours.

Also, it is a major jobs center, attracting commuters to UCLA, St. John’s Hospital, Santa Monica City College, the city of Santa Monica and many other employers from the San Fernando Valley, Central L.A. and the South Bay.

SCAG is encouraging this region, as well as others, to implement congestion pricing. Metro in February began a 24-month study of its own, focused on various heavy-traffic zones in L.A. County.

As a planning agency for the six counties of Southern California, SCAG can only recommend to member cities and counties, said SCAG president Alan Wapner, Ontario city councilman and board member of the San Bernardino County Transportation Authority. Metro, on the other hand, has the power to impose fees.

New concept replaces building freeways

“You can apply it to the San Gabriel Valley, San Fernando Valley and Orange County, basically to any area heavily impacted during certain times of the day,” Wapner said during an interview Thursday.

Metro and SCAG have concluded the Southland can’t accommodate any new freeways. The 5 Freeway widening project in southeast Los Angeles County near the county border may be the last of its kind. Recently, Metro and Caltrans signed off an alternatives to a 710 Freeway extension through South Pasadena and Pasadena which include transit, bike paths and regional roadways — but no freeway or freeway tunnel.

“We recognize we can’t keep building capacity,” Wapner said. “So we are looking at various tools, and tolls are used successfully around the world to improve mobility,” he said.

What about more trains? Wapner said not everyone will take mass transit, especially in spread-out burbs in the Inland Empire, where it is not as convenient to find a train station or bus depot as it is for denser populations in Los Angeles.

A congestion pricing scheme in L.A. County could raise $1.2 billion a year, according to a report from Metro last year. The smaller, pilot program the SCAG study contemplates would generate $69.2 million a year in net revenue.

London, Stockholm, Singapore and Milan recently began charging single-passenger drivers to enter their city central core zones to great success, according to Metro.