Soaring Interchange on Century Freeway to Be One of a Kind

There never has been anything quite like the high-flying, $135-million traffic interchange being built in South-Central Los Angeles to link the new Century Freeway with a remodeled Harbor Freeway.

With the top lanes soaring 120 feet in the air--higher than a 10-story building--the interchange is the biggest, tallest, most costly traffic structure yet built by California Department of Transportation, engineers report.

It is the first time the state’s traffic engineers have integrated three modes of transportation--light-rail trains, high-occupancy vehicles and individual cars--into one giant intersection.

The trains will run along the median strip of the $2-billion Century Freeway, traveling east from the Los Angeles International Airport about 17 miles to Norwalk.

The five-level maze of soaring and curving freeway lanes will feature:

* A railroad station for passengers who want to transfer from the east-west light-rail trains to north-south transitway buses operating along the Harbor Freeway.

* A bus stop two levels below the train station, with stairways, escalators and elevators to link the rail and bus stations.

* A park-and-ride lot off Figueroa Street that is connected by a walkway to a mid-level mezzanine in the interchange. The mezzanine will have bus and train ticket vending machines, route maps and commuter information.

* An interchange within the interchange for High Occupancy Vehicle (HOV) diamond lanes.

The design of the Century-Harbor Interchange breaks with the past. Some engineers are suggesting that it may become as famous as the Four Level Interchange in downtown Los Angeles, which revolutionized freeway interchange design 36 years ago.

“This is a first-ever (design). It will be very interesting to see how it works out,” said Wolfgang Homburger of the UC Institute of Transportation Studies in Berkeley.

The test, he said, will be how willing commuters are to transfer from car to bus to rail transportation at the interchange, with all of its noise and smog.

Eventually there will be nine miles of cloverleaf loops, transition lanes and connecting roads built into the interchange that will be a mile and a half wide and nearly as long. Right now, however, it looks more like a huge puzzle being assembled a piece at a time, an on-ramp here, a crossover there.

When completed, the Century Freeway will cross four north-south freeways, but none of the other new interchanges will be as complex, or quite as costly as the Century-Harbor Interchange, said Caltrans engineer Charles J. O’Connell.

Not only will rail commuters be able to transfer to buses, but buses, vans and car pools will zip along in their own exclusive lanes through “an interchange within an interchange,” he said.

The Harbor Freeway--complete with its own new high-occupancy-vehicle bus and van-pool lanes-- will run through a wide trench at the bottom of the interchange.

The bus stops, mezzanine and train stations will be stacked in the levels above the Harbor Freeway, amid the looping, curving traffic lanes that will angle off in all directions, each of them designed to keep traffic moving at 55 m.p.h., O’Connell said.

Constructed to withstand a 7.0-magnitude earthquake on the Newport-Inglewood Fault, the structure is being built of steel and concrete that is designed to sway, rather than stand rigid against a quake’s shock, O’Connell explained.

“I’m comfortable with design we have. . . . It can withstand the worst quake that’s likely to hit the area,” O’Connell said.

PROFILE OF A ‘SUPER FREEWAY’

The $2-billion Century Freeway will include not only traffic lanes, but also exclusive lanes for van and car pools and a light-rail line. At the Harbor Freeway intersection, the interchange will include parking areas, train stations and bus depots to allow commuters to transfer from cars to trains or buses. Commuters in car- or van-pool lanes will be able to enter and leave the interchange without crossing general traffic lanes.