The Hard Line : Caltrans Is Adding Concrete Barriers to I-5 Oleanders for Safety

The oleander shrubs that grace the freeway medians have been a signature of Southern California’s landscape for 20 years. While adding a touch of beauty to the motorist’s drive, the pink- and white-blossomed foliage also conceals safety barriers that help prevent errant cars from crossing into oncoming traffic.

The California Department of Transportation recently embarked on a project to construct concrete walls along the median of North County’s section of Interstate 5, while keeping the oleander intact. Studies show the concrete to be a safer alternative to the cable barriers now in place, officials say.

Several lawsuits throughout the state allege that some freeways are unsafe because they lack a concrete barrier separating opposing lanes of traffic.

The stretch of freeway being retrofitted extends from Via de la Valle in Del Mar to Tamarack Avenue in Carlsbad. Caltrans said it has no plans to build barriers on Interstate 15.

What barriers are currently in place?

Secreted inside the oleander bushes planted on the medians of I-5 are cables strung between metal posts. These cables stand about 2 feet high and were intended to stop cars from crashing through the foliage and into oncoming traffic.

Studies conducted by Caltrans, however, showed that the effectiveness of the cables was dicey. They stretched on impact, and smaller cars could easily slip underneath the slack lines. And, the cables didn’t always restrain heavier cars and trucks.

Officer John Marinez of the California Highway Patrol said the cables do slow people down, but he has also seen accidents in which they were not effective.

“I have investigated accidents where cars have gone right underneath the cable and some have gone right over the top of the cables and ended up on the opposite side of the freeway,” Marinez said. “It is not common, but it does happen.”

What will the new barriers be like?

Caltrans explored numerous safety measures, including metal walls, poles and water barriers. Planners decided to replace the cables with concrete barriers.

The barriers, which will stand about 3 feet tall, will have a flared base--a design that will force a wayward car to run parallel with the barrier rather than hit it head-on, Caltrans spokesman Tom Nipper said.

“You don’t want to redirect a car back out into traffic or cause a direct impact,” he said. “By design, the wall is made to lessen that impact and keep cars from going into a head-on collision with cars doing freeway speeds in the other direction. A cable barrier couldn’t provide that.”

What will become of the oleander landscaping?

The oleander will stay. Caltrans is constructing the barriers on both sides of the existing foliage. Because oleander grows up to 12 feet tall, motorists will still have a close-up view of the pink blooms.

Drought-tolerant and fast-growing, oleander thrives on the abuses of freeway life, including direct sunlight and poor air quality, and officials say it is being kept for its low maintenance as much as for its aesthetic value. But not as a buffer against traffic hazards, Caltrans says.

“We never plan landscaping as a safety concern,” Nipper said. “We don’t plant a tree to stop a car. The concrete barrier has proven to be the safest barrier in use.”

What are the state’s safety guidelines for barriers?

The state doesn’t require a barrier for medians wider than 45 feet, but the median on I-5 in North County is considerably less, Nipper said.

There is a 10- to 12-foot shoulder between the cable barriers and the traffic lanes, he said, and that will not change with the concrete walls.

Unlike the oleander-cable medians, concrete barriers can give the illusion of a narrower roadway, but the sensation depends on how close a motorist is to the barrier and how small the car is, Nipper said. Most cars are 7- to 8-feet wide, which leaves ample space between car and barrier, he said.

“If you have a small car, you are pretty much looking straight across at that barrier and it looks a lot bigger, gives the illusion it will swallow your car,” Nipper said. “You have the same width of lane, but you can get a tunnel vision of sorts.”

How much will the barriers cost? Where is the money coming from?

The cost of the 13-mile project from Del Mar to Oceanside is $2.7 million, Nipper said. It is funded by the State Highway Safety Project, which receives some of its money from gasoline taxes.

When will the project be done?

Construction began Sept. 21 and will continue through February.