Dear Street Smart: After the Big Medium...

Dear Street Smart: After the Big Medium One, I’ve noticed that the freeway overpasses in the San Fernando and Santa Clarita valleys--where the freeway goes over something--are higher than the rest of the freeway, causing a sudden rise when you reach the overpass and a drop thereafter.

My question is simple: Did the overpass rise up in the earthquake? Or did the rest of the freeway settle down? (A chicken and egg problem?) And regardless of what did what, my second question: Why?

Michael Kotch

Castaic

Dear Reader:

You are a very perceptive driver. There is indeed a slight rise in the pavement when you reach certain bridges near the epicenter of January’s Northridge earthquake.

In answer to your first question, the bridges stayed right where they were, but the rest of the freeway settled half an inch or so during the shaking, according to Caltrans spokesman Joe Shaw.

Here’s how it happened: Freeway roadbeds are built on top of a layer of highly compacted dirt that is 10 to 12 feet deep. During the initial 6.8 jolt and the subsequent aftershocks, the less-compacted dirt underneath the layer put down by the California Department of Transportation settled slightly--causing the roadbed to drop with it.

Because bridges are built on separate foundations, they stayed put.

Shaw said crews will be working over the next few weeks and months to smooth out the height difference so it is less noticeable to drivers. That will be done either by putting another layer of pavement down or by injecting pressurized mud underneath.

In the meantime, there is no structural danger.

Dear Street Smart:

Why would we spend millions of dollars on the Metrolink rail system that only runs in one direction in the morning and afternoon? Is this state of the art?

Mark Taraborelli

Glendale

Dear Reader:

The answer to your question is pretty simple: Metrolink follows existing commuting patterns. Consider that the Golden State Freeway heading into Downtown is a lot more crowded every morning than it is heading out. In other words, more people want to get to Downtown than to, say, Santa Clarita.

Understandably, Metrolink officials want to provide the most bang for your buck. Trains heading into the hinterlands would not have enough riders to make financial sense, according to Metrolink spokesman Peter Hidalgo.

At least not yet.

Remember that the Metrolink system is slightly more than a year old. In that time, it has expanded into all five Southern California counties. Now, Hidalgo said, plans are in the works to run more trains along its existing lines--including weekend trains, evening trains and even trains that run opposite to traditional commuting patterns.

It all comes down to time and money.

“No new system can be everything to everyone right when it’s open,” Hidalgo said. “But we gradually want to phase in more and better and faster and safer service. You will not see Metrolink operating only during rush hours for very much longer.”

Dear Street Smart:

The two traffic lights on Hollywood Way at the north end of Burbank Airport still stop traffic on this busy street 24 hours a day, even though the Lockheed parking lot (which is served by one of the lights) is almost empty. The few cars there now could well wait for gaps in traffic and do not need traffic lights.

What do you think?

Stuart Campbell

Glendale

Dear Reader:

We took your question to Mike Moss, senior civil engineer for the city of Burbank, who told us that the two signals are scheduled to stay in operation as long as the parking lot is in use.

“Until Lockheed completely leaves that area, we’re almost locked in,” Moss says. “There’s a number of people who are still parking at that parking lot.”

But take heart: Word is that the parking lot may be discontinued by the end of the year. And until then, the signal does employ a “loop-detection” system that switches the light to red for traffic on Hollywood Way only when a car is waiting to exit the lot. Otherwise, “it should stay on green,” Moss says.

Street Smart appears Mondays in The Times Valley Edition.