Unstable Ground Closes 91-5 Ramp

Caltrans officials closed the busy connector between the eastbound Artesia Freeway and southbound Santa Ana Freeway for 12 hours Friday after an eagle-eyed worker noticed the embankment beneath the connector seemed unstable.

“An employee was going by that area and noticed that the shoring appeared unstable and immediately alerted a team of engineers,” said Caltrans spokeswoman Sandy Freedman. She said that the problem was detected early enough and that there was no danger of the ramp collapsing.

The emergency closure began shortly after the problem was spotted about 6:30 a.m. and lasted well into the evening rush hour, making for a tough commute on a stretch of road used by more than 200,000 motorists daily.

The interchange, part of the $1-billion widening of the Santa Ana Freeway, has been under construction for three years. Engineers and construction workers already working at the site turned their attention Friday to stabilizing the compacted dirt underneath the ramp now in use.

A new connector is scheduled to open early next year. It is work on that new ramp, in addition to recent rain, that may have caused the problem that led to Friday’s closure, officials say.

What caused the alarm was the shifting of large pilings that shore up the compacted dirt under the 30-foot high connector ramp. Workers spent the day removing the pilings and then driving them deeper into the earth than before, said Orange County Transportation Authority spokesman Dave Simpson.

The decision to close the connector was called precautionary. To do the work, it may have been necessary to close the lanes regardless of safety concerns, Simpson said.

Word that the closure was likely to last into the evening rush hour went out early in the day to traffic reporters. Electronic freeway message signs suggested detour: taking the Orange Freeway south to the Santa Ana Freeway.

California Highway Patrol officers said the closed ramp didn’t result in terrible delays, most likely because of the advance notice.

Said CHP Officer Mark Reeves, watching a live camera feed from the construction zone at his desk at the Traffic Management Center in Irvine: “It’s rush-hour traffic, kind of heavy. It’s like most rush hours in a construction zone.”

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Fixing the Problem

Construction crews worked Friday to shore up an unstable embankment that forced the emergency closure of the eastbound Riverside Freeway connector to the southbound Santa Ana Freeway.

EB 91 Connector to SB 5:

Shoring shifted, leaving embankment unstable

Shoring removed, driven deeper into ground

Digging, recent rains may have caused slippage

Source: Dave Simpson, Orange County Transportation Authority

Source: OCTA