The backup ZipMobile will be called into service for the Thursday morning commute after the machine that broke down in March malfunctioned again Wednesday while removing barriers it uses to create the extra lane on the H-1 freeway for rush hour.

The ZipMobile had an electrical fire in its engine Wednesday afternoon, leaving 1 mile of the ZipperLane still open in westbound lanes of the freeway between the Nimitz Highway onramp near Sand Island Access Road and the H-1 airport offramp.

A tow truck was used to pull the vehicle to close the remaining barrier segments, and the lane was removed in time for normal afternoon traffic.

The ZipperLane is created during the morning rush hour to help ease Honolulu-bound traffic on the freeway. The barriers used to create it are usually removed by the ZipMobile for pau hana traffic.

When the ZipMobile broke down on March 31, it triggered 36 hours of westbound gridlock.

Four westbound lanes were closed to afternoon traffic after a faulty power pack that runs the machine’s retractable arm caused a computer failure and the ZipMobile stalled in the Waikele area while removing the extra carpool lane.

DOT officials knowingly violated DOT protocol to have at least one ZipMobile operable and removed the good power pack from the backup ZipMobile.

Once inside the primary ZipMobile, however, the replacement power pack also failed — and a massive traffic jam resulted.

A technician from California had to travel to Hawaii to repair it.

This time, the main engine that runs the ZipMobile itself suffered an electrical malfunction, said Tim Sakahara, Department of Transportation spokesman.

"Fortunately, the engine that powers the arm is still OK," Sakahara said. "This time it’s the engine that moves the vehicle forward and backwards."