COLUMBIA--A state program to stop killer cross-median interstate highway wrecks with cable barriers is entering its final construction phase.

Beginning next month, the state Transportation Department opens bidding for 70.4 miles of cable barrier construction that will cost about $4.2 million and separate highways where medians are no wider than 72 feet, agency spokesman Pete Poore said Wednesday.

The state has 834 interstate highway miles.

The first phase of the program began in December 2000 along 213 miles with medians no wider than 36 feet. The second phase covered 113 miles with medians up to 60 feet wide.

Winning contractors also are responsible for fixing damaged barriers within four days of an accident.

The repairs cost an average of $974, Poore said. Since the first barriers were installed in December 2000 through June 2003, vehicles hit the cables 2,953 times -- an average of seven times a day -- prompting about $2.9 million worth of repairs.

The Transportation Department bills those responsible for damaging the barriers. So far, 630 people have been billed for $859,000. The state has recouped $654,000 of that.

The cable barrier program began following years of deadly cross-median accidents. "There wasn't any knee-jerk reaction to any crash situation," Poore said.

One of the worst came three years ago on July 24, 2000. Eight people died on Interstate 26 near Chapin when a delivery truck blew a tire and veered across the median into a sport utility vehicle packed with people headed for vacation.

A stretch of Interstate 77 in Columbia with narrow medians that was the site of three fatal cross-median crashes in 1997 was the first to get the barriers.