Thousands of North San Diego County drivers noticed the carpool lanes down Interstate 15 are changing once a week.
Two giant trucks called Barrier Transfer Machines (BTM) usually sit on the North or South end of the carpool lanes the rest of the week.
“You never see it. It’s Thursdays. Thursdays only,” said David Cox, who regularly uses the carpool lanes during his commute from Escondido.
Thursday is the only day the BTMs make the two-hour trek to move the concrete barriers dividing the highway. The machines give three carpool lanes to the rush hour direction and one in the opposite direction.
“Seems like it needs to be moved other days,” said Cox.
“This actually helps on Thursdays,” said CalTrans spokesman Edward Cartagena. “Thursday, statistically, is our heaviest travel day of the week.”
Cartagena said CalTrans has studied I-15 traffic for years. He said one stretch of the highway sees 296,000 vehicles every day.
However, the carpool lanes aren’t always full. Cartagena said Thursday is the only day they need the BTMs to get to work. Each one costs roughly $1 million. The BTMs could be put into service more if more people start using the carpool lanes.
“Every time we get data in, it’s a learning curve for us,” he said.
“Not sure I buy that because I see plenty of congestion on other days,” said Cox.
Cartagena added more BTMs are expected to be used when Interstates 5 and 805 are expanded in San Diego County.