A jack-knifed big rig brought traffic on the southbound Interstate 5 to a crawl Saturday morning after the #1, 2, 3 and 4 lanes near Weldon Canyon Road were shut down for a SigAlert. “(The SigAlert) started at 9:43 a.m. and it ended at 11:25 a.m.,” said Officer Peter Nicholson with the Regional Traffic Management Center. “It came out as an injury collision,” he said. Although it was reported as an injury collision, no injuries were serious enough to require transport to a hospital. Traffic was backed up to Magic Mountain Parkway as of 12 p.m. To avoid delays, drivers can exit the freeway at Magic Mountain Parkway and take The Old Road which runs parallel to the freeway. Traffic is traveling at about 10 milers per hour from Magic Mountain Parkway to the Highway 14 interchange.