Interstate 15 through Blackfoot reopened early Saturday morning, ending a more than 24-hour closure that brought the freeway to a near standstill and contributed to a second major crash between two semis.

Miraculously, neither semi driver was injured in Friday’s wreck, but authorities are urging extreme caution as the reopened interstate has been reduced to one lane in each direction on the northbound side. The southbound lanes both remain completely closed.

Idaho Transportation Department officials said they plan to reopen both northbound lanes and one southbound lane this week as repairs continue on the Riverton Road overpass, which was severely damaged when a tanker truck slammed into it Thursday night.

Despite the extensive damage, ITD officials believe the overpass can be repaired rather than replaced, though the timeline remains unclear.

The chaos began around 8:47 p.m. Thursday when a 46-year-old Jerome man driving a 2026 Kenworth towing an empty milk tanker veered off the freeway’s southbound lanes and slammed into a pillar supporting the Riverton Road overpass, according to Idaho State Police.

The driver suffered serious injuries in the violent impact and was airlifted via emergency helicopter from the scene to Eastern Idaho Regional Medical Center in Idaho Falls. Authorities have not released his name or provided an update on his condition.

The collision nearly severed a concrete bridge pillar, compromising the overpass’s structural integrity and forcing authorities to immediately shut down both the bridge and freeway below. Photos from ITD revealed the devastating damage — a pillar shattered down to its rebar barely keeping the overpass from collapsing.

ITD crews worked non-stop to stabilize the structure, stacking concrete blocks, wood and steel beams to shore up the damaged overpass. Their round-the-clock efforts paid off when Interstate 15 reopened around 1:30 a.m. Saturday, ahead of schedule.

The reopening ended the freeway detour through Blackfoot that had choked the city with traffic Friday.

“We have been working around the clock to restore the flow of traffic,” ITD District Engineer Todd Hubbard said. “Early (this) week, we hope to have traffic restored to proper lanes. Southbound I-15 will be reduced to one lane until a permanent fix can be made.”

The current single-lane configuration means slower speeds and long delays for motorists traveling the region’s busiest thoroughfare.

State police are still investigating what caused the tanker truck to veer off the freeway.

The lengthy closure created a cascade effect Friday afternoon when the massive traffic backup reportedly contributed to a collision between two semis on northbound Interstate 15 between Fort Hall and Blackfoot.

A 2012 Freightliner driven by a 45-year-old Rexburg man was slowing in the heavy congestion around 1:30 p.m. when a 2020 Freightliner driven by a 28-year-old man from Saskatchewan, Canada, struck it from behind, state police said.

The impact sent the 2020 Freightliner into the median, where it overturned.

Neither driver was injured, but the collision compounded the gridlock for hours.

While the left northbound lane of Interstate 15 was blocked for only 20 minutes, the southbound left lane remained shut down for more than five hours — just miles from where Thursday night’s crash had closed the freeway entirely.

With much work still needed to repair the damaged overpass, it’s anyone’s guess as to when Interstate 15 will be brought back to full capacity.

But credit ITD for being able to reopen the freeway so soon after a devastating crash brought it to a halt.