An 18-wheeler jackknifed on September 18, 2026, completely shutting down the southbound lanes of Interstate 35 near Loop 1604 in the San Antonio area. According to the Von Ormy Police Department, the crash happened shortly before 10:00 a.m.
Police said the 18-wheeler was carrying a load of car parts when it jackknifed across the highway. Von Ormy Police traffic safety officers and Bexar County Fire responded to the scene. All southbound traffic was forced onto the frontage road while crews worked to clear the truck.
No injuries were reported. The crash caused significant congestion along I-35, with traffic backing up as motorists were diverted from the main lanes. Storms were beginning to move into the San Antonio area around the time of the crash, although officials had not determined what caused the truck to jackknife.
Jackknife crashes can block an entire highway within seconds
A jackknife accident occurs when the tractor and trailer rotate toward one another rather than remaining aligned. Once the trailer begins swinging sideways, a driver may have very little ability to regain control before the truck occupies several lanes.
On a heavily traveled interstate such as I-35, the danger extends well beyond the truck itself. Vehicles approaching from behind may suddenly encounter a trailer extending across the roadway. Drivers may brake aggressively, leave their lanes, strike another vehicle, or collide directly with the tractor-trailer.
The absence of reported injuries in this incident is fortunate. A similar 18-wheeler accident during heavier traffic or at higher speeds can cause a chain of serious collisions.
Investigators should determine why the trailer began to swing
A truck does not jackknife without some loss of stability between the tractor and trailer. The investigation should determine what happened immediately before the truck rotated across the highway.
Hard braking can contribute to a jackknife if the tractor or trailer wheels lose traction. A sudden steering maneuver may produce a similar result. Investigators may also examine whether the truck encountered standing water, reduced pavement friction, another vehicle, a tire problem, or a mechanical failure.
The weather conditions deserve review because storms were moving into the area. Rain can reduce traction and increase stopping distances. If water accumulated on the roadway, a tractor-trailer may become more difficult to control during braking or lane changes.
There has been no official finding that weather caused this crash. Roadway and weather conditions should instead be considered alongside the physical and electronic evidence from the truck.
Wet pavement can increase the risk of losing control
Commercial drivers must adjust their operation when roadway conditions deteriorate. A tractor-trailer traveling safely on dry pavement may require substantially more distance to slow or stop once rain begins.
An 18-wheeler can hydroplane when its tires lose sufficient contact with a wet roadway. Even a partial loss of traction can make braking and steering more difficult.
Drivers also need to consider visibility, spray from surrounding vehicles, traffic congestion, and the possibility of standing water. A sudden braking maneuver on a wet interstate can produce a very different result than the same maneuver on dry pavement.
Investigators may compare the timing of the storm with the crash, inspect the road surface, review weather data, and determine whether other motorists reported slick conditions.
Cargo can influence trailer stability
Police said the 18-wheeler was loaded with car parts. The investigation should identify what was being transported, how much the load weighed, how it was distributed, and how the cargo was secured.
Shifting cargo can change the balance of a trailer during braking or steering. If heavy automotive components move suddenly inside a trailer, the weight transfer can make an already unstable truck more difficult to control.
Investigators may review bills of lading, loading diagrams, cargo photographs, securement equipment, weight records, and information identifying who loaded the trailer. If cargo contributed to the crash, responsibility may extend beyond the driver.
An overloaded 18-wheeler can also have different braking and handling characteristics. There is no current indication that this truck exceeded applicable weight limits, but the load should still be documented during the investigation.
Brakes and tires should be inspected after a jackknife crash
Braking systems are especially important in jackknife investigations. A brake failure or imbalance between tractor and trailer brakes may affect how the combination responds during a sudden stop.
Tires also play a major role in maintaining traction. Worn tread, improper inflation, damaged tires, or a tire blowout can make a large truck harder to control.
The tractor and trailer should be inspected before damaged components are repaired or replaced. Brake condition, tire tread, inflation, suspension, coupling equipment, and other systems may provide evidence about why the truck became unstable.
A proper pre-trip inspection is intended to identify obvious safety defects before a commercial truck begins its route.
I-35 carries significant commercial truck traffic through San Antonio
The risks of 18-wheeler accidents in San Antonio are particularly apparent along major corridors such as I-35, where local commuters share the roadway with commercial traffic traveling through Central and South Texas.
Interstate conditions can change rapidly. Heavy traffic may require abrupt slowing. Entrance and exit ramps create frequent merging. Construction and congestion can limit available escape routes. Weather can further reduce the amount of time drivers have to respond safely.
When an 18-wheeler jackknifes across an interstate, motorists behind the truck may have nowhere to go. This makes maintaining appropriate speed, following distance, and vehicle control especially important.
Driver fatigue and operating history may also be reviewed
There is no indication that fatigue played a role in this crash. Commercial truck investigations nevertheless commonly include a review of the driver’s work and rest history.
Driver fatigue may impair judgment and reaction time. A fatigued driver may recognize slowing traffic later, brake more abruptly, or respond poorly to changing weather and roadway conditions.
Investigators may review driver logs, electronic logging information, dispatch records, fuel receipts, route information, and communications with the trucking company.
Those records can establish how long the driver had been working and whether required rest periods were observed.
Electronic data can show what happened before the truck jackknifed
One of the most important sources of information may be the truck itself. Commercial vehicles can contain black box data recording speed, braking, throttle position, engine operation, and other information surrounding a crash.
That data may show whether the driver braked suddenly, whether speed changed before the jackknife, and how the truck responded as control was lost.
Other evidence may include tire marks, roadway gouges, photographs, cargo records, truck inspection documents, maintenance records, dash camera footage, and witness statements.
Nearby traffic cameras and other surveillance footage may show when the trailer began rotating and whether another vehicle contributed to the emergency maneuver.
The official accident report may later provide additional information about the truck, driver, roadway conditions, and contributing factors identified by investigators.
Trucking company practices may become relevant
A jackknife crash investigation should extend beyond the driver’s actions when the evidence supports a broader review. Trucking company liability may arise from poor maintenance, inadequate driver training, unsafe scheduling, improper loading practices, or pressure placed on a driver to operate despite dangerous conditions.
The motor carrier’s records may show who inspected the truck, when it was last serviced, whether defects had previously been reported, and how the company monitored its drivers.
If another company loaded the automotive parts, investigators may also need to determine whether that company properly distributed and secured the cargo before the truck entered I-35.
Speak With an 18-Wheeler Accident Lawyer After a Jackknife Crash
Spagnoletti Law Firm represents people and families affected by serious trucking accidents, cargo-related incidents, and other commercial vehicle collisions. When an 18-wheeler jackknifes across a highway, the investigation should determine whether braking, speed, weather, tire condition, cargo movement, maintenance problems, driver conduct, or trucking company practices contributed to the loss of control.
An 18-wheeler accident lawyer can help preserve evidence, obtain black box data, review the accident report, secure video footage, evaluate cargo and trucking company records, and determine who may be legally responsible.
We offer a free consultation, and we handle trucking accident cases on a contingency fee basis, meaning there are no upfront attorney’s fees and we are paid only if we recover compensation for you.
If you or a loved one has been impacted by an 18-wheeler accident, call Spagnoletti Law Firm at 713-804-9306 or contact us online.