The company responsible for operating and maintaining I-35W in Fort Worth failed to effectively monitor and address icy roadway conditions during the 2021 winter storm, which contributed to a 130-car pileup, according to a National Transportation Safety Board report.

According to the report, the crashes occurred Feb. 11, 2021, on an elevated section of the southbound toll lanes of I-35W. It involved commercial and passenger vehicles. As a result of the crash, six people died, and 36 others were transported to area hospitals.

The crash sequence began at 6:04 a.m., according to the NTSB, when several vehicles in the southbound toll lanes slid on the elevated roadway and crashed into concrete barriers beside the toll lanes. As approaching drivers encountered the vehicles involved in these initial crashes, they were unable to stop on the icy roadway, leading to secondary crashes. As a result of the crash event, six people were fatally injured. Four of the fatally injured people remained inside their vehicles; two were struck on the roadway after they had exited their vehicles.

The Dallas-Fort Worth area experienced 36 consecutive hours of below-freezing temperatures in the days leading up to the crash.

According to the report, North Tarrant Express Mobility Partners Segment 3, the company responsible for the operations and maintenance on the I-35W right of way, had pretreated the two southbound lanes with a liquid brine solution 44 hours before the crash. On Feb. 11, company employees spot-treated some sections of roadway with salt, but they did not treat the elevated portion of I-35W where the multivehicle crash occurred.

According to the report, maintenance crews drove north on I-35W approximately 45 minutes before the crash and visually checked the road. They detected no moisture and so did not apply salt. NTSB investigators found that NTEMP S3’s roadway monitoring process was deficient because as precipitation and freezing temperatures continued and conditions deteriorated on the morning of Feb. 11, company personnel did not identify the elevated portion of I-35W as needing additional deicing treatment, which left the roadway surface icy.

NTSB investigators also found drivers traveling at speeds too fast for winter weather conditions contributed to the severity of the crash. The roadway has a 75-mph speed limit.

As a result of the investigation, the report stated the NTSB is making the following recommendations:
  • Implement a statewide plan to install environmental sensor stations in priority locations to enable timely response to hazardous road conditions during inclement weather.
  • Provide a comprehensive winter weather training program to private and state-regulated toll facilities so they can train their employees using the program.
  • Enact legislation to allow the Texas Department of Transportation to install variable speed limit signs on Texas roadways.​​
The report also stated the NTSB reiterated five previous recommendations, including automated speed enforcement and increased connected vehicle technology deployment.

In addition to being responsible for operations and maintenance on the I-35W right of way, NTEMP S3 manages and operates several expressways in North Texas, including North Tarrant Express Texpress, NTW 35W Texpress and LBJ Texpress.