The National Transportation Safety Board has released a preliminary report regarding the road treatment strategies used to address the freezing conditions that caused the February crash in Fort Worth that involved more than 133 vehicles.
At least six people died and dozens more were injured in a massive pileup on the North Texas Express toll lanes on Feb. 11 that occurred after overnight sleet made for treacherous driving conditions.
All southbound lanes of Interstate 35W north of downtown, including the interior toll lanes where the crashes took place, remained closed through the day and overnight as firefighters and other first responders worked in bitterly cold temperatures to clear the damaged vehicles from the highway.
Dubbed a "mass casualty incident" by firefighters, officials said during a news conference that at least 65 people received treatment at area hospitals, including 36 who were transported from the scene by ambulance.
According to the National Transportation Safety Board, in the days leading up to the crash, the area had experienced 36 consecutive hours of below-freezing temperatures.
In anticipation of forecast freezing rain and sleet, NTE Mobility Partners Segments 3 reported that they had pretreated the traffic lanes with an Ice Slicer NM brine solution.
The solution was applied to the two southbound toll lanes in the vicinity of the crash on February 9 at 10:12 a.m., the National Transportation Safety Board said.
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According to the National Transportation Safety Board, about four hours before the crash, the weather station at Fort Worth Meacham International Airport, about three miles northwest of the crash site, reported light freezing rain and freezing mist.
At 3:40 a.m., the dynamic message signs managed by NTEMP S3 along the southbound toll lanes began displaying the message, "ICY CONDITIONS EXIST / PLEASE USE CAUTION," the National Transportation Safety Board said.
The message was based on information from an earlier crash that occurred 3:08 a.m. when icy road conditions existed at I-35W and Western Center Boulevard, about five miles north of the crash site.
The National Transportation Safety Board said the wreck happened at about 6 a.m. in the southbound toll lanes, which had a speed limit of 75 miles per hour. Concrete barriers separated the southbound toll lanes from the northbound toll lanes and from the southbound general-use lanes.
The crash involved both commercial and passenger vehicles and covered a segment of roadway approximately 1,100 feet long. As a result of the crash, six people were fatally injured, the National Transportation Safety Board said.
The National Transportation Safety Board said two of the fatally injured people were pedestrians who exited their vehicles and were struck on the road, while the other fatally injured people had remained inside their vehicles.
According to the National Transportation Safety Board, 36 vehicle occupants were transported to area hospitals for treatment of their injuries.
NTEMP S3 was responsible for operations and maintenance in the I-35W right-of-way, which included toll lanes, general-use lanes, and frontage roads.
NTEMP S3, the Texas Department of Transportation, the Fort Worth Police Department, the Fort Worth Fire Department, and the Metropolitan Area EMS Authority are supporting the National Transportation Safety Board in the investigation.
The National Transportation Safety Board said information in this report will supplemented or corrected during the course of the investigation.