Chief among those factors is the Drug and Alcohol Clearinghouse. Since January 2020 when the Federal Motor Carrier Safety Administration began recording substance abuse violations in the clearinghouse database, over 91,000 drivers have been taken off the road for testing positive or refusing to take a test. That number is expected to hit 100,000 before the end of the year.

While this is considered proof that the clearinghouse is doing its job — keeping unsafe drivers off the road — it is also increasing pressure on carriers trying to deal with unprecedented freight demand.

"We've lost, at least temporarily, 44,000 drivers so far in 2021 to drug or alcohol violations, which really stings when freight is sitting at the dock waiting to be picked up," P. Sean Garney, the Scopelitis Transportation Consulting co-director, told FreightWaves. 

"With only 21% of drivers disqualified from driving a [commercial motor vehicle] taking the steps necessary to get back behind the wheel, the industry needs to continue to find creative ways to fill seats."