Your dispatcher points out that the designated bypass route around a tunnel that bans placarded vehicles adds 30 minutes to your delivery and tells you to use the tunnel instead. Why is this not a legally valid reason to enter the restricted tunnel?

49 CFR 397.67(b) (lists the valid deviation reasons: no practicable alternative; reasonable deviation to reach a terminal, loading point, or facilities for fuel/food/repairs/rest/safe haven; or emergency conditions); 49 CFR 397.67(c) (operating convenienc

This is the single most common excuse that leads to tunnel-routing citations: 'it's faster' or 'dispatch told me to.' The regulation closes that loophole by name, so a driver who takes the restricted tunnel to save time has no regulatory defense, and the carrier's instruction doesn't transfer the liability away from the driver.