Underride accidents happen when a smaller vehicle slides beneath the rear or side of a large truck, such as an 18-wheeler. These crashes often result in catastrophic damage because the smaller vehicle’s upper structure may be sheared off on impact.
Several factors contribute to the occurrence of underride collisions, many of which are preventable.
Insufficient truck visibility
One of the most common causes of underride accidents is poor visibility. When a truck lacks reflective markings, functioning lights, or proper hazard signals, it becomes difficult for other drivers to detect it—especially in low-light or inclement weather. Drivers approaching a dimly lit or poorly marked trailer may not have sufficient time to react.
Weak or missing underride guards
Federal law requires many trailers to have underride guards, which are metal bars designed to prevent smaller vehicles from sliding underneath during a rear-end collision. However, not all trailers comply, and some guards are poorly maintained or structurally inadequate. If a guard fails upon impact, it defeats its intended purpose.
Excessive speed and tailgating
Speeding or following a truck too closely significantly raises the risk of an underride crash. Trucks require longer distances to stop due to their weight and size. When a car follows too closely, any sudden stop can lead to a collision. Even momentary distractions can eliminate a driver’s ability to respond in time.
Unsafe merging or lane changes
Trucks have substantial blind spots, especially along the sides and rear. If a truck driver merges without properly checking these zones, a smaller vehicle can get trapped underneath. Similarly, when drivers underestimate the length or turning radius of a truck, dangerous side-impact underride accidents can occur.
To avoid underride accidents, maintain a safe following distance, avoid lingering in a truck’s blind spots, and stay especially cautious in low-visibility situations. Defensive driving around commercial trucks can significantly lower your risk.