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NASA Engineer Says CBBT Wind Restriction Scale Needs An Update


Following the recent death of a trucker whose rig plunged off of the Chesapeake Bay Bridge Tunnel, a former NASA engineer says that the wind restriction scale requires adjustment to accommodate the size and shape of modern trucks.

CBBT Wind Restriction Scale Is Over 50 Years Old

Rick Wood, who was formerly in charge of NASA’s wind tunnels and now works in truck aerodynamics, says that his calculations indicate that the CBBT wind restrictions scale is in need of an update.

After the death of 47 year old trucker Joseph Chen raised questions about the safety of the CBBT for truckers, Wood began running calculations on the 52 year old wind restriction system.

Investigators ruled Chen’s crash off of the CBBT a result of driver error, but Wood’s calculations suggest that the current wind restriction system may not be sufficient to ensure truck driver safety.

He found that semi trucks on the CBBT are the safest when the force of gravity is three times the force of the wind (you can read more about Wood’s calculations and safety assessment here).

Wind Restriction Scale Due For An Update

Given this ratio, he  found that the current wind restriction scale is not sufficient to guarantee safety.

Wood specifically says that the current distinction between the Level 1 (40 to 46 m.p.h. winds) and Level 2 restrictions need reworking: “So if the wind is blowing at 46 mph, you’re allowed to cross with no weight. But at 47, you need 30,000 pounds? From an engineering standpoint, that makes no sense. At Level 1, you should have to carry at least 15,000 pounds.

He also found that several other factors like the lift force created by forward motion, lighter modern trailers, and aerodynamic devices like wind skirts and wheel covers could also contribute to a CBBT blow over.

Wood said, “I’m not saying they did anything wrong. I’m just saying they need to update their system.

The Virginia Pilot Online


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