When determining pattern length for barricades, which formula is described?

When determining pattern length for barricades, which formula is described?

• A. Pattern length equals the speed limit plus the work area.
• B. Pattern length equals the speed limit times the work area.
• C. Pattern length equals 10 times the speed limit plus the work area.
• D. Pattern length equals the speed limit minus the work area.

Answer: (C)

Pattern length is a practical rule that ties traffic speed and the work area into a repeating distance. The standard approach multiplies the posted speed limit by ten to estimate the distance drivers need to perceive, react, and begin to decelerate within a work zone, and then adds the length of the work area itself so there’s enough room to protect workers and equipment. Put together, this gives a repeating pattern that provides adequate visibility and buffer for motorists as they approach and pass through the zone. For example, at 55 mph the speed component is about 550 ft, and adding the work area length (say 300 ft) yields a pattern length of roughly 850 ft. This is why the ten-times speed plus the work area formula is used. Other formulas would under- or over-estimate the needed distance and could compromise safety.

Pattern length is a practical rule that ties traffic speed and the work area into a repeating distance. The standard approach multiplies the posted speed limit by ten to estimate the distance drivers need to perceive, react, and begin to decelerate within a work zone, and then adds the length of the work area itself so there’s enough room to protect workers and equipment. Put together, this gives a repeating pattern that provides adequate visibility and buffer for motorists as they approach and pass through the zone. For example, at 55 mph the speed component is about 550 ft, and adding the work area length (say 300 ft) yields a pattern length of roughly 850 ft. This is why the ten-times speed plus the work area formula is used. Other formulas would under- or over-estimate the needed distance and could compromise safety.