Configurations of rumble strips vary based on many interrelated factors. This diagram offers a series of configuration recommendations by source:
Swarco Industries, Inc.: Recommend sets of 6 strips each, spaced 1 ft. apart for speeds of 30-40 mph, 2 ft. apart for speeds of 40-55 mph, and 3 ft. apart for speeds of 55 mph or greater.
FHWA Best practice G4-10: Thermoplastic rumble strips are...4 inches wide, .25 in. thick with the following spacing: 2 sections – 10 transverse strips, 6 feet apart, then 90 feet away the next section starts with 10 transverse strips, 4.5 feet apart.
Plastic Safety Systems: Recommend 3 or more strips per array, with 3 ft. between strips for speeds of 35 mph or less, and 4 ft. between strips for speeds greater than 35 mph.
NCHRP Report 476: Sets of six parallel strips spaced about 10 ft. apart are acceptable for high-speed roadways, with closer spacing for slower speeds. Widths of 4-6 in. and heights of approximately 0.5 in. have been widely used and normally provide adequate warning without being too severe or endangering motorcycles.
Ennis-Flint: Rumble bar spacing is variable due to the roadway situation being addressed and vehicle speed. It is effective to have more than one field of bars...Recommend 10 strips spaced 6 ft. at 55mph and 1 strip spaced 4 ft. 6 in. at 35 mph.
Advanced Traffic Markings: Rumble strips should be applied in three sets of ten. The strips in set one should be 10 ft. apart followed by 500 ft.; in set two the strips should be 5 ft. apart followed by 500 ft.; in set three the strips should be 1.5 ft. apart.
NYSDOT Special Report 140: Rumble Strips of 10 mm thickness ± 3 mm should be in sets of six strips spaced at no more than 2.7 m apart and preferably at irregular intervals with the spacing determined by the speed limit. A spacing of 1.8 m to 2.4 m between strips should be used when the speed limit is below 50 mph and 2.1 m to 2.7 m spacing when the speed limit is 50 mph or greater.