MUTCD advance warning sign spacing calculator
Sign placement distances A, B and C by road type, per MUTCD 11th Edition Table 6B-1.
Drives the advance warning sign spacing. The urban low/high speed split is set by the highway agency, not by the MUTCD.
Posted speed limit, off-peak 85th-percentile speed prior to work starting, or anticipated operating speed.
First sign (A)
100ft
MUTCD 11th Ed, Table 6B-1
Second sign (B)
100ft
Distance from first sign
Third sign (C)
100ft
Distance from second sign
Distance upstream of the transition
Total advance warning area 300 ftW20-7 — FLAGGER (symbol)
36" × 36" minimum
100 ft
W20-4 — ONE LANE ROAD AHEAD
36" × 36" minimum
200 ft
W20-1 — ROAD WORK AHEAD
36" × 36" minimum
300 ft
All road types
MUTCD 11th Ed, Table 6B-1Urban (low speed)
City street, typically 40 mph or less
100 / 100 / 100 ft
Urban (high speed)
Urban arterial, typically above 40 mph
350 / 350 / 350 ft
Rural
Open rural highway
500 / 500 / 500 ft
Expressway / Freeway
Limited access facility
1000 / 1500 / 2640 ft
Related distances
MUTCD 11th Ed, Table 6B-2Longitudinal buffer space
Stopping sight distance at 35 mph
250 ft
Reading Table 6B-1
The advance warning area is measured backwards from the transition. The A dimension puts the first sign — the one a driver reaches last, closest to the work — at its distance from the taper. B and C then step further upstream to the second and third signs.
On a rural highway with a three-sign series, that puts the nearest sign 500 feet from the taper, the second at 1,000 feet, and the third at 1,500 feet, for a 1,500-foot advance warning area. MUTCD Section 6B.05 notes that rural conditions normally warrant an advance warning area of 1,500 feet or more.
Urban street placement
Section 6B.05 paragraph 04 gives a rule of thumb for urban streets: the effective placement of the nearest warning sign, in feet, should range from 4 to 8 times the speed limit in mph, with the high end used when speeds are relatively high. Rural highways run longer, from 8 to 12 times the speed limit in mph.
Frequently asked questions
- How far apart do work zone advance warning signs go?
- MUTCD 11th Edition Table 6B-1 gives 100 feet for urban low-speed streets, 350 feet for urban high-speed streets, 500 feet for rural highways, and 1,000 / 1,500 / 2,640 feet for expressways and freeways.
- What do the A, B and C dimensions mean?
- A is the distance from the transition or point of restriction to the first sign. B is the distance between the first and second signs. C is the distance between the second and third signs. The first sign is the one closest to the TTC zone; the third is furthest upstream.
- Where is the urban low-speed / high-speed threshold?
- The MUTCD does not set one. Table 6B-1 footnote states the speed category is to be determined by the highway agency or owner of the site roadway. Most agencies split at 40 mph, which is what Conemap defaults to, but check your agency.
- Are these distances mandatory?
- No. MUTCD Section 6B.05 paragraph 07 states the Table 6B-1 distances are approximate, intended for guidance purposes only, and should be applied with engineering judgment, adjusted for field conditions where necessary.
- How short can the advance warning area be?
- When a single advance warning sign is used, such as on a low-speed residential street, the advance warning area may be as short as 100 feet, per MUTCD Section 6B.05 paragraph 05.