Advance Placement Distance for Warning Signs
Warning signs are placed in advance of a potential hazard based on the roadway speed limit, the type of response needed (the condition), and the speed associated with the warning sign response. Table 2-1 presents the minimum advance placement distances for warning signs. This table is an expansion of the information in Table 2C-4 from the Texas MUTCD,
including speed limits of 80 and 85 mph, as well as advisory speeds ending in 5 (i.e. 15)
. Table 2-2 provides a description of each condition and information about which warning signs are associated with each condition.Minimum Advance Placement Distance 1 (ft) | |||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Posted Speed or 85th Percentile (mph) | Condition B: Deceleration to the listed advisory speed (mph) for the condition | ||||||||||||||||||
Condition A: Speed reduction and lane changing in heavy traffic 2 | |||||||||||||||||||
B: Stop 3 | 5 4 | 10 4 | 15 4 | 20 4 | 25 4 | 30 4 | 35 4 | 40 4 | 45 4 | 50 4 | 55 4 | 60 4 | 65 4 | 70 4 | 75 4 | 80 4 | |||
20 | 225 | 100 6 | NA 5 | NA 5 | NA 5 | — | — | — | — | — | — | — | — | — | — | — | — | — | |
25 | 325 | 100 6 | NA 5 | NA 5 | NA 5 | NA 5 | — | — | — | — | — | — | — | — | — | — | — | — | |
30 | 460 | 100 6 | NA 5 | NA 5 | NA 5 | NA 5 | NA 5 | — | — | — | — | — | — | — | — | — | — | — | |
35 | 565 | 100 6 | NA 5 | NA 5 | NA 5 | NA 5 | NA 5 | NA 5 | — | — | — | — | — | — | — | — | — | — | |
40 | 670 | 125 | 100 6 | 100 6 | 100 6 | 100 6 | NA 5 | NA 5 | NA 5 | — | — | — | — | — | — | — | — | — | |
45 | 775 | 175 | 125 | 125 | 125 | 100 6 | 100 6 | 100 6 | NA 5 | NA 5 | — | — | — | — | — | — | — | — | |
50 | 885 | 250 | 200 | 200 | 200 | 175 | 150 | 125 | 100 6 | 100 6 | NA 5 | — | — | — | — | — | — | — | |
55 | 990 | 325 | 275 | 275 | 275 | 225 | 225 | 200 | 150 | 125 | 100 6 | NA 5 | — | — | — | — | — | — | |
60 | 1,100 | 400 | 350 | 350 | 350 | 325 | 300 | 275 | 225 | 200 | 150 | 100 6 | 100 6 | — | — | — | — | — | |
65 | 1,200 | 475 | 450 | 450 | 425 | 400 | 400 | 350 | 325 | 275 | 225 | 200 | 125 | 100 6 | — | — | — | — | |
70 | 1,250 | 550 | 525 | 525 | 525 | 500 | 475 | 450 | 425 | 375 | 325 | 275 | 225 | 150 | 100 6 | — | — | — | |
75 | 1,350 | 650 | 625 | 625 | 625 | 600 | 575 | 550 | 500 | 475 | 425 | 375 | 325 | 250 | 200 | 100 6 | — | — | |
80 | 1,475 | 750 | 750 | 725 | 725 | 700 | 675 | 650 | 600 | 575 | 525 | 475 | 425 | 350 | 300 | 225 | 150 | — | |
85 | 1,575 | 850 | 850 | 850 | 825 | 800 | 775 | 750 | 725 | 675 | 625 | 575 | 525 | 475 | 400 | 325 | 250 | 150 | |
1 The distances are adjusted for a sign legibility distance of 180 feet for Condition A. The distances for Condition B have been adjusted for a sign legibility distance of 250 feet, which is appropriate for an alignment warning symbol sign. For Conditions A and B, warning signs with less than 6-inch legend or more than four words, a minimum of 100 feet should be added to the advance placement distance to provide adequate legibility of the warning sign.2 Typical conditions are locations where the road user must use extra time to adjust speed and change lanes in heavy traffic because of a complex driving situation. Typical signs are Merge and Right Lane Ends. The distances are determined by providing the driver a PRT of 14.0 to 14.5 seconds for vehicle maneuvers (2004 AASHTO Policy, Exhibit 3-3, Decision Site Distance, Avoidance Maneuver E) minus the legibility distance of 180 feet for the appropriate sign.3 Typical condition is the warning of a potential stop situation. Typical signs are Stop Ahead, Yield Ahead, Signal Ahead, and Intersection Warning signs. The distances are based on the 2004 AASHTO Policy, Exhibit 3-1, Stopping Site Distance, providing a PRT of 2.5 seconds, a deceleration rate of 11.2 feet/second2 minus the sign legibility distance of 250 feet.4 Typical conditions are locations where the road user must decrease speed to maneuver through the warned condition. Typical signs are Turn, Curve, Reverse Turn, or Reverse Curve. The distance is determined by providing a 2.5 second PRT, a vehicle deceleration rate of 10 feet/second2 minus the sign legibility distance of 250 feet.5 No suggested distances are provided for these speeds, as the placement locations are dependent on site conditions and other signing. An alignment warning sign may be placed anywhere from the point of curvature up to 100 feet in advance of the curve. However, the alignment warning sign should be installed in advance of the curve and at least 100 feet from any other signs.6 The minimum advance placement distance is listed as 100 feet to provide adequate spacing between signs. | |||||||||||||||||||