Minimum Number of Chevrons to Install
Question:
Is there a minimum number of chevrons to install on a 90-degree curve? There is a 72 radius and a recommended warning speed of 15mph (in a 35 mph speed zone)?
Answer:
In general there always needs to be at least 3 chevrons in view to help define the corner.
The MUTCD has a Chevron Spacing (Table 2C-5 in the newest MUTCD, page 158). The values are the same as the old MUTCD and are also listed on page 43 of our Traffic Sign Handbook. While the table lists advisory speed, curve radius, and typical sign spacing in one table, I prefer to think of it as two tables. Use the advisory speed and the radius to figure out the typical spacing and select the one with the lowest value.
| Advisory Speed (mph) | Sign Spacing (ft) |
| ≤ 15 | 40 |
| 20-30 | 80 |
| 35-45 | 120 |
| 50-60 | 160 |
| >60 | 200 |
| Curve Radius (ft) | Sign Spacing (ft) |
| <200 | 40 |
| 200-400 | 80 |
| 401-700 | 120 |
| 701-1,250 | 160 |
| >1,250 | 200 |
Using your values of 72’ radius and a recommended warning speed of 15mph (in a 35 mph speed zone), we get the following spacing.
- 720’ radius à 40’ typical spacing
- Advisory speed of 15 mph à also 40’ typical spacing
We need to see at least 3 chevrons. A good way to check this before installing signs is to put out cones at the 40’ spacing from the beginning of the curve to the end and seeing if there are always 3 cones in view. Adjust and needed and then install the signs.
One final check is that ¼ of a curve at 72’ radius would be 113’. This would be 4 cones around the corner (1 at the beginning of the curve and 3 spaced to the end). Yes, this works out to 120’ total, but we can adjust.