What is the Proper Length for a Yellow Light?

Drives Should Be Wary of Short Yellow Lights at Camera Enforced Intersections

If you get a red light photo ticket one of the things you should do right away goes back to the location of the intersection listed on the ticket and time the yellow light. Many times cities employ too-short yellow lights which results in more people running red lights (and increased revenue) because they couldn’t stop in time- and you need to make sure this didn’t happen to you.  

Go back to the intersection with a stopwatch and from the time it turns from green to yellow, begins timing until it changes from yellow to red. You’ll want to do this a few times for accuracy. Jot down the yellow time and then make your comparisons.

Are there laws making yellow lights standard? The length of the yellow light cannot be just arbitrary. The California Manual on Uniform Traffic Control Devices (“MUTCD”), prescribes uniform standards for all official traffic control devices in California and the MUTCD section 4D-10 and Table 4D-102(CA), sets forth the minimum time for traffic signal yellow light change intervals. Section 4D-10 also provides that the time for a yellow light change interval may be increased through field review and appropriate judgment of the local agency. The MUTCD is very clear that increasing the yellow light interval above the minimum prescribed in the same section is an option and in no manner a requirement. Decreasing the yellow light interval below the minimum, however, is not an option.

Check the Table (Table 4D-102) to see if the yellow light change interval at your intersection is non- compliant. Here are a couple examples of minimum yellow light times:

• If the posted speed limit is 25 (or less) mph the minimum yellow interval is 3.0 seconds (this includes both right and left-hand turns).
• If the posted speed limit is 35 mph the minimum yellow interval is 3.6 seconds.
• If the posted speed limit is 45 mph the minimum yellow interval is 4.3 seconds.