Drivers need to be able to see the signs and other traffic control devices far enough in advance to be able to react to the message. How far we cut the brush or grass in front of the sign depends upon the speed of the traffic and the type of sign. Signs can be broken up into two categories, critical and non-critical. Critical signs are Stop, Yield, One Way, Do Not Enter, Wrong Way and other signs that might require the public to stop. All others are non-critical. The following table from the FHWA's Vegetation Control for Safety booklet is a great guide on the minimum distance to trim in advance for sign visibility. You can access and download that entire booklet for additional guidance on sign visibility and other types of sight distance from our Online Resources page.
Table: Clear Distance to see sign.