Why do we need to mow grass lined ditches?

Mowing a grass-lined ditch is important for many reasons. Some of the more critical issues are:

Maintain sight distance
Mowing keeps grass and vegetation from interfering with driver’s sight distance, this includes sign visibility.
Keep trees and bushes small
Mowing keeps saplings and small plants from growing up and becoming larger trees and bushes that could be considered fixed objects if struck. Mowing and large vegetation removal should be done in the clear zone of the highway.
Define roadway
Mowing helps drivers get a feel for the road layout and makes sure any fixed objects can be seen. If grass grows too high, drivers may think they can drive into where fixed objects are hidden.
Drainage
Well-maintained slopes and ditches have better drainage characteristics. If the grass is never mowed, ditches and storm systems can become choked with vegetation and lose capacity to handle storm runoff. Once mowed, the cuttings from the overgrown ditch can plug pipes and downstream sections.
Aesthetics
More important than many people think, a good-looking section can reduce driver anxiety and improve safety. This does not mean the grass needs to be kept like a front lawn. A regular program with consistent maintenance practices is all that is needed. Many agencies purposely let the grass grow to several inches to help with erosion without losing any value of aesthetics.

How often a ditch needs to be mowed depends upon the vegetation in the ditch and the issues listed above.

Resources

February 2014