Vegetation Control for Driver Visibility

Why It’s a Core Responsibility of Every Highway Department

Maintaining safe and passable roadways involves more than fixing potholes or plowing snow. One often-overlooked but critically important task for municipal highway departments is mowing and controlling roadside vegetation to preserve driver visibility.

When grass, brush, or tree limbs encroach upon the road, they can block sightlines at intersections, obscure traffic signs, and even conceal hazards like pedestrians or wildlife. Proper vegetation management is not just good housekeeping - it directly impacts roadway safety and helps municipalities meet their duty of care to the traveling public.

The Safety Case for Vegetation Control

Visibility is vital for driver safety. Overgrown vegetation can lead to:

• Obstructed stop or yield signs, increasing crash risk at intersections.

• Blocked views of oncoming traffic at hills and curves.

• Hidden roadside hazards, such as culverts, ditches, or parked vehicles.

• Reduced reaction time due to limited sight distance.

These risks are especially pronounced on rural roads, where vegetation growth is rapid and shoulders may be narrow.

Key Areas to Prioritize

Municipal highway departments should target vegetation control in areas that most directly impact visibility and safety:

• Approaches to intersections and driveways.

• Inside and outside curves.

• Sight triangles (the clear area drivers need to see approaching traffic).

• Around traffic signs, guardrails, and traffic signals.

• Road shoulders, to maintain clear pavement edges.

A well-planned mowing and trimming program addresses these areas first, even if full roadside mowing must be staged over time.

Mowing Practices

Most towns and highway departments adopt seasonal mowing cycles:

• Spring/early summer mowing targets initial growth and ensures clear sightlines during the busy travel season.

• Mid-summer mowing manages peak growth and prepares for late-summer traffic.

• Late fall mowing reduces brush encroachment ahead of winter.

Departments often mow a standard width off the pavement, wider on high-speed roads, narrower on low-volume streets.

Brush and Tree Maintenance

Mowing alone isn’t enough. Brush and tree trimming are key to long-term visibility:

• Mechanical cutting removes dense roadside brush.

• Manual tree trimming addresses overhanging limbs and low-visibility zones.

• Selective herbicide use (where legal and appropriate) helps manage regrowth.

Brush control also protects infrastructure by keeping drainage systems and guardrails clear.

Why Recordkeeping Matters

Municipal liability is an important consideration. If an accident occurs and poor visibility is cited as a factor, municipalities must be able to demonstrate that they have an active and reasonable vegetation management program in place.

That’s why it’s critical to:

• Document mowing dates and locations.

• Log tree and brush maintenance work.

• Keep records of visibility inspections and public complaints.

Many highway departments now use simple asset management software to streamline this documentation process, which is an approach strongly encouraged by liability insurance carriers.

A Shared Responsibility

Ultimately, keeping sightlines clear is a shared responsibility between highway departments, public works staff, and municipal leaders. Budgeting sufficient resources for vegetation control is a wise investment in public safety.

By treating mowing and vegetation control as core safety tasks, not just routine maintenance, municipalities can help ensure that their roads remain as safe and navigable as possible.