Vegetation Control For Safety

1. Vegetation Control For Safety Russ Johnson – Maintenance Supervisor - WSDOT Don Petersen – Safety/Design Engineer - FHWA

2. Overview • Introduction • Specific Items to Check • Sign Visibility • Clear Sight Lines • Drainage • Side Road Visibility • Roadside Trees • Pedestrian Paths

3. Overview (continued) • Keeping Traffic Control Devices Visible • Stopping Sight Distance on Curves • Intersection Sight Distance • Mowing for Safety • Resources on Vegetation Control for Safety

4. Introduction • Scope and Objectives • Goals of Vegetation control • Roadside Vegetation Management

5. Scope and Objectives • Safety is a main concern • One potential hazard is vegetation • The purpose of this presentation

6. Vegetation Control Goals • Keeping Signs visible to drivers • Keeping road users visible to drivers • Other vehicles • Bicycles • Pedestrians • Improving visibility of livestock and wildlife • Improving pedestrians and bicyclists see vehicles • Keeping sidewalks and paths clear and free

7. Vegetation Control Goals • Removing trees close to roadway • Helping drainage systems function • Preserving pavements • Controlling noxious weeds

8. Roadside Vegetation Management

10. Specific Items to Check • Sign visibility • Visible to drivers at all times • Look for braches and brush that block signs and other control devices • Signs that control right-of-way are most critical (stop and yield signs)

16. Specific Items to Check • Clear Sight Lines • Tall grass and brush in the shoulder, ditch and backslope can obscure: • Culvert Headwalls • Drainage inlets • Guardrail end • Object markers • Livestock and wildlife

21. Drainage • Weeds, turf and sod can interfere with drainage: • Creates a secondary ditch • Pavement problems • Ponding on pavements causing hydroplaning or areas prone to icing

23. Side Road Visibility • Roadway intersections increase the potential for crashes • Mainline drivers need to see entering vehicles • Entering drivers need to see mainline vehicles

28. RoadsideTrees • One of the most common cause of fatal and serious injury crashes • Clearzone • Adjacent to roadway • Clear of fixed objects • Trees larger than 4 inches • The closer to the roadway

33. Pedestrian Paths • Increasedemphasis on walking forexercise and transportation • Importance of pedestrian safety and accessibility • Free of overhanging or protruding vegetation • Tripping hazards caused by sidwalk displacement

35. Sidewalk Corridor Zones Furniture Zone Pedestrian Zone Frontage Zone

37. Keeping Traffic Control Devices Visible • Unobstructed line of sight to roadside signs or hazards • Far enough ahead to allow safe reaction time

38. Stopping Sight Distance (SSD) on Curves • Vegetation on the inside of curves restrict the drivers line of sight • Cut weeds, brush, or trees for adequate stopping sight distance • Sight distance is the distance necessary to notice a problem, realize a stop is necessary, and to come to a complete stop

39. SSD on Curves • SSD is important on all roads • Sight distance is measured along the travel path of the vehicle • The following slide illustrates how to determine SSD

42. Intersection Sight Distance • A clear line of sight along crossroad • Early enough to see • Conflicting vehicles • Bicyclists • Pedestrians

47. Mowing for Safety • Three types of mowing • Safety mowing • Transition Mowing • Selective mowing

49. Resources • A Policy on Geometric Design of Highways and Streets, 2004 • “Integrated Roadside Vegetation Management”, NCHRP Synthesis 341 • Manual on Uniform Traffic Control Devices, 2003 • Volume 3: A Guide for Addressing Collisions with Trees in Hazardous Locations, NCHRP Report 500 • FHWA Roadside Vegetation Management http://www.fhwa.dot.gov/environment/index.htm • National Roadside Vegetation Management Association www.nrvma.org

50. Questions? JOHNSRA@wsdot.wa.gov- 509-324-6589 Don.Petersen@fhwa.dot.gov - (360)534-9323