vegetation control for safety russ johnson – maintenance supervisor - wsdot don petersen –...
TRANSCRIPT
Vegetation Control For Safety
Russ Johnson – Maintenance Supervisor - WSDOT
Don Petersen – Safety/Design Engineer - FHWA
Overview
Introduction Specific Items to Check
Sign Visibility Clear Sight Lines Drainage Side Road Visibility Roadside Trees Pedestrian Paths
Overview (continued)
Keeping Traffic Control Devices Visible Stopping Sight Distance on Curves Intersection Sight Distance Mowing for Safety Resources on Vegetation Control for
Safety
Introduction
1. Scope and Objectives 2. Goals of Vegetation control3. Roadside Vegetation Management
Scope and Objectives
1. Safety is a main concern2. One potential hazard is vegetation3. The purpose of this presentation
Vegetation Control Goals
1. Keeping Signs visible to drivers2. Keeping road users visible to drivers
1. Other vehicles2. Bicycles3. Pedestrians
3. Improving visibility of livestock and wildlife4. Improving pedestrians and bicyclists see vehicles5. Keeping sidewalks and paths clear and free
Vegetation Control Goals
6. Removing trees close to roadway7. Helping drainage systems function8. Preserving pavements9. Controlling noxious weeds
Roadside Vegetation Management
Specific Items to Check
Sign visibility1. Visible to drivers at all times2. Look for braches and brush that
block signs and other control devices
3. Signs that control right-of-way are most critical (stop and yield signs)
Specific Items to Check
Clear Sight Lines1. Tall grass and brush in the shoulder,
ditch and backslope can obscure:1. Culvert Headwalls2. Drainage inlets3. Guardrail end4. Object markers5. Livestock and wildlife
Drainage
Weeds, turf and sod can interfere with drainage:
1. Creates a secondary ditch2. Pavement problems3. Ponding on pavements causing
hydroplaning or areas prone to icing
Side Road Visibility
Roadway intersections increase the potential for crashes
1. Mainline drivers need to see entering vehicles2. Entering drivers need to see mainline vehicles
Roadside Trees
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
Pedestrian Paths
Increased emphasis on walking for exercise and transportation
Importance of pedestrian safety and accessibility Free of overhanging or protruding
vegetation Tripping hazards caused by sidwalk
displacement
Sidewalk Corridor Zones
Furniture Zone
Pedestrian Zone
Frontage Zone
Keeping Traffic Control Devices Visible
Unobstructed line of sight to roadside signs or hazards
Far enough ahead to allow safe reaction time
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
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
Intersection Sight Distance
A clear line of sight along crossroad
Early enough to see1. Conflicting vehicles2. Bicyclists3. Pedestrians
Mowing for Safety
Three types of mowing1. Safety mowing2. Transition Mowing3. Selective mowing
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 Associationwww.nrvma.org
