Road Side Design: When is a Barrier Required?

Road Side Design: When is a Barrier Required? Jennifer Schmidt, Ph.D., P.E. University of Nebraska-Lincoln Department of Civil Engineering Guide Rail Safety Symposium Brampton, ON October 24, 2017

Research organization located at University of Nebraska-Lincoln Teaching students with research Started in the late 1980 s Clients State DOTs FHWA Private industry Department of State Motorsports organizations Manitoba Infrastructure and Transportation

Research Capabilities Develop, test, evaluate roadside & motorsports safety hardware & features Component and full-scale vehicle crash tests high-speed, large-mass, high-energy impacts ISO 17025 certified laboratory FHWA & European impact safety standards DOS security barrier standards Non-linear finite element analysis Materials characterization & testing Implementation guidelines

MwRSF Facilities Materials & Simulation Laboratory Vehicle & Fabrication Shop Outdoor Proving Grounds

We are doing good in motorsports Prior to the SAFER Barrier, an average of 1.5 fatalities per year Since the installation of SAFER Barrier, there have been no fatalities due to impacts with the outer wall

SAFER Barrier IRL-20 135.6 mph, 26.4 deg. IRL-24 133.1 mph, 26.9 deg. Up to 76% reduction in forces on the occupant

How about on the roadsides? Vehicle accident fatalities in 2015 35,092 in US 1,858 in Canada Estimated cost have reached well over $50 billion annually tc.gc.ca iihs.org

Vehicle Fatalities in U.S. iihs.org

Vehicle Casualties in Canada tc.gc.ca

Casualties in Canada tc.gc.ca

Vehicle Crashes Approximately 56% of crashes are Roadway Departure crashes in US Roadway Departure Vehicle leaves traveled way Crosses center line or edge line

safety.fhwa.dot.gov Roadway Departure Crashes

Keep Vehicles on the Roadway Pavement Friction Rumble Strips Horizontal Curve Safety Nighttime Visibility safety.fhwa.dot.gov

Provide for A Safe Recovery SafetyEdge Clear Zones safety.fhwa.dot.gov

Reduce Crash Severity Ideally no vehicles would leave the roadway or would be sufficient clear zones completely free of hazards Vehicles continue to leave roadway Prevent vehicles from interacting with and impacting hazards

Hazards are Everywhere

Types of Roadside Hazards Trees Utility Poles Steep Slopes Signs Drainage Features Lakes, Rivers, Oceans, Etc. Bridges Barriers Everything in a City

Just Remove All the Hazards! You can drive safely on or off the road

What to do with all the hazards? AASHTO Roadside Design Guide, hazards on the roadside should be: Removed Redesigned to be safer Relocated Make it breakaway (and safer) Shield it Delineate it

Sometimes that means Cutting down a tree that gets hit frequently Grading roadsides to make more traversable slopes Designing and evaluating roadside safety hardware to shield hazards

How to Decide If a Hazard Needs Treatment If the safety benefits from a specific safety design or treatment equal or exceed the additional costs for that treatment Benefit/Cost (B/C) Analysis Example Program: RSAP (Roadside Safety Analysis Program)

Benefit/Cost Analysis The estimated benefits to be derived from a specific course of action are compared to the costs of implementing that action Cost with barrier: installation cost, maintenance cost, crash cost (may be more frequent but lower severity) Cost without barrier: crash cost (typically higher severity) AASHTO RDG

Benefit/Cost Analysis Factors: Design speed Traffic volume Evaluate options: Remove or reduce the area of concern so no shielding would be required Install an appropriate barrier Leave the area of concern unshielded AASHTO RDG

Roadside Trees tentree.com

Trees - Background Naturally occurring roadside fixed objects 8% all traffic-related fatal crashes (FARS 1999-2009) 90% tree impact fatalities located on 2- lane roadways (FARS 1999-2009) 30% fatalities occur on low-volume roads (FARS 1999-2009) 26% fixed-object fatal crashes (FARS 2009)

AASHTO RDG Tree Treatment

Tree Treatments Pavement marking Rumble strips Signs Delineators Roadway improvements Tree removal Shielding AASHTO RDG

Low Volume Roads Simulated Do nothing baseline Tree removal Install longitudinal barrier Other Options Delineation Edge treatments

Install Longitudinal Barrier High installation costs $18.16/lf plus terminal $45/lf plus terminal Viable situations Very long sections of close spaced trees Difficult tree removal Regular new tree growth Scenarios evaluated not cost effective

Tree Removal, B/C = 4 ADT 0-99 100-199 200-299 300-399 400-500 No. of Trees 1 2-10 11-25 >25 Tree Diameter, Spacing, and Offset Dependent Remove Tree(s)

Example: Georgia DOT

Killer Trees Urban Non-Collision Fatal Tree Fall Great Falls, VA in 2012

AASHTO RDG Utility Pole Treatment

AASHTO RDG Breakaway Luminaire Poles

Breakaway Signs

Breakaway Sign Supports

Overhead Sign Structures May need a barrier if located in clear zone

Offset From Hazard Based on dynamic deflection from barrier testing Varies for different barriers AASHTO RDG

Foreslope Configurations Recoverable: 1V:4H or flatter Non-recoverable: 1V:3H to 1V:4H Critical: steeper than 1V:3H AASHTO RDG

Midwest Guardrail System - M30 Guide Rail

AASHTO RDG Note Not all barriers are meant to be placed on the slope or at the slope break point

AASHTO RDG

Drainage Features

Culvert Grate

Bridge Rails

Test Level MASH Barrier Test Levels Test Vehicle Vehicle Weight (kg) Speed (km/h) Angle (degrees) 1 1100C Small Car 2270P Pickup Truck 1,100 2,270 50 50 25 25 2 1100C Small Car 2270P Pickup Truck 1,100 2,270 70 70 25 25 3 1100C Small Car 2270P Pickup Truck 1,100 2,270 100 100 25 25 4 1100C Small Car 2270P Pickup Truck 10000S Single-Unit Truck 1,100 2,270 10,000 100 100 90 25 25 15 5 1100C Small Car 2270P Pickup Truck 36000V Tractor-Van Trailer 1,100 2,270 36,000 100 100 80 25 25 15 6 1100C Small Car 2270P Pickup Truck 36000T Tractor-Tank Trailer 1,100 2,270 36,000 100 100 80 25 25 15

Barrier Selection Test Level All test levels developed to contain passenger cars and pickup trucks Select test level based on roadway speed and ADT Higher performance levels (TL-4, TL-5, TL-6) may be selected: High percent average daily truck traffic Adverse geometrics Severe consequences of penetration into opposing lanes AASHTO RDG

Barrier Selection Low volume, low commercial vehicle Cable or box beams system High volume with large number of trucks Steel beam or concrete barrier High volume with very large number of trucks in critical areas High performance barrier RSM

Bridge Rails & Concrete Barriers End of bridge rail or concrete barrier can be hazardous if not shielded appropriately

Sloping the end not so good

Transition Adjacent to Rigid Barrier

Transition to Rigid Barrier

Summary Installing barriers is not always the best solution when hazards are near roadway Barrier itself is a hazard (but a safer one) A few fatalities occur with barrier impacts Appropriate barriers do save lives Limited funds exist for installing barriers Need to prioritize locations Accident history Benefit/cost analysis

QUESTIONS? Jennifer Schmidt (402)-472-0870 jennifer.schmidt@unl.edu mwrsf.unl.edu