Transcript The Safety Edge :
The Safety Edge
What is it?
How does it work?
What are the benefits?
Mehdi Parvini Sr. Pavement Engineer Safety and Design Team Leader Ph: (916) 498-5853 Ph: (916) 498-5853 Office of Pavement Engineering & Specification Development Caltrans Pavement Management Program Ph:(916) 227-5848
MAKING PAVEMENTS SAFER and MORE DURABLE
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36,700 Fatal Crashes per Year
2006-2008 Average – Source: FARS
530 399 223 3525 344 250 67 971 228 148 489 373 122 98 136 215 3084 385 663 68 447 382 905 577 635 1251 970 1387 1071 782 797 1133 366 857 1421 1074 933 990 1472 776 869 2928 162 383 646 114 563 66 268 124
Average 40,409 Annual Fatalities 3
2008 Fatal Crashes
(Based on FARS)
34,017 U.S. Fatal Crashes 17,818 U.S. Roadway Departures
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59 people will die in a roadway departure crash in the United States today.
1 Fatality Every 24 minutes
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13,242 Roadway Departure Fatalities on Two Lane Undivided
Source: 2008 FARS Data Focused Solution: Low cost Two Lane roadways Roadway Departure 6
Are Drop-offs a Problem?
Vehicle Re-entry 7
Head-on Roll Over Opposite Side Roadside Hazard 8
Was the drop-off the cause?
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Clip of TTI drop off road test:
http://fhwa.na3.acrobat.com/safetyedgedrop
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Location of Drop-offs
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Horizontal Curves
Near Mailboxes Turnouts Shaded Areas 5.
Eroded Areas (Drainage) 6. Asphalt Pavement Overlay 13
Horizontal Curves
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Mail Boxes
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Shaded Areas
Sunlight = Vegetation 16
Asphalt Overlay
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The Safety Edge:
A Practical Solution 18
The Hardware
GDOT Version IV GDOT Version V 19
End Gate Springs
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The Hardware
Trans Tech Shoulder Wedge Maker TM www.transtechsys.com
Advant-Edge TM
Self Adjusting Spring
Key Features
½” Radius Leading Edge 30 0 Forming Edge 45 0 Compound Angle 22
Clip of safety shoe being installed
http://fhwa.na3.acrobat.com/seshoeinstall/
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Line Depicts extension of Pavement Surface
30 o - 35 o
Line depicts a plane parallel to Pavement Surface from the toe of the wedge surface 24
Construction
Clip Shoulders Construct Overlay
Pull Shoulders Flush
No Effect on Production Minimal Monitoring 12.5 mm or 9.5 mm SP 25
Clip of paving without Safety Edge
http://fhwa.na3.acrobat.com/sewoshoe/
Clip of paving with Safety Edge
http://fhwa.na3.acrobat.com/seshoe/
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Breakpoint on wedge Existing pavement edge New graded shoulder Toe of wedge 27
Toe of wedge Location of the existing pavement edge under overlay Breakpoint on wedge 28
Iowa PCCP Safety Edge
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Increased Edge Compaction ?
With Safety Edge Without Safety Edge 30
Edge Compaction
Safety Edge No Safety Edge Six Condition After One Year In-Service 31
Durability
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Benefits of A Safe Edge
Temporary safety benefit during construction Permanent Solution for future drop-off re-emergence Reduce tort liability – Providing “Due Care” Minimal hardware, labor, or material costs Increased Pavement Edge durability 33
Safety Edge Implementation
Standard Practice Projects Built State Evaluating Safety Edge States without activity Pool-fund States
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Every Day Counts (EDC) Initiative
• • • • Initiated Spring of 2010 EDC designed to identify and deploy innovation • • • Shortening Project Delivery Enhancing Safety of our Roadways Improving Environmental Sustainability Safety Edge: 1 of 5 solutions Goal: 40 states adopting Safety Edge by Dec. 2011 35
What can FHWA offer ?
10-12 demo projects for 2010-2011: Free loaner equipment Technical assistance Project documentation Promotional Material Specifications Tech Drawings 36
Safety Edge Detail
Original Width HMA/PCC Lane or Shoulder Existing Lane or Shoulder Variable Width for Safety Edge Aggregate Shoulder or Shoulder Backing Existing Shoulder or Shoulder Backing Safety Edge Angle 30
Factors that Impact the Effectiveness of the Safety Edge
• • • • • • • Edge drop off height Type of highway (undivided, number of lanes) Shoulder width Design speed Curve Rumble strip Ditch/guard rail at the edge
Criteria for Using Safety Edge
For demonstration projects: • All new and rehabilitation pavement projects that create pavement edge drop off more that 0.15 ft For subsequent projects: • Further crash data analysis is underway to come up with most efficient locations for the safety edge
Safety Edge Specification
The contractor shall attach a device to the screed of the paver that confines the material at the end gate and extrudes the asphalt material in such a way that results in a compacted wedge shape pavement edge of approximately 30 degrees (not steeper than 35 degrees). The device shall maintain contact to the road shoulder surface. It shall also allow for automatic transition to cross roads, driveways and obstructions. The device shall constrain the asphalt head reducing the area by 10 to 15% increasing the density of the extruded profile. Conventional single plate strike off are not allowed. The contractor may use the TransTech Shoulder Wedge Maker or the Advant Edge or a similar device that produces the same wedge consolidation results. If the contractor uses a similar device, he must provide proof that his device has been used on previous projects with acceptable results or the contractor shall construct a test section prior to the beginning of work and demonstrate wedge compaction to the satisfaction of the engineer. Short sections of handwork will be allowed when necessary for transitions and turnouts or otherwise authorized by the engineer. This work will be included in the pay item Hot Mix Asphalt.
Safety Edge Cost
• Equipment – about $3,500 (one time expense) • Material – 1% to 2.5% of a typical overlay cost
More Information
http://safety.fhwa.dot.gov/roadway_dept/paveme nt/safedge/ www.pooledfund.org
TPF-5(097) Evaluation of the Safety Edge Specifications and Drawings Safety Impacts of Pavement Edge Drop-offs: www.aaafoundation.org, September 2006 42
Challenge
What will you do this year to make our highways safer ?
Low Cost Focused Proven 43