P25 Specification for High Skid-Resistant Surfacings
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Transcript of P25 Specification for High Skid-Resistant Surfacings
P25 Specification forHigh Skid-Resistant Surfacings
Joanna Towler, NZ Transport AgencyMark Owen, NZ Transport Agency
Simon Fletcher, Fletcher Corporation Ltd3rd International Surface Friction Conference, Safer Road Surfaces – Saving Lives, Gold Coast, Australia,
16 May 2011
Perceptions of High Skid Surfacings
Durable binder and aggregate-based surfacings that provide high skid resistance
That HSRS is not value for money$40 to $60/m2
C.S. $2 - $8/m2; A.C. $11 to $32/m2
There are quality issues HSRS delaminates in a short period of timeSubstrate fails earlyLack of skilled workforce
Whole of Life Costs
In locations where:Natural aggregate polishes within 2 yearsGeometric improvements expensive or impracticalHigh wet-road crash rate
The whole of life costs may show that a HSRS is value for money
Case Study: SH2 Petone Overbridge
SH2 Petone Overbridge
15 – 20 Crashes/yearSpeed environmentIn 1997 calcined bauxite at $50/m2
Post installation: 0.5 Crashes/year
21 year history of injury accidents at SH2 Petone Overbridge
Resurfacing – Open Graded Porous Asphalt (OGPA)
Calcined Bauxite laid 1997
Cost of resurfacing = $40,000Annual crash savings = $1.9 millionFirst year rate of return = 48 (B/C ≈ 400) At the time, the cost of applying calcined bauxite amounted to just two weeks’ crash savings.
P25 Specification
P25 Specification for High Skid-Resistant Surfaces (HSRS)
P25 Summary of Performance Criteria
The HSRS is required to achieve, for the defects liability period:
the specified level of skid resistance (microtexture and macrotexture)the specified levels of material retention and adhesion to the substrate
The substrate shall be strong enough to resist failure planes through the substrate
P25 Performance Criteria
Skid Resistance 0.65 ESC Over 95% of 10 m sections
0.6 ESC Over 100% of 10 m sections
Texture 0.9 mm MPD
P25 Performance Criteria
Binder & Aggregate Retention/Loss
< 0.25 linear m In any 10 m section (both wheelpaths)
< 0.15% In any 10 m section
< 0.1% In any whole site
P25 Performance Criteria
Visual Appearancebinder and aggregate retention/losscrackingjoint cracking
Binder overspill/underspill
Edges, Ridges and joins
P25 Performance Criteria
Loose Aggregate < 150 g/m2 In first 2 months of life
< 50 g/m2 From 2 months to end of Defects Liability Period
Specification Notes
Apply to a completely bone-dry substrateWithin the atmospheric moisture dew point toleranceOn ‘as clean as possible’ substrateApply resin binder to correct minimum thicknessAvoiding laying on multi-layered chip seal (which has poor structural integrity).Strictly following all elements within the manufacturer’s Method Statement
P25 – Next Steps
Currently out for industry sign-offIssue on NZTA website in next 6 weeksNext year we will do P33 Coloured SurfacingE-mail [email protected] if you wish to review the current draftOr visit us at the NZTA stand