3 rd International Road Surface Friction Conference SAFER ROAD SURFACES – SAVING LIVES May 2011 Queensland

Innovative Surfacing Treatments Delivering Safer Roads Gerard Killick Spray and Blending Divisional Manager Jeff Waters Surfacing Development Engineer Dr Bryan Pidwerbesky General Manager – Technical

Outline  Background – why did Fulton Hogan develop these new technologies?  MultiSpray® variable transverse bitumen application  Ultra high pressure watercutter  PAVEtex  thin, textured gap graded asphalt mixes  Conclusions

Why did Fulton Hogan develop these new technologies?  Changes to road asset management since 1995  All road construction & maintenance activities in New Zealand had to be outsourced  Emphasis on providing appropriate level of skid resistance to reduce accidents  Constrained road maintenance budgets  Encouraged innovation by industry

One Problem  Texture variation is a major difficulty

Another Common Problem

Micro- vs Macro-texture

Old Solutions to Texture Variation  Strip sealing, or  Two passes of sprayer of differing application, one for shoulders and centreline, another for the wheelpaths  Two sprayers are used on extreme sites  Objective: “uniform” texture across the pavement from which to start again

Voids in Seal Coats Binder Bitumen Chip Unfilled voids Average Least Dimension (ALD)

Needed New Solutions  In 1996 Fulton Hogan started a major upgrade of its chip sealing capability –Sprayers and Chip Spreaders.  Next generation of chip sealing: –Variable application of binder & chip –Automated texture measurement –Computerised data output/control

Applications  Preventative: Reseals on high trafficked chip seals. Optimum binder in wheelpaths  Corrective: One pass spraying on seals with flushed wheelpaths &/or coarse shoulders  Optimised : Spray run widths sites where traffic islands / pedestrian islands require variable spray width

Extending Seal Life on Low Volume Roads Using Variable Distribution  Reducing risk of: –Flushing in wheeltracks –Stripping between & outside wheelpath  Field Trials since 1999  Verified design algorithm for MultiSpray variable application rate

Field Application captured on carpet strips

Transverse Variable Binder Application Rates

Variable transverse application of binder Less binder is sprayed in wheel tracks, with no chip loss: At least 10% less for unflushed sites At least 20% less for flushed sites Reduces the use of non-renewable resource (bitumen) Extends the texture depth life of chip seals

Conclusions & benefits  By applying correct amount of bitumen from first reseal, varied across the width of the lane, flushing is prevented  Improved safety when sealing  Easier for traffic control & to work around fixtures such as poles & curbs  Improved quality  Improved productivity

Ultra High Pressure Watercutting

Background  Developed in NZ in early 2000  Environmentally friendly  Much safer than hot / solvent alternatives WatercutUncut Bitumen burning being performed prior to the development of the watercutter

Cuts away unwanted excess bitumen, restoring texture and vastly improving hysteresis and adhesion friction. Water energy dissipated on contact with seal aggregate and doesn’t dislodge chip. Effect on Chipseal Surface BeforeAfter

Re-texturing Asphalt Removes a very small amount of fines as well as excess binder from the surface to expose the aggregate. This increases surface texture.

Early Trials View north from uncut section Feb 06 Christchurch, South Island Cut Section Uncut Section

Land Transport New Zealand Research Project: Investigating the Lifecycle of Water Cutter Rejuvenation of Aggregates

 How long does the improvement last?  Sustainability  Recycling the surface Reasons for the Project

Site Descriptions  Sites were deficient in friction but not texture (surface stones were polished, but no bleeding)  Varied climate  Varied Aggregate: Greywacke, Schist, basalt, sandstone, gneiss  Varied Surfacing types: single coat, two coat, AC, Open Graded Porous Asphalt  Various geometry and traffic levels.

Conclusions  Watercutting improved microtexture & macrotexture of polished surfaces  Microtexture improvement can last > 5 years  Watercutting does not sharpen up rounded edges on worn surfaces  Watercutting is a cost effective resurfacing treatment but is not a cure all for flushing, bleeding and polishing problems  Sections identified as deficient by skid resistance survey can be made safe until resurfacing

PAVEtex UTA 12mm

What is PAVEtex UTA?

Cost-effective  Laid 15mm thick is significantly lower cost than mix laid 25-30mm thick.  Thicker binder film thickness ensures more durable so longer life than OGPA or AC10mm mix on flexible pavements.  Lasts longer than chip seals in high stress situations.  Doesn’t waste high value high PSV aggregate by burying them in the body of the mix.

Environmentally Friendly  Reduced use of non- renewable resource compared with other TA surfacings.  Reduced use of non- renewable resource when compared with multiple short lived seals.  Lower noise than chipseal and asphaltic concrete

Variety of Applications  Bridge decks  High stress bends  Wet, damp, shaded areas  Rural intersections  Industrial areas  Motorways

Conclusions PAVEtex UTA:  Is a cost effective solution based on life cycle costing.  Provides adequate texture depth that provides good skid resistance  Is not suitable for sites with significant flushing or extreme stress  Is not waterproof when laid 15-20mm thick - a membrane seal or heavy tack coat underneath would minimise water ingress.

Innovative Surfacing Treatments Deliver Safer Roads