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Research Report 347 Characterising pavement surface damage caused by tyre scuffing forces

Published: | Category: Activity management , Research programme , Research & reports | Audience: General

The transverse shear forces generated by multi-axle groups depends on many factors including turn geometry, vehicle type, axle weights, tyre size and configuration, suspension geometry, and the number and type of axles. This study quantifies the impact of some of these parameters on the transverse pavement shear forces or scuffing forces generated during constant low-speed turns. A field trial on an unbound granular pavement structure with chipseal surfacing assessed the level of scuffing force that caused visible wear on the pavement surface. A computer model of a tandem simple-trailer was used to simulate the forces observed in the field. Computer models were used to assess the effects of axle load, axle group spread, wheelbase, and turn geometry on peak scuffing forces; to simulate various low-speed turns; and to identify the relative impact of the peak scuffing forces for the different vehicles.

Research Report 598 Cracking in specialist surfacing systems

Published: | Category: Activity management , Research programme , Research & reports | Audience: General

Specialist surfacings such as high-friction and coloured traffic-calming surfaces have gained huge popularity since their introduction. However, the reputation of these specialist systems in New Zealand is also plagued by premature failures due to cracking and other related modes.

Research Report 278 Factors affecting multiple chipseal layer instability

Published: | Category: Activity management , Research programme , Research & reports | Audience: General

The accumulation of chipseal layers following repeated road resurfacing frequently results in an unstable surface that can flush quickly, sometimes within twelve months. Many pavements in New Zealand that have multiple chipseal layers have not developed instability problems, and the reasons why some multiple layers develop the problem and others do not was the focus of this investigation, carried out between August 2002 and August 2004. Keywords: chipseal, instability, multiple chipseals, pavement, roads, seal layer, shear

Research Report 334 Flexural modulus of typical New Zealand structural asphalt mixes

Published: | Category: Activity management , Research programme , Research & reports | Audience: General

Structural hot mix asphalt (HMA) pavements have become popular in New Zealand in recent times as heavy traffic volumes have increased and early failures of granular pavements have become more common, especially in urban areas where road maintenance causes major traffic disruption.

Research Report 252 New standard precast concrete bridge beams: stage 1 – identification of new standard beam shapes

Published: | Category: Activity management , Research programme , Research & reports | Audience: General

The objective of Stage 1 of this research project (carried out in 2002-2003) was to research and identify the most appropriate precast concrete bridge beam shapes that should be adopted in New Zealand as industry standards for the future. This research was considered a priority as the standard bridge beam designs currently used in New Zealand had been adopted as industry standards in the 1970s. These designs are therefore almost 30 years old and out-of-date with respect to design codes, construction techniques, and the higher strength materials now commonly used.

Research Report 280 Effect on pavement wear of increased mass limits for heavy vehicles – stage 4

Published: | Category: Activity management , CAPTIF , Research programme , Research & reports | Audience: General

Accelerated pavement testing at CAPTIF (Canterbury Accelerated Pavement Testing Indoor Facility, Christchurch, New Zealand) was conducted between 2000 and 2004 on a standard two-coat chipseal that is typically used on New Zealand roads. This report is of Stage 4 of a 4-year accelerated pavement testing programme to assess the effects on pavement and surfacing life, should an increase in mass limits for heavy vehicles be allowed. Keywords: accelerated pavement testing, CAPTIF, heavy vehicles, loads, loading, mass limits, pavement, pavement loading, pavement performance, pavement wear, roads, road user charges, surface texture, thin-surfaced pavements, traffic, vehicles

Research Report 337 Deterioration of prestressed concrete bridge beams

Published: | Category: Activity management , Research programme , Research & reports | Audience: General

A routine inspection revealed significant corrosion of the prestressing strand on a concrete road bridge built in 1966 to a standard design used in about 117 State Highway bridges in New Zealand. To identify the cause of the deterioration and how many bridges of this design might be affected, the conditions of 29 similar bridges on New Zealand State Highways were evaluated by site investigation. The research, carried out in 2005–2006, found that although the concrete quality in the bridge beams was generally good, the combination of cover depths less than 25 mm and exposure to salt spray had increased the likelihood of corrosion in bridges of this design in the B2 (coastal frontage) exposure zone. Bridges in the B1 (coastal perimeter) and A2 (inland) zones are less likely to be affected, although the concrete in some of the beams contained chlorides added during construction.

Research report 403 The influence of surface treatments on the service lives of concrete bridges

Published: | Category: Activity management , Research programme , Research & reports | Audience: General

The corrosion of reinforcing bars and prestressing steel is the most significant risk to the durability of concrete road bridges in New Zealand. The application of water-resistant surface treatments has been suggested as a means of delaying corrosion damage. This research, carried out between 2007 and 2010, reviewed international research findings and the use of preventive surface treatments by road-controlling authorities in Australia, the UK, and North America, to develop a guideline for selecting appropriate surface treatments for delaying chloride-induced corrosion damage on concrete road bridges in New Zealand. The findings indicated that the effectiveness of surface treatments for reducing corrosion activity and extending service life depends not only on the chemical composition of the treatment, but also on the condition of the concrete substrate, the application process, and environmental exposure conditions. A process was developed to identify the potential benefits of such surface treatments for individual bridges and for...

Research Report 461 Characterisation and use of stabilised basecourse materials in transportation projects in New Zealand

Published: | Category: Activity management , Research programme , Research & reports | Audience: General

The stabilisation of near-surface granular pavement materials is accepted practice in transportation maintenance and capital development projects in Australasia. Stabilisation in this context involves the mechanical introduction of reactive agents, including cement and foamed bitumen, into existing or manufactured granular materials, with or without existing seal inclusion.

Research Report 305 Adaptation of the AUSTROADS pavement design guide for New Zealand conditions

Published: | Category: Activity management , Research programme , Research & reports | Audience: General

New Zealand granular pavement design is currently based on the assumption that all deformation of the pavement shape under traffic loading occurs in the subgrade. To reflect this theoretical behaviour the AUSTROADS document Pavement design – a guide to structural design of road pavements (AUSTROADS 1992) is based on limiting the vertical strain on the subgrade. AUSTROADS (1992) was adopted as a design methodology by New Zealand in 1996. In 2004 a newer version of the AUSTROADS guide was issued (AUSTROADS, 2004a) and this document is now the current pavement design guide in New Zealand. Just as with the 1992 document AUSTROADS (2004a) continues with the design methodology of minimising the subgrade strain according to the design traffic. This study, initiated in 2004, examines the design methodologies presented in AUSTROADS and evaluates them against available New Zealand research. Various subgrade strain criteria are examined for New Zealand conditions.
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