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Displaying Page 3 of 64

Research Report 517 Use of roadside barriers versus clear zones

Published: | Category: Safety, security and public health , Research programme , Research & reports | Audience: General

This report summarises research carried out in 2011–12 to quantify the effects of roadside barriers and clear zones on mitigation of run-off-road crash numbers and crash severity for New Zealand road and roadside characteristics through statistical and computer simulation modelling. The purpose of the research was to provide practitioners with information that would allow them to make safe, more appropriate and cost-effective treatments for specific conditions.

Research Report 335 Performance tests for road aggregates and alternative materials

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

Aggregates used as base materials in thin-surfaced granular pavements common to New Zealand contribute at least half the wheeltrack rutting and roughness seen at the surface. Currently, no reliable cost-effective measure of an aggregate’s resistance to rutting in specifications exists. Several test methods using the repeated load triaxial (RLT) apparatus were investigated for use in specifications for basecourse aggregates. Rut depth prediction methods and pavement finite modelling were applied to the RLT results to determine traffic loading limits for the aggregates tested. It was found that the average slope from the six-stage RLT test was the best predictor of traffic loading limit and this test was recommended for use in basecourse specifications.

Research Report 393 Relative costs and benefits of modal transport solutions

Published: | Category: Environmental impacts of land transport , Research programme , Research & reports | Audience: General

This report describes the outcomes of a study commissioned by the NZ Transport Agency to inform local authorities about the costs and benefits of transport modes. The aim of the study has been to provide general advice on the relative cost and benefits of alternatives with a focus on passenger transport in urban areas.

Research report 450 Evaluation of the value of NZTA research programme reports to end users

Published: | Category: About the research programme , Research programme , Research & reports | Audience: General

This evaluation assesses how valuable the findings of NZ Transport Agency research reports, published from 2005 to 2009, have been for end users in New Zealand. The evaluation also identifies the barriers and enablers that make the difference between successful and less successful uptake and use of findings from the research reports, and the extent to which current Transport Agency mechanisms for disseminating and promoting research findings represent the best possible use of available resources.

Research Report 508 Improvement of the performance of hotmix asphalt surfacings in New Zealand

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

This research project had the objective of identifying areas where changes could be made in the use of thin layers of asphalt so that improvements in performance could be obtained. The project was not designed to investigate quality issues, but was to concentrate on materials and selection. The project was initiated because the NZ Transport Agency had found that costs of resurfacing using asphalt had escalated and the lives being achieved appeared to be short. This research in this report, which was undertaken between 2007 and 2012, investigated the following areas:

Research Report 231 Increase in mass limits effect on pavement wear – stage 2

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

To improve the efficiency of the road transport industry in New Zealand, a range of mass limit increases for heavy vehicles has been proposed. Some of the options for mass increases include increasing the axle load limit, which would inevitably lead to increased road wear. As New Zealand has a mass-distance road user charging regime where the users pay for the road wear they generate, this increased wear is in itself not a problem provided that the charges accurately reflect the wear. At present, road user charges are based on the fourth power law, which was developed from the AASHO road test carried out in the United States in the 1950s. The pavements and vehicles used for that test differ considerably from those in use in New Zealand today.

Research Report 290 Road surface texture measurement using digital image processing and information theory

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

This report details the progress made in tests in Oklahoma, USA ,and Christchurch, New Zealand, during the period August 2004 to June 2005, exploring digital imaging technology to measure chipseal surface texture. It details the research methodology to develop a technology to replace the sand circle test as a means to measure chipseal surface texture more accurately and safely. The project used digital imagery and exploited ‘information theory’ to develop a quantitative relationship between texture measured by the sand circle test and the fast Fourier transform of a digital image of the surface taken at the same spot as the test. The preliminary correlation achieved and reported in the interim report has been confirmed by a larger group of data collected after the interim report was written. A reliable statistical correlation using linear regression analysis with a coefficient of determination of 80% between digital image processing output and sand circle...

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 404 Environmental and financial costs and benefits of warm asphalts

Published: | Category: Environmental impacts of land transport , Research programme , Research & reports | Audience: General

Warm asphalts are asphalts produced at significantly lower temperatures than the C that is typical of a hot mix plant. Depending on the approximately 160 technology used, laying and compaction may also be possible at significantly reduced temperatures. The report gives a summary of current warm asphalt technologies, followed by details of costs, temperature reductions and energy savings. A comparison is made of potential environmental costs and benefits of hot mix manufacture and the different warm mix methodologies.

Research Report 462 Lifetime liabilities of land transport using road and rail infrastructure

Published: | Category: Environmental impacts of land transport , Research programme , Research & reports | Audience: General

The aim of the project was to establish the whole-of-life environmental performance of passenger and freight movement that uses roads and rail. The performance indicators selected were life cycle energy consumption, life cycle stormwater contamination, and life cycle GHG emissions. This study was based on process assessment and considered material use, transport requirements, on-site machinery use, and fuel use. The impacts of traffic delays and rolling resistance were not considered. The study was undertaken in New Zealand between October 2009 and March 2011 using data for the year beginning July 2007 and ending June 2008.
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