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Research Report 198 Comparison of accelerated pavement test facilities in New Zealand and Australia

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

This report presents the findings from a review of the operation and completed projects conducted at the Canterbury Accelerated Pavement Testing Indoor Facility (CAPTIF) and the Australian Accelerated Loading Facility (ALF). A test was undertaken at CAPTIF in 1999, where a granular material was imported from Australia and tested under CAPTIF loading. The material had been previously tested by ALF. The results from this test show that the performance of the material was similiar under loading by both devices, allowing for differences in the testing environments. The strengths and weaknesses of both facilities are compared and the possibilities for collaboration and technology transfer between the two facilities are explored. Keywords: accelerated pavement testing, pavement, granular materials evaluations

Research Report 084 Replication of VTI's stationary laser profilometer for measuring road surface profiles

Published: | Category: CAPTIF , Research & reports

The development and testing, during 1996, of a portable stationary laser profilometer and the associated analysis software is described. The instrument was developed and tested for measuring surface texture profiles of New Zealand roads to a higher resolution than is typically possible with vehicle-based systems. The instrument is similar to that which has previously been designed and developed by the Swedish Road and Traffic Research Institute (VTI). The Transit New Zealand laser profilometer provides the facility to carry out detailed analysis of road surface texture over the wavelength range of 0. 63 mm and 500 mm. The height measurement range of the equipment is to a maximum of 32 mm, and the length measurement range is to a maximum of 1. 7 m. Keywords: instruments, laser, mean profile depth, MPD, measurement, New Zealand, profile, profilometer, roads, road surface, texture

Research Report 463 Development of tensile fatigue criteria for bound materials

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

Flexural beam breakage and fatigue tests were conducted in 2008–11 to determine their relationships with pavement fatigue life and tensile strain for a range of New Zealand materials for use in pavement design of stabilised aggregates. The results showed that the tensile fatigue relationships from several fatigue tests under repetitive loading could be approximated by single flexural beam breakage tests. These relationships resulted in significantly longer pavement lives than the Austroads pavement design criteria but still predicted shorter fatigue lives than what actually occurred at the Canterbury accelerated pavement testing indoor facility (CAPTIF) test track, indicating some conservatism in the approach. Further research is required to validate the tensile fatigue design procedure against actual field data. Keywords: aggregates, basecourse, CAPTIF, fatigue, beam fatigue testing, modulus, pavement design, strain, tensile strain criteria, tensile strength

Research Report 207 Effect on pavement wear of an increase in mass limits for heavy vehicles

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

In order 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 is in itself not a problem provided that the charges accurately reflect the wear. At present (2001) road user charges are based on the fourth power law, which was developed from the AASHO road test 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 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 321 Epoxy modified open-graded porous asphalt

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

Investigations into the cohesive properties and oxidation resistance of an acid cured, epoxy modified open-graded porous asphalt (OGPA) were undertaken and an associated accelerated loading test carried out at Transit New Zealand’s CAPTIF facility. Results from the Cantabro test (a test of mixture cohesion relating to the resistance of OGPA to surface abrasion losses) indicated that the early life cohesive properties of cured epoxy OGPA should be comparable to that of standard OGPA at 25°C and markedly superior at 10°C. The modulus of the cured epoxy mixture was much higher than that of the standard OGPA but this is probably of little benefit given that failure through rutting and deformation is uncommon for properly designed OGPA. The superior oxidation resistance of the epoxy material was clearly evident in Cantabro tests conducted at both 25°C and 10°C.

Research Report 319 Benchmarking pavement performance between Transit's LTPP and CAPTIF programmes

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

This report details the findings from research conducted on the Long-Term Pavement Performance Programme (LTPP) and on the Transit New Zealand CAPTIF programme for accelerated pavement testing. The research was aimed at delivering a complete new model format to predict rut progression on New Zealand roads. It was based on earlier findings that suggested some limitations with the current approach using the World Bank’s HDM rutting models. A three-stage modelling approach is recommended:

Firstly, a simpler model is proposed to predict the initial rutting or densification. Average progression rates are proposed for the annual increase of rutting during the normal life of the pavement since no satisfactory model could yield any results which were more accurate. Lastly, a probabilistic model is proposed to predict the probability or risk of a pavement undergoing accelerated rut progression caused by weak layers or overloading.

Research Report 603 The relationship between vehicle axle loadings and pavement wear on local roads

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

In New Zealand heavy vehicles are charged for using the road based on the damage caused passing over the road. The current approach to charging has its origins in American research that found doubling an axle load increased the damage as a power function with an exponent of 4, known as the Fourth Power Law. This was developed with limited pavement and vehicle load types not representative of most of the roads in New Zealand. This research provided reliable evidence on the wear characteristics of New Zealand local road pavements from accelerated pavement loading studies at the Canterbury Accelerated Pavement Testing Indoor Facility (CAPTIF). The aim was to determine the relative damage on different pavement types/strengths. The data was extended with rut depth modelling with repeated load triaxial data and validated with field data from the nationwide long-term pavement performance sites.

Research Report 279 Effect on pavement wear of increased mass limits for heavy vehicles – stage 3

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

To improve the efficiency of the road transport industry, 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. New Zealand has a mass-distance road user charging (RUC) regime where the users pay for the road wear they generate, and therefore there is a need to accurately reflect the wear. Stage 3 of this study, carried out in 2002, aimed to accurately predict road wear from various levels of loading, an accelerated loading test was undertaken at the Canterbury Accelerated Pavement Testing Indoor Facility (CAPTIF) to compare the wear generated by different levels of loading.

Research Report 281 Effect on pavement wear of increased mass limits for heavy vehicles – concluding report

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

The road transport industry in New Zealand has been lobbying for increases in the allowable mass limits for heavy vehicles on the basis that this would give increased efficiency and benefits to the economy. Some of the proposals for increased mass limits involve increased axle load limits which would clearly lead to additional pavement wear. Road controlling authorities, while sharing the industry’s aims for increased efficiencies in the road transport system, are concerned that any additional pavement wear generated by higher axle loads will be paid for, so that the standard of the roading network can be maintained. At present (2005) Road User Charges (RUCs) are based on the fourth power law, which was developed from the AASHO road test 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.
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