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Research Report 259 Relationship between design and predicted performance of New Zealand pavements

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

Both the design of new pavements in New Zealand and their rehabilitation treatments are currently performed in accordance with the Austroads Pavement Design Guide and its New Zealand Supplement. New Zealand is also adopting pavement deterioration modelling based on the World Bank HDM models. This report demonstrates how the modelling of roughness progression can supplement this pavement design. Keywords: Austroads, CIRCLY, database, design, HDM III, modelling, New Zealand, pavement, pavement design, performance, road

Research Report 325 The effect of grading on the performance of basecourse aggregate

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

A laboratory study was undertaken to determine the effect of grading/particle size distribution on permanent deformation in multi-stage repeated load triaxial (RLT) tests. Results showed the coarse gradings with a Talbot’s exponent n-value of 0. 8 had the least amount of permanent deformation for high-moisture contents near saturation. Finer gradings with an n-value of 0. 3 had the least deformation in all of the tests in dry conditions at less than 70% of optimum moisture content. Similar performance in terms of permanent deformation was obtained if variations of the n-value were less than 13%. Based on limiting the variations in n-value to ± 13% new grading envelopes for use in the new Transit New Zealand specification for RLT testing were proposed.

Research Report 324 Evaluating the network condition changes of transit networks managed under PSMC procurement options

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

Performance specified maintenance contracts (PSMC) have been operational in New Zealand for more than six years. These contracts are driven by key performance measures (KPMs) that are used to define the expectations of the road agencies and monitor the progress and performance of the contractor. As the effectiveness and efficiency of the KPMs is vital for achieving the desired results, it is essential to examine the effectiveness of the current KPMs in controlling and directing the maintenance contracts. The report examines the interpretations of the collected data using average and mode. The poor representation of the total network condition by the traditionally used average is illustrated by numerous examples. Alternative representation of the network condition is proposed and illustrated by using the mode of the data set.

Research Report 075 A framework for an ideal road structures design manual

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

The report presents a definition of the scope and coverage of an ideal manual for the design of roading structures to meet the needs of Transit New Zealand and compares the present Transit New Zealand Bridge Manual and the 1992 Austroads Bridge Design Code with each other and the ideal manual. Recommendations are made on which document to adopt as the basis for future development of a roading structures design manual, and on the adoption and development of criteria for revision of the manual. Keywords: Bridge, code, manual, road structure

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 199 Methods for determining structural number of New Zealand pavements

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

The structural number (SN) of a road pavement is a method for describing the strength of a road pavement, in pavement deterioration models that are currently being calibrated for New Zealand road conditions. To assist in the development of these models in New Zealand, and in implementing them in pavement design software, an investigation was carried out between 1999–2000, into the sensitivity and precision of the methods of obtaining the Structural Number. The methods used are either direct, by CBR or modulus measurements of each layer in a pavement, or indirect, generally based on deflections of the entire pavement. Correlating direct against indirect methods, and the limitations of the correlations, are discussed. Spatial variability of SN on typical pavements in New Zealand, the number of tests required to characterise SNP to different levels of precision, and predicting SNP for subgrades from volcanic materials were investigated.

Research Report 002 Communicating about use of road aggregates

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

A limited survey of roading practitioners was carried out to determine their opinion and needs with respect to communicating the findings of research about the properties of unbound aggregates. This survey was then used as a basis for the formulation of a strategy. It was found that the needs of the different groups within the road construction industry varied. Methods of communication have to be tailored to suit each group. The strategy comprises:

Preparation of text to identify and describe the important aspects of pavement construction. Commission of video to record the requirements for a stable pavement, production of suitable aggregates, correct methods of construction, and criteria that control performance of a pavement. Fostering lectures, seminars, discussion groups, workshops and in-house training. Provide support staff, course material and videos as appropriate. Keywords: Aggregates, roading, communication

Research Report 599 Review of the NZ Transport Agency treatment selection algorithm

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

The objective of this research, carried out between 2012 and 2015, was to improve the treatment selection algorithm (TSA). The TSA is used to forecast the timing and treatment type of works required to maintain roads in good condition for the least whole-of-life cost in the short to medium term. The output was a candidate list of sites intended for validation in the field combined with recommended drainage improvements and funding estimates. Since the TSA was developed, the long-term pavement performance monitoring sites have yielded much practical information; pavement and surface condition measurement techniques and parameters have developed; and economic analysis parameters have changed. The algorithm, used to guide future surface and pavement works, needs to be updated to reflect current knowledge and recent experience. Recommended improvements include the consideration of thin asphaltic surfacings and maintenance cost data.

Research Report 074 Non-traditional materials for trench and bridge abutment backfill

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

An overview of non-traditional backfill materials has been compiled from material identified in an international literature search carried out in 1992. Materials considered include controlled low strength materials (CLSM), foamed concrete, fly ash, wood waste, expanded polystyrene (EPS), and various miscellaneous materials. General information as well as composition, properties, advantages, limitations and typical applications are pr4esented for each material. The properties determine the backfilling application to which each material is best suited. Most of these materials have potential for use in New Zealand provided their advantages and limitations are recognised and understood by would-be users. Keywords: Backfill, bridge abutment, bridges, flowable materials, foamed concrete, fly ash, New Zealand, pavement, polystyrene, roads, trench, tyres, wood waste

Research Report 195 Emulsion modification of unsealed road pavements

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

This report reviews South African experience of modifying aggregates with bitumen and a trial use of bitumen to modify two unsealed roads in the Central Otago district. The test programme consisted of laboratory tests and NAASRA roughness counts and field observations. Initial observations on the trials and control sections indicated that surface wear of the pavement will steadily increase the roughness of the road to a point within five years where additional maintenance work will be required to restore the surface and ride. Modified aggregates resulted in reduced maintenance costs with a significant reduction in grading and dust. These trials indicate that bitumen modification is generally less economic over the longer term than conventional seal extension particularly where aggregates are obtained at low cost. Keywords: bitumen modification, lime, foam, bitumen, unsealed roads, Central Otago, New Zealand