Roads & Transport Determination of the intervention point for rehabilitation of dense graded asphalt wearing courses – the Western Australian experience Martyn Glover Sponsored by Determination of the intervention point for rehabilitation of dense graded asphalt wearing courses – the Western Australian Experience. Author: Martyn Glover Introduction Perth, Western Australia Isolated City 2,138Km from Adelaide 5,441Km from Rotorua Minimal research but good data MRWA is central repository Papers purpose is to present the final findings of a significant study which develops a intervention point and subsequent life cycle for asphalt wear courses in the Perth metropolitan area. Study Area Perth Metropolitan Area Swan Coastal Plain Wanneroo in north to Mandurah in south and Mundaring to the East. Participating Local Governments 30 metropolitan Local Governments were invited to be part of the study. 14 Local Governments provided permission to use their data. Participating Local Governments Divided into three distinctive geological areas: Perth Coastal including Belmont, Cottesloe, Joondalup, Melville, Nedlands, South Perth and Wanneroo. Darling Scarp including Armadale, Gosnells, Kalamunda and Mundaring. Murray Coastal including Mandurah and Rockingham. Collectively the participants have 9,378Km of sealed roads which provides a significant dataset Swan Coastal Plain 30 Km wide strip Cape Naturaliste in the south to North of Perth Indian Ocean to the west and Darling Scarp to the east Predominantly sand Bassendean sand Spearwood sand (Tamala Limestone) Quindalup sand (Safety Bay Sand) Study Data Sets Roman II Road management System utilised by 134 of 140 of Local Governments in WA Data collected includes road lengths, construction dates, resurfacing dates and road condition Provided asset management tool for WA Local Government since the 1970’s Provides for road data as far back as 1914 which was a Macadam pavement in Cottesloe WALGA Report on Local Government Road Assets and Expenditure provides data on road lengths, road condition and annual expenditure ARRB Field Studies between 2003 and 2007 Road Pavements High quality sub-grades Ultra-thin pavements Local Government Guidelines for Subdivisional Development Minimum Standard The Guidelines prescribe the anticipated design life of pavements as follows: Unless specified otherwise by the local government, the permanent deformation of the granular pavement must have a minimum design life of 40 years. Unless specified otherwise by the local government asphalt must have the following minimum design life: open graded asphalt – 10 years; dense graded asphalt 50 millimetres total thickness or less – 20 years fatigue life; and dense graded asphalt greater than 50 millimetres total thickness – 40 years fatigue life. The Guidelines provide three typical pavements ranging from: 250mm to 280mm thick including an asphalt layer between 25mm and 65mm thick overlaying an unbound base of crushed rock and/or crushed limestone between 200mm and 250mm thick. Asphalts In the past all wear courses were 10mm dense grade asphalt at 25mm thick and manufactured with class 170 bitumen More recently use both dense grade or stone mastic asphalts with thicknesses at 30mm up to 40mm Most Local Governments use the IPWEA/AAPA Technical Specification, Tender Form and Schedule for Supply and Laying of Hot Asphalt Road Surfacing Climate Mediterranean Climate promotes longevity of road pavements Temperature Average Max 24.7oC Average Min 12.8oC Seasonal Rainfall Average 734.1mm per annum Average Period of 104.1 days per annum No Freeze/Thaw Climate change By 2100 rainfall decreasing Participating Local Governments’ Road Networks Length of Asphalt Road Totals Group Local Government Sealed Road Area Reseal Percentage Area (m2) (km) (m2) Resealed Swan Coastal Plain City of Belmont 229.28 220890 67350 30.49% Town of Cottesloe 48.47 29120 22780 78.23% City of Joondalup 1009.64 2627560 89785 3.42%* City of Melville 733.65 521344 189480 36.34% City of Nedlands 147.00 131210 173290 132.07% City of South Perth 197.77 193480 38250 19.77% City of Wanneroo 1291.52 1028770 147140 14.30% Murray Coastal Group City of Mandurah 667.16 441322 9140 2.07% City of Rockingham 961.42 895201 46722 5.22% Darling Range Group City of Armadale 683.66 549108 103567 18.86% City of Gosnells 855.05 689125 147564 21.41% Shire of Kalamunda 645.00 209450 100240 47.86% Shire of Mundaring 602.75 129200 122970 95.18% City of Swan 1306.97 691640 139117 20.11% Road Network The older Local Governments (100 years) have statistically resealed most or all of their roads The younger Local Governments have replaced proportionately less There can be anomalies as is the case with the split of Joondalup and Wanneroo The average proportion of reseals across the data set was 16.7% of the road network WALGA Local Government Road Assets and Expenditure reports on the condition rating and expenditures of WA Local Governments on their road networks WALGA Key Financial Indicators Road Condition (Written Down Value/Current Replacement Value) Preservation Performance (Actual Expenditure/Status Quo Cost) Road Condition Indicator =WDV/CRV Road Condition Group Local Government 2000/012001/022002/032003/042004/052005/062006/072007/082008/092009/102010/112011/12Average Swan Coastal Plain City of Belmont 0.65 0.66 0.66 0.66 0.65 0.65 0.66 0.66 0.75 0.75 0.76 0.76 0.69 Town of Cottesloe 0.67 0.65 0.65 0.65 0.65 0.64 0.65 0.67 0.64 0.64 0.56 0.56 0.64 City of Joondalup 0.79 0.81 0.81 0.81 0.81 0.81 0.80 0.70 0.65 0.65 0.68 0.69 0.75 City of Melville 0.69 0.68 0.67 0.67 0.67 0.67 0.68 0.66 0.56 0.56 0.58 0.58 0.64 City of Nedlands 0.67 0.65 0.65 0.65 0.65 0.65 0.66 0.66 0.64 0.64 0.54 0.54 0.63 City of South Perth 0.69 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.67 0.67 0.70 0.70 0.68 City of Wanneroo 0.75 0.74 0.74 0.74 0.73 0.73 0.74 0.71 0.77 0.77 0.79 0.79 0.75 Averages 0.70 0.70 0.69 0.69 0.69 0.69 0.70 0.68 0.67 0.67 0.66 0.66 0.68 Murray Coastal GroupCity of Mandurah 0.75 0.64 0.75 0.75 0.75 0.75 0.75 0.68 0.67 0.68 0.77 0.77 0.73 City of Rockingham 0.74 0.74 0.74 0.74 0.74 0.74 0.74 0.67 0.82 0.82 0.75 0.75 0.75 Averages 0.75 0.69 0.75 0.75 0.75 0.75 0.75 0.68 0.75 0.75 0.76 0.76 0.74 Darling Range Group City of Armadale 0.70 0.68 0.69 0.69 0.69 0.69 0.68 0.68 0.73 0.73 0.74 0.74 0.70 City of Gosnells 0.70 0.70 0.70 0.70 0.70 0.69 0.69 0.64 0.71 0.71 0.68 0.68 0.69 Shire of Kalamunda 0.71 0.69 0.70 0.70 0.70 0.69 0.69 0.68 0.72 0.72 0.72 0.72 0.70 Shire of Mundaring 0.70 0.70 0.70 0.70 0.70 0.70 0.69 0.60 0.60 0.60 0.62 0.62 0.66 City of Swan 0.71 0.70 0.69 0.69 0.70 0.69 0.68 0.64 0.62 0.63 0.68 0.68 0.68 Averages 0.70 0.69 0.70 0.70 0.70 0.69 0.69 0.65 0.68 0.68 0.69 0.69 0.69 Road Condition Indicator Highest value is 0.79 at the City of Wanneroo, currently the fastest developing Local Government and consequently the most new roads Lowest value is 0.54 at the City of Nedlands which has some of the oldest pavements in WA Average indicator is around 0.70 which could be utilised as the preferred level for Road Condition in metropolitan Perth Based on the data, the average road condition for the participating LG’s is meeting the proposed level at current intervention levels Preservation Performance = Actual Expenditure/SQC Preservation Performance Group Local Government 2000/01 2001/02 2002/03 2003/04 2004/05 2005/06 2006/07 2007/08 2008/09 2009/10 2010/11 2011/12 Average Swan Coastal Plain City of Belmont 1.76 1.59 1.29 1.12 1.10 1.23 1.03 0.87 1.27 1.43 1.56 1.62 1.32 Town of Cottesloe 1.66 2.38 2.48 2.26 1.75 1.94 1.64 1.88 1.77 1.73 1.67 1.79 1.91 City of Joondalup 0.91 0.96 0.93 0.90 0.71 0.81 0.49 0.53 0.79 0.81 0.95 1.03 0.82 City of Melville 1.32 2.04 1.04 0.83 0.87 0.88 0.93 0.92 1.02 1.00 1.53 1.28 1.14 City of Nedlands 2.47 2.90 2.16 2.24 2.07 2.04 1.35 1.71 2.19 1.93 2.26 2.13 2.12 City of South Perth 0.32 1.35 1.11 0.88 0.83 0.71 0.91 1.00 1.32 1.24 1.22 1.63 1.04 City of Wanneroo 0.68 0.70 0.66 0.63 0.60 0.44 0.55 0.58 0.48 0.47 0.57 0.49 0.57 Averages 1.30 1.70 1.38 1.27 1.13 1.15 0.99 1.07 1.26 1.23 1.39 1.42 1.28 Murray Coastal Group City of Mandurah 0.81 0.85 0.79 0.78 0.76 0.46 0.46 0.49 0.71 0.77 0.65 0.80 0.69 City of Rockingham 0.65 0.56 0.63 0.65 0.51 0.61 0.78 0.72 0.74 0.54 0.80 1.06 0.69 Averages 0.73 0.71 0.71 0.72 0.64 0.54 0.62 0.61 0.73 0.66 0.73 0.93 0.69 Darling Range Group City of Armadale 1.09 1.26 1.08 1.27 1.16 0.97 1.01 0.85 0.97 0.88 0.52 0.73 0.98 City of Gosnells 0.46 0.85 0.78 0.90 0.57 0.69 0.61 0.58 0.81 0.96 0.91 0.84 0.75 Shire of Kalamunda 0.67 0.71 0.80 0.72 0.72 0.53 0.72 0.83 0.56 0.62 0.60 0.42 0.66 Shire of Mundaring 0.92 1.02 0.88 0.83 0.78 0.65 0.68 0.73 0.91 0.85 0.71 0.87 0.82 City of Swan 0.87 0.72 0.83 0.88 1.07 0.92 1.04 1.02 0.90 0.90 1.05 1.31 0.96 Averages 0.80 0.91 0.87 0.92 0.86 0.75 0.81 0.80 0.83 0.84 0.76 0.83 0.83 Preservation Performance Fully developed Local Governments are required to spend more of their own funds to maintain the road to the required condition The developing Local Governments can spend less because so much of their network is new and funded by developer Actual Expenditure per lane kilometre Expenditure per Lane Km in $,000s (Built up Areas) Group Local Government 2000/01 2001/02 2002/03 2003/04 2004/05 2005/06 2006/07 2007/08 2008/09 2009/10 2010/11 2011/12 Average Swan Coastal Plain City of Belmont $13,730 $13,165 $10,105 $8,966 $8,933 $11,033 $9,907 $9,240 $10,242 $11,524 $12,019 $13,663 $11,044 Town of Cottesloe $9,715