Glenview Estate Subdivision

1. AustStab Awards of Excellence 2014 Glenview Estate Subdivision Mid Coast Road Services Innovation or Excellence in Sustainability Sponsored by

2. Objectives • Investigate options to reduce the cost of pavement construction through subgrade improvement, on a medium sized residential subdivision • King and Campbell were consulted regarding subgrade improvement initiatives available

3. Existing design • Previous testing had subgrade CBRs of 3 • Original design was • 300mm select layer above • 100 DGS20 • 100 DGB20 • Existing subgrade exhibited swelling –indicated a low wet strength

4. New Design New testing undertaken including lime demand testing at 2% and 4% HL Trials indicated soaked CBRS of 17-40 Resulting pavement design required stabilizing at 300mm of Hydrated Lime at 2%. Post testing achieved CBRS of over 25.

5. Existing subgrade CBR 3

6. Existing subgrade Road 2

7. Dry Mix Road 1

8. New Pavement Design • Pavement redesigned at CBR 15 • Select layer was removed • Pavement reduced to • 150mm DGS • 130mm DGB • 40mm AC14

9. Benefits • Reduced duration of project by 2 weeks • Minimised impact to local residents • Cost savings of $10/m2 over 4,000m2 • Eliminated requirement to import fill • Eliminated requirement to remove 1200m3 of material to the tip site

10. Outcomes • Sustainability • Reduced the volume of imported fill • Reduction in vehicle movements • Used existing subgrade material

11. Timeframe Reduction in project duration from 22 weeks to 20 weeks

12. Economical Cost savings delivered back to client Savings of $10/m2 in first stage

13. Environmental Elimination of select layer approx 3,000t Reduced traffic movements on existing road network Reduced noise impact to residents near site