OVERVIEW
As part of Main Roads efforts for continuous improvement, industry professionals have reviewed the current Main Roads practices for contracting work. In response to issues raised, WARRIP launched an investigation to determine what could be done to improve WA practices. Comparisons to approaches taken by other state road authorities helped to reveal some potential solutions and where further study would be beneficial.
SUMMARY
Due to the forecast high capital investment by Main Roads WA in construction of new heavy-duty pavements, WARRIP reviewed current pavement engineering practices for large-scale/complex road projects, actively seeking input from both the design and construction industry.
APPROACH
- Workshop with contractors and pavement designers to identify issues regarding contracting forms and requirements, project scoping documents (SWTC), design guides, pavement materials and other relevant issues
- Review of major project pavement types and construction specifications used across Australia
- Review of alternative pavement material technologies identified in workshops and the current use of these materials nationally
CONTRACTORS AND PAVEMENT DESIGNERS WORKSHOP
These workshops highlighted that open discussion and background information improve collaboration, which could be done via various knowledge transfer activities. Contractors are also looking for different forms of contract that reallocate risk, enabling more innovative solutions. After further analysis, WARRIP identified the primary issues to be investigated were:
- What pavements are permitted and used?
- How are they are designed?
- What warranty/defects liability processes are appropriate?
REVIEW OF HEAVY-DUTY PAVEMENT TYPES ACROSS AUSTRALIA
| Pavement Type | WA | NSW | QLD | VIC | SA |
|---|---|---|---|---|---|
| Full depth asphalt | Commonly used | Commonly used | Commonly used | Commonly used | Commonly used |
| Deep strength asphalt | Not used | Commonly used | Selectively used, previously most common type >10 years ago | Commonly used | Rarely used, previously common type >8 years ago |
| Thin asphalt on granular | Commonly used | Not permitted as a heavy-duty pavement type | Not permitted as a heavy-duty pavement type | Not permitted as a heavy-duty pavement type | Not permitted as a heavy-duty pavement type |
| Thick asphalt over lean mix concrete (composite pavement) | Not used | Commonly used | Rarely used | Not used | Not used |
| Hydrated cement –treated crushed rock base (HCTCRB) | Selectively used if prerequisites satisfied | Not used | Not used | Not used | Not used |
| Concrete pavements – PCP, CRCP, JCRP, SFRC | Limited use | Commonly used | Selectively used, particularly in tunnels and busways | Rarely used | Rarely used, but first major use underway |
| Spray seal on granular | Commonly used on rural highways; not permitted on urban projects | Commonly used on rural highways; not permitted on urban projects | Commonly used on rural highways; not permitted on urban projects | Commonly used on rural highways; not permitted on urban projects | Commonly used on rural highways; not permitted on urban projects |
EMERGING TECHNOLOGIES AND FUTURE INNOVATIONS
Emerging technologies and future innovations cited during the workshops included:
- EME2 Asphalt (see WARRIP 2016-001)
- Increased Reclaimed Asphalt Pavement(RAP) Utilisation (see WARRIP 2017-002)
- Crumb Rubber Asphalt (see WARRIP 2016-012)
- Stone Mastic Asphalt (SMA) (see WARRIP 2016-002)
- Performance Based Specifications for Road Construction Materials
- Foam Bitumen Stabilisation
- Potential Use of Nanotechnology (see WARRIP 2018-005) As indicated, some of these emerging technologies were or are currently under investigation by WARRIP.