Toolkit and Mindset: Design Guidance for Road Drainage in Auckland Transport
Stormwater Conference
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Auckland Transport Code of Practice (ATCOP) aims to align design process with issues and outcomes for SW management in Auckland. The Plans, Codes and Guidelines proposed for Auckland are described.
A new approach to defining design objectives is set out –
Quality management design: deals with frequent rainfall for contaminants, volume reduction, and attenuation.
Serviceability management design: Rainfall run-off managed within the road reserve for acceptable levels of service for road users, limiting hazards and nuisance.
Major event management design: Effects of infrequent severe conditions managed to ensure survivability or recovery of infrastructure, accessibility for emergency services and protection of personal safety and property.
ATCOP will require designers to address all these objectives in road drainage designs. This should set designers to think of LID, of surface water shedding and collection, and of effects of flooding when preparing designs.
Road engineers need little new guidance on conventional catchpit and pipe design. ATCOP focuses on LID, to ensure that roads are planned for natural process drainage as far as possible.
Operation and maintenance plans are required. These will allow operational issues to be described, and whole life costs to be evaluated when choosing between alternative solutions.