Rural arterial road 5 km upgrade design.

Project overview

ASTCAD delivered civil design documentation for a 5 km arterial road upgrade in central NSW for a regional council. The scope included pavement reconstruction, geometric realignment of a tight bend, three intersection upgrades and full drainage replacement — all designed to Austroads and TfNSW specifications.

The challenge

The existing road had a non-compliant horizontal curve causing repeated heavy-vehicle rollovers. Realignment would impact a council-owned heritage stone wall and required environmental offset coordination. The drainage system was over capacity and contributed to recurring flooding of two adjacent properties.

Our approach

• 12d Model corridor design with full pavement and geometry
• Horizontal curve realignment minimising heritage stone wall impact
• Drainage design with capacity for Q100 and provision for upstream catchment
• Three intersection treatments — channelised, auxiliary lane and seagull
• Pavement design to Austroads AGPT04 with subgrade testing

Deliverables

• Detailed design drawings (62 sheets)
• Pavement design report per AGPT04
• Drainage design report and capacity analysis
• Signage and line-marking plans
• Construction specification and bill of quantities

Outcome

The upgrade was constructed in two stages over 8 months. Post-completion road audit confirmed elimination of the geometric hazard. The drainage upgrade resolved flooding incidents at both properties; no further insurance claims have been raised.

How we approach rural road upgrade design

A rural road upgrade design is constrained by what already exists — property boundaries, services, floodways and the traffic that must keep moving during construction. We start from survey and design the horizontal and vertical geometry to Austroads guidelines for the target speed environment, widen formations where safe overtaking or heavy-vehicle movements demand it, and design pavements from the geotech CBR data rather than assumption. Drainage upgrades — table drains, culvert renewals, floodway levels — are integrated with the road geometry, and construction staging is documented so the road can stay open under traffic management throughout the works.

Road upgrade documentation

Deliverables include plan and longitudinal sections, typical cross sections and pavement details, intersection and property access details, drainage plans with culvert schedules, signage and line-marking plans, and staging diagrams for constructability. The set is prepared to the road authority’s drafting presentation standards so review cycles are short, and we carry the design through construction-phase queries when the contractor hits the inevitable in-ground surprise.

Designing around live traffic

Rural road upgrade design happens on roads that cannot close, so constructability under traffic shapes the design as much as geometry does. We document staging that maintains sealed running lanes at every phase, design temporary tie-ins with real attention to their geometry — a lumpy temporary connection at 100 km/h is a hazard, not an inconvenience — and coordinate drainage staging so half-built culverts do not flood the open lane in a storm. Speed environment through the works, sight distance at staged intersections and haul route pavement impacts are all documented, giving the contractor a design that can actually be built the way it was drawn.

We document rural road upgrades for councils and their contractors across regional Australia, from single-culvert renewals to multi-kilometre arterial widening. If your project has survey and geotech in hand, we can usually begin geometry design within days and structure the deliverables around your funding milestones.