Gory Road, Cossack NT - 112827-20NT-RTR

Project description

The existing road profile of Gory road is based on a single lane (3m wide) sealed road, albeit badly deteriorated. About 550m is badly delipidated bitumen seal, followed by a damaged floodway and 100m gravel road to the last two property accesses. From Chainage 0 to 550m Gory road is a sealed road. The seal used to be about 3.5m wide, a profile for a single-vehicle width with unsealed shoulders of about 1m to allow passage. The seal appears to be of a 10mm single coat seal and is well beyond its design life. The seal is cracked, potholed and the edge of the seal severely jagged for its entire length. Road shoulder has eroded away, with an irregular depth of gravel present. The verges on both sides still have a vague resembles of a longitudinal swale, however, this is grassed and has no strong definition. At places it is flat and at level with the road. At chainage 550 – 650, a floodway exists in the road alignment. The current floodway is badly damaged. No damage could be observed on the downstream side along the concrete edge beam. However weeds are growing uncontrolled in the rock protection, rock layer is not graded with different sizes grouped in different locations and compacted, road seal has large potholes, with temporary infill with evidence of water ingress into the basecourse.

The present seal is a complete write-off. There is no benefit in patching or sealing the shoulders. The bitumen has lost its flexibility and bonding capacity. The original design allowed for a single vehicle to travel on a sealed surface. Traffic numbers were low and oncoming traffic could pass by putting a single wheel on the unsealed shoulder. Today, traffic count, as well as axle loads, have increased. The seal has deteriorated severely, and gravel shoulders were worn away, resulting in sharp edges and potholes in the bitumen. In addition, the bitumen has lost its flexibility and has become brittle. The design life span is normally 20-25 years, it is understood this has been well exceeded. Pritchard Francis recommends the bitumen to be milled and removed. We have allowed for a standard rural road design of a 6m wide sealed cross-section, with drainage on both sides. The damaged existing seal is to be cold-milled and worked into the pavement, which then becomes the subbase. A new basecourse pavement layer is to be constructed on top. The following will be the scope of works Chainage 0-550 o Install new hazard sign at Florina Road opposite Gory road termination o Reprofile the road, mill, and mix the defunct seal into the subbase. o Construct 150mm basecourse layer and profile o Construct 10mm bitumen single seal o Tie into the floodway o Cut V-drains on both sides along the entire road alignment, following the natural contour. • Chainage 550-650 o Construct floodway as per Tonkin design, with appropriate signage. o Inspect edge beams and assess on-site extend of scope to be constructed • Chainage 650-750 o Reprofile existing gravel road to 3% crowned profile o Construct 150mm basecourse layer and profile o Construct 10mm bitumen single seal o Tie into floodway at cha 650. o Construct a cul-de-sac turn around at cha 750 o Cut V-drains on both sides along the entire road alignment, following the natural contour

Project last updated: 14 Feb 2022