Project description

The project brief was to:

• remove the roundabout and install traffic signals
• install signal-controlled pedestrian crossings
• widen the road and create additional traffic lanes
• create right-turn lanes on each of the approaches
• install CCTV cameras.

Challenges

The project required minimal disruption to pedestrian and vehicle traffic, particularly as a number of local businesses depended on easy access from passing traffic. RFS was also required to construct stormwater drainage, relocate existing utilities and complete the works with asphalt paving and line marking. RFS developed variations on standard work methods to protect some heritage-listed buildings in the area. Those challenges were addressed by RFS in a number of ways.

Traffic management

The intersection carries very heavy traffic in all directions. RFS needed to maintain road capacity and minimise interruption to traffic. This was achieved by staging four separate traffic arrangements – shifting the traffic lanes laterally four times and creating four temporary roundabouts at set stages of the project. Both day and night shifts were operated to minimise traffic disruption.

So as not to disrupt pedestrian movement, temporary footpaths were created between property boundaries and work areas with Paraweb fencing and sign-posting.

The operation to remove the old roundabout, commission the traffic signal controller and replace the line marking was completed in one night. This took considerable planning as well as constant communication with the local community to keep them informed about changing traffic conditions.

Access to homes and businesses maintained

It was critical to maintain access to residences and businesses during construction. It was achieved by staging the pavement widening in small sections to ensure ongoing access for local residents. We also provided temporary secure parking while paving went on.

Signs were provided in front of businesses to direct customers into their parking areas. Pavement widening was staged so that there was always access to business premises via side streets.

Utility relocations

While the traffic above ground was bad enough, below ground there was congestion of another kind with water and sewerage mains, high-pressure gas pipelines and electricity and telecoms cables all competing for space with the tree roots. We undertook a significant amount of under-boring – to a depth of four metres in places – to get under culverts and avoid the occasional seams of ironstone.

Considerable work went into coordinating utility contractors to prevent one obstructing another.

Protecting heritage buildings

RFS conducted dilapidation surveys before work started to assess the existing condition of all nearby properties and in particular, a group of heritage houses adjacent to the pavement widening areas. To reduce the risk of vibration damage we used multi-tyred pneumatic rollers (instead of smooth drum) and a sand-cement mix instead of sandstone in the select fill layer.