Grand Junction, Hampstead and Briens Road intersection upgrade

It was an absolute honour to be awarded the design consultancy and installation work for this $19 million intersection upgrade funded by the Federal and State governments. One of the more exciting projects to date as it allowed us to showcase one of our less known products, the Energy Absorbing Crash Cushion (EACC).

On average more than 63,100 vehicles travel through the intersection each day and there have been 91 crashes at the intersection in the past five years, including 28 casualty crashes. The upgrade will improve the safety of the intersection and will reduce congestion for motorists. IAS was again subcontracted by DPTI to design and install four EACCs at strategic locations around the intersection.

Figure 1. Grand Junction Rd, Briens Rd and Hampstead Rd intersection with four EACC locations

Energy Absorbing Crash Cushion (EACC)

The EACC is a type of road side barrier designed to attenuate and capture an errant vehicle in a frontal impact. They are usually deployed at vulnerable sites where:

  • Redirection of an errant vehicle results in additional risks to the road users

  • There are severe space constraints

  • Main risk is frontal impact due to approach trajectory

  • High speed environments where there is a likelihood of injury to vehicle occupants

  • Where tailored design is required for site layout

They consist of interconnected slotted steel tubes which are designed to provide controlled crumpling and energy absorption by an errant vehicle. This means they are readily repairable and are suitable for quick installation.

Grand Junction Road and Hampstead Road are key to freight movement and are often subject to heavy traffic. The key in improving congestion was to widen the roads approaching the intersection. In particular this required the demolition of several buildings, relocation of Stobie poles, road signs, phone boxes, underground services etc. However the larger Stobie poles could not be removed and some had to be left standing dangerously close to the road. This is a major safety concern as any vehicle impact with the poles can cause power outages, deadly traffic hazards and also kill the driver of the errant vehicle.

This is exactly where EACCs come in to rescue as they are perfectly adapted for constraining conditions. Each of the Stobie Poles on Grand Junction Rd has a unique orientation to the road and configuration of underground services and required a different design of the EACC.

Pole 1: Grand Junction Rd Bus Stop 29

Pole 2. Grand Junction Rd, Hampstead Rd slip lane

Pole 3. Grand Junction Rd before Austral Av intersection

Pole 4. Grand Junction Rd after Austral Av intersection

The versatility and robustness of the EACC is extended with IAS's pre cast concrete footings and years of experience in the road works field. We have found that water jet drilling with a vac truck usually delivers most efficient solutions while the pre cast concrete footings always save weeks of time.

Water jet drilling

Pre-cast footing