Chapter 3Risk management#

What is the proposed departure?#

Only one lane will remain open in the affected direction while works are being undertaken. The proposed departure reduces the width of this lane to 2.9 m to allow a 1.2 m lateral clearance and avoid the use of barrier separation.

What alternatives have been considered?#

Maintain the existing lane widths and install temporary barriers.

What are the costs and impacts of the standard arrangement and Exception (including environmental, community, network and safety impacts along with any other relevant factors and constraints)?#

Due to the day-time traffic demand, the works will be carried out between 9 pm and 5 am. A lane closure during day-time peak period would result in considerable traffic congestion and the time and cost required to implement a full detour is not considered justifiable due to the short duration of the works.

The set-up and removal of barriers will add several hours to the duration of the works and prevent it from being completed in one nightshift. This will result in additional night-time noise for surrounding residence, additional traffic impacts, and considerable additional costs in the supply and installation of barrier as well as additional traffic management and construction worker labour.

While a reduction in lane width is generally considered to be associated with reduced capacity and safety, this will be managed through the undertaking of works at night when volumes are low and adequate advance warning and speed restrictions at the work site. A 2.9 m lane provides adequate width for all heavy vehicles that have general access to the road. The road is not an over-dimension route.

What mitigation treatments were identified in the risk assessment in relation to this Exception?#

The following mitigation measures have been identified in relation to this Exception:

• Ensure advance signage is in accordance with Queensland MUTCD Part 3 and the QGTTM and correct for the works taking place.
• Delineate with suitable bollards/hats to clearly identify locations.
• Reduce the posted speed to 40 km/hr to reduce the likelihood, impact and severity of crashes and further ensure the safety of road workers.
• Ensure speed signage arrangements are correct so police enforcement can be undertaken.
• Monitor road user behaviour to determine if drivers are observing and responding to signs and devices. If not, review treatments.
• Maintain acceptable minimal lateral separation from the trafficable path of 1.2 m.
• Advise appropriate authorities of width reduction so over dimension vehicles can be diverted.
• Provide warning of diversion at closest decision point.

What is the safety performance of the standard arrangement?#

The safety performance of the standard lane width applied in conjunction with Queensland MUTCD and QGTTM compliant signs and devices is considered to be very good.

What is the expected safety performance of the arrangement that incorporates the Exception (including performance information from other sites where the Exception has been applied)?#

All other arrangements are in accordance with the relevant standards. The 2.9 m lane has a 1 m concrete median providing clearance to opposing traffic on one side and a 1.2 m clearance to workers on the other side. For this reason, the safety performance of the arrangement incorporating the Exception is considered to be comparable to the standard arrangement incorporating a 3 m lane.

Is the difference acceptable?#

Yes.

1.4Roles and responsibilities#

Exceptions to temporary traffic management standards must be certified by a Registered Professional Engineer of Queensland (RPEQ), who must verify that the Traffic Guidance Scheme is compliant with reasonable engineering principles and that the departmental Exception processes have been followed.

1.5Monitoring and evaluation#

Monitoring of road works sites where Exceptions have been implemented must be carried out for the duration of the works to ensure they are performing safely, effectively and with an acceptable level of service. This monitoring can be incorporated into the daily routine checks required by the Queensland MUTCD and QGTTM. Clear and complete records of the monitoring undertaken, analysis of results and any changes made to the TGS as a result must be kept.

Details of any incidents that occur at the site, whether the Exception contributed to the incident and the actions taken, are also essential.