Frequently Asked Questions - Supplement to Austroads Guide to Road Design Part 1

The updated Road Planning and Design supplement to Austroads Guide to Road Design Part 1 facilitates the continuing harmonisation of Transport and Main Roads Technical Publications to Austroads guides, while allowing for Queensland specific needs. 

The following are frequently asked questions that have been compiled for practitioners to provide additional context and information.

Can Extended Design Domain (EDD) values be adopted without due consideration of Normal Design Domain (NDD) alternatives?

It depends on the design class:

• Design Class C and D projects: for geometric parameters not assessed (most), the existing geometry is to remain (including EDD values). For assessed parameters, NDD should be considered before EDD.
• Design Class B projects and Design Class A involving modifications to existing roads in brownfield sites: an existing EDD value will suffice unless there is an associated crash history or there is a combination of geometric minima likely to lead to a poor crash outcome.
• Design Class A involving construction of a new road in a Brownfield site: NDD values are the norm. In constrained situations, an EDD value may need to be considered.
• Design Class A involving construction of a new road in a Greenfield site: NDD values are the norm. Only in the most constrained of circumstances would an EDD value be considered to achieve a design outcome to satisfy budgetary constraints while not compromising safety.

Can Design Exception (DE) values be adopted without due consideration of EDD or NDD alternatives?

Again, it depends on the design class:

• Design Class C and D projects: for geometric parameters not assessed (most), the existing geometry is to remain (including DE values). For assessed parameters, NDD / EDD should be considered before adopting a DE.
• Design Class B and Class A involving modifications to existing roads in brownfield sites: an existing DE value should be firstly considered for upgrading to an EDD / NDD value, before justification of the DE value.
• Design Class A involving construction of a new road in a Brownfield site: NDD values are the norm. In constrained situations, an DE value may need to be considered.
• Design Class A involving construction of a new road in a Greenfield site: NDD values are the norm. Only in the most constrained of circumstances would an DE value be considered to achieve a design outcome to satisfy budgetary constraints while not compromising safety.

Does the answer to the previous question change if the Design Exception is a commonly accepted design exception?

No – except the justification of the commonly accepted design exception is already completed.

Will EDD proposals still require detailed reporting with engineering certification?

More extensive justification for geometric minima proposals which may include EDD elements, especially for major projects or those with greater design classes, are still required. Combining geometric minima within proximity, which can include EDD and DE, warrants completing a Design Exception Report as an attachment to a Design Development Report. EDD elements in isolation, require less justification and can be documented to a lesser degree within Design Development Reports.

Who is responsible for the certification and approval of EDD and DE proposals?

In accordance with the Professional Engineers Act 2002, a RPEQ is responsible for certification of all designs produced for the QDTMR to demonstrate compliance and acceptability in terms of technical acceptability.

The Transport and Main Roads Project Manager is responsible for managing a project and ensuring it achieves project objectives, including quality, time, and cost targets agreed with the Project Representative. Role varies by project type and may involve managing the entire project or specific phases / components. It is expected they will approve the Design Development Report which acknowledges the proposal satisfies project scope, objectives and budget for EDD and commonly accepted DEs, considering technical and non-technical risks. They are also required to approve Design Exception Reports, which detail not yet commonly accepted design exceptions and geometric minima proposals, and are to be referenced from or attached to the Design Development Report. There is no requirement for the Transport and Main Roads Project Manager to certify Design Development Reports or Design Exception Reports as this is the responsibility of the Transport and Main Roads or Consultant RPEQ.

All required documentation (including project drawings and the Design Development Report (with associated Design Exception Reports if required) are then to be submitted to the Project Representative before release.

The Project Representative is typically the Regional or District Director but can be delegated to project managers as a dual role and is responsible for approving the project for release on the network. The Project Representative may be asked to optionally review the design for non-technical risks if requested by the Transport and Main Roads Project Manager.

They are ultimately responsible for approving the release of the overall project plan, proposal(s), or Issued For Construction (IFC) design on the network and act as a final checkpoint before the project moves forward to implementation, focusing on the completeness and appropriateness of the design documentation. This is NOT a professional engineering service, but rather acceptance of the process of applying the design on the network.

What is the difference between a commonly accepted DE and a DE that excludes those commonly accepted?

A commonly accepted DE is one that is present or has been integrated into the network at multiple locations. DEs not yet commonly accepted still require justification within Design Exception Reports.

Can EDD or commonly accepted DE proposals be populated within detailed reports?

Although not mandated, they can be included within Design Exception Reports in lieu of inclusion with the main body of Design Development Reports. Unlike geometric minima or DEs not commonly accepted, justification may be to a lesser degree.

As EDD proposals do not require detailed justification why can’t they be classified within NDD?

EDD is based on extensive research that enables designers to adopt reduced values in specific situations. There is still an additional degree of safety risk, hence why the use of EDD is generally limited to Brownfield sites, which prevents inclusion within NDD which is more desirable.

What are the differences between EDD, pre-existing DE, new DE and commonly accepted DE proposals?

EDD proposals are those that comply with the set criteria based on data and research in RPDM. Pe-existing or new DE proposal do not have a precedent and cannot be confidently backed by such data and research. Commonly accepted DEs are for multiple circumstances that must meet the conditions stipulated in the RPDM. They could be considered as potential EDD proposals in future. However, they will require a more detailed assessment beyond the scope of this revision.

Are there reduced liability concerns for RPEQs certifying EDD proposals now that they do not require separate detailed reporting?

Justification for any design, even if not requiring producing a thoroughly detailed Design Exception Report and deemed to be minor in comparison, will still require engineering certification. The RPEQ is expected to detail as much content as necessary to reduce this risk no matter how the proposal is documented.

Can project managers certify and approve design development reports and design exception reports?

Even if the project manager is a RPEQ it is expected that the design RPEQ certifies design proposals, as they operate in separate roles with defined responsibilities. Project managers are obliged to approve reports acknowledging certification by the design RPEQ.

Can Project Representatives approve design development reports?

Yes, they are permitted to however it is not a requirement. It is usually expected that Project Representatives approve designs for inclusion on the network after considering design documentation, such as design development reports, which have independently been approved by the Project Manager.

Why are project managers only permitted to approve non-technical aspects for acceptability?

Project Managers fulfill separate roles than design RPEQs who are to certify designs for suitability in terms of technical content. Project Managers, who represent the client whether they are RPEQs or not, would be expected to have knowledge of network and regional / district risks that the design RPEQ may not be aware of.

Is it a requirement that Engineering and Technology Branch peer review every project with EDD or DE proposals?

Project Managers that have design proposals only involving combining geometric minima or design exceptions (not including those commonly accepted) are to consult Engineering and Technology Branch prior to designers producing Design Exception Reports.

Will QDTMR take responsibility for design proposals that are not compliant or result in litigation once implemented?

In accordance with the Professional Engineers Act 2002, the design RPEQ is to take full responsibility for any design proposal on project, in so far that the project in is accordance with the Departments policies and procedures. The RPEQ does not take responsibility for any adverse safety outcomes unless the design is considered inappropriate in accordance with the bounds and philosophy provided by the Departments policies and procedures.

If the project scope indicates that EDD or DE aspects can be incorporated into designs, do they still require engineering certification?

The scope of works within the project brief, or functional specification, can stipulate permission to include EDD or DE aspects into the project. Should EDD or DE be incorporated the design RPEQ is to certify all design aspects. Permission to use does not preclude RPEQ certification.

Who is responsible for recording commonly accepted DEs?

Individual Districts / Regions can record their own commonly accepted design exceptions. They can also be registered with Engineering and Technology Branch. They will be compiled as DEs that have multiple occurrences throughout the state. They will be updated periodically and can be retrieved if requested.

Can individual regions / districts permit their own commonly accepted DEs that have not been registered with Engineering and Technology into design proposals without question?

Yes. These can also be submitted to Engineering and Technology Branch as a record accessible upon request for the benefit of statewide use.

For a nominated design class, is minimal justification now only required for DE proposals rather than in exceptional circumstances which requires detailed reporting?

The same justification is required depending on whether the DE is commonly accepted or not. Commonly accepted design exceptions already have the justification completed. Complex or pilot projects which may include geometric minima or DEs not commonly accepted will still require detailed reporting.

Will all EDD and DE details still require placement on design drawings and be submitted to Plan Room?

Yes, disclosure of geometric design criteria on drawings will still be required for most proposals as a permanent record. Justification for isolated EDD proposals and commonly accepted DEs are to be included within Design Development Reports, otherwise they are to be included within Design Exception Reports. References are required to design development reports or design exception reports for additional supporting EDD or DE information and justification.

Where can I go for more information?

Please see RPDM Volume 3 Part 1 - Extended Design Domain and Design Exceptions Process Update (2026) for awareness training.

For general enquiries or feedback please get in touch with Road Design Unit at [email protected].