Traffic Impact Assessment: Be Ready for the Future

Introduction

TIA is a study to assess the traffic engineering implications of a proposed development on the road network. As road authorities are responsible for the safe and efficient management of road networks, it enables the road authority to determine whether the road network will be able to handle the traffic generated by the proposed development, especially in the short term. Simultaneously it enables an assessment of the mitigating measures which may be required on the traffic network such as the installation of additional roadway capacity on the existing road network, new road links, modifications to existing intersections, installation of new signalised intersections, pedestrian facilities, upgraded footpaths or bike paths to offset or minimise the impact of the proposed development.

It may also be used to assess whether the proposed parking provision can accommodate the development’s peak parking demands and, if there is any parking overspill, whether this can be adequately accommodated on the surrounding road network without impacting upon the amenity of the area.

TIA Information requirements

Typical input details include:

• Location
• Current use of the site
• Applicant’s (or land owners) name
• Size of existing use and proposed development
• Proposed hours of operation
• Number of employees and visitors (if known)
• Layout plans of the existing site and proposed development
• Current and intended us of immediately adjacent parcels of land
• Planning Scheme map showing how all private and public land is zoned
• Configuration of the immediately surrounding road network

Period of the Study

The period of the study means the hours during which the assessment will be focused, such as:

• Weekday am and pm commuter peak hours
• Weekday am and pm development peak hours
• Daily (24 hour) period

Traffic Counts

Common data collected for input into the TIA include:

• Counting traffic such as cars, trucks, cyclists, pedestrians during the weekday periods (excluding public holidays)
• Data collected in 15 minute intervals
• Counting the number of cars parked in on-site, on- and off-street parking areas in the vicinity of the development site
• Accident history at key road sections in the immediate vicinity of the site

The Need for a TIA

The trigger for requiring a TIA may relate to whether the proposal is classified as a ’major development’ or if the development is considered to have an impact on the safety and operational efficiency of the adjacent roads.

The Outputs

A TIA could include:

• A description of the development in terms of land use size
• A description of the operation characteristics of the existing road network
• Analysis of the operation of the development access points
• Analysis of the existing operation of the immediately adjacent intersections
• An analysis of the trip generation (inbound and outbound movements) during the peak hours
• Assignment of the forecast traffic flows to the development access point and surrounding road network for the peak hours
• Analysis of the future operation of the immediately adjacent intersections
• An assessment of the existing supply and demand of car parking in the immediate vicinity of the development site
• An assessment of the ability of the surrounding parking supply to accommodate any potential parking overspill during the peak time periods

Developer Responsibilities

Once any developer is notified that they are required to prepare a TIA, it is their responsibility to carry out the study. Any mitigating measures which are identified as part of the TIA are usually the responsibility of the developer to fund to minimise the impact of their development upon the surrounding transport network.

Conclusion

TIA typically there are many other aspects associated with TIA including an assessment of other impacts. Although delving deeper into these subjects will extend this blog beyond its scope, each element has a distinct significance.

Speaking to a professional consultant can help you get more insights into traffic engineering and why TIAs are such an important requirement for many developments in Melbourne, Sydney and in other urban and rural area around Australia. If you have any questions or are unsure whether your development requires a TIA, feel free to speak with one of our traffic engineers on 0408 395 729.