Traffic and Transport Assessments – The key points to consider for developments

Traffic and Transport Assessments – The key points to consider for developments

Frequently, the impact of the development on the surrounding traffic network is often overlooked. This oversight is not out of negligence, but we can all take the road network we use every day for granted. It forms part of the fabric of life and therefore we expect it to perform to our needs.

How can we tell if the road network will perform to our needs?

Traffic and Transport Assessments – The key points to consider for developments

In order to assess the impact that a development will have on the existing road network, traffic and transport engineers carry out a Traffic and Transport Assessment (TTA).

The assessment considers:

  • The anticipated traffic generation of the development using industry databases
  • The existing surrounding road network, focusing on key road junctions in the vicinity of the development site
  • The baseline traffic volumes on the surrounding road network obtained by traffic counts
  • Using the baseline information and anticipated development traffic, traffic flow for the junctions under investigation are calculated
  • Using growth rates, the anticipated traffic volumes can be calculated for future years
  • The data in these models will be used in specialist traffic modelling software to assess the key junctions
  • The analysis will also assess the possibility of using more sustainable modes of transport.
So, what does all this data and analysis mean?

The traffic software will provide accurate assessment on how the junctions under investigation will perform once the development has been constructed. The software will also be used to create an insight into how the development will impact on the investigated junctions in the future.

Following on from the analysis, it will be clear if:

  • Junction and road upgrades are required. This may even be required to deal with the baseline traffic volumes
  • The analysis may indicate that an alternative junction type is required to reduce queue times
  • Or hopefully, the analysis will show that the road and junctions are operating well within capacity and the proposed development will have very little impact in terms of traffic
How to know if a TTA is required for a development?

Transport Infrastructure Ireland (TII) has produced a planning and evaluation standard outlining the guidelines to the TTA. The TII document number is PE-PDV-02045 (May 2014). This document outlines when a TTA is required and is dependent on:

  • The type and size of development proposed
  • The location of the proposed development
  • The amount of traffic to be generated by the development and the times of day which the development will generate its peak traffic
  • Whether the development will directly affect a national road
How can ORS help?

ORS has a dedicated traffic and transportation team consisting of leading road safety and transportation consultants. We use the latest industry standard software and technology to explore all possible solutions to give our clients the best experience and end product, all while offering value for money.

The ORS traffic and transport team is available to answer any questions on current or potential projects. Contact us today at or

Block A, Marlinstown
Business Park, Mullingar,
Co.Westmeath, Ireland.
N91 W5NN

Pembr, 127 Baggot Street Lower, Baggotrath Dublin, D02 F634

Eyre Square,
H91 HY51

Office 4, Spencer House,
High Road, Letterkenny,
Co. Donegal,
Ireland. F92 PX8N

Republic of Work,
12 S Mall,
Centre, Cork,
T12 RD43

ORS has satellite offices in Newry and Maynooth.

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