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Regional Model System Overview

Why was the RMS Developed?

It was recognized that the NTA needed a completely new regional modelling system after an examination of the NTA’s modelling needs and the current availability of regional models. The five regional models evolved from the former modelling structure that consisted of four models developed from the main centres of population settlement in Ireland. These models were entitled:

  • the Greater Dublin Area (GDA) Model;
  • the Cork Area Strategic Planning (CASP) Model;
  • the Mid-West Area Strategic Planning (MWASP) Model (Limerick City) and;
  • the Galway Transport Model (GTM).

The development of the RMS followed a detailed scoping phase informed by NTA and wider stakeholder requirements. The rigorous consultation phase ensured a comprehensive understanding of available data sources and international best practice in regional transport model development.

Further information on the development of the regional models can be found in the following scoping documentation:

Scoping

The regional model scoping approach has been tailored to meet NTA needs, data requirements and availability, typical uses and case studies, and highlighting applicability in the Irish regional city context. There were seven main steps involved in the regional model scoping process as follows:

Step 1: Workshops held with the NTA modelling and Integrated Planning teams;

Step 2: Expert group discussions between Consultants;

Step 3: A review of the NTA’s transport modelling needs (RMS Scope 1);

Step 4: A review of the current Greater Dublin Area Model, as a potential starting point for the various regional models (RMS Scope 2);

Step 5: A review of Best Practice for developing regional transport models (RMS Scope 3);

Step 6: A review of available data and any remaining data gaps which need to be addressed within the model scoping process (RMS Scope 4); and

Step 7: The production of this Regional Modelling Scoping Report.

Specification

During the specification stage of the model development, the structure of the model was defined more precisely. Building on the scoping stage, the exact functions used within the model were selected that will allow the model to be used for the broadest possible range of uses, based on the client objectives, likely uses and analysis of the data. Key decisions regarding model segmentation, choice model hierarchy and the format of inputs and outputs are agreed at this stage.

There are five main specification reports, namely;

RMS Specification Report 1 Full Demand Model

RMS Specification Report 2 Road Model

RMS Specification Report 3 Public Transport Model

RMS Specification Report 4 Active Modes Model

RMS Specification Report 5 Zone System Development

National Demand Forecasting Model

The National Demand Forecasting Model (NDFM) includes the set of models & tools that are used to derive levels of national levels of trip making from planning data, for input into each of the regional models. The NDFM outputs levels of trip making at the smallest available spatial aggregation, the Census Small Area (CSA) of which there are more than 18,000 across the country.

Appraisal tools

The Appraisal Tools are an integrated suite of tools for the assessment of social, environmental and economic impacts of transport schemes.

Assigment modules

The Road, Public Transport, and Active Modes assignment modules receive the trip matrices produced by the Full Demand Model (FDM) and assign them in their respective transport networks to determine route choice and the generalised cost for origin and destination pairs. 

The Road Model assigns FDM outputs (passenger cars) to the road network and includes capacity constraint, traffic signal delay and the impact of congestion.  See report RM ERM Road Model Report.

The Public Transport Model assigns FDM outputs (person trips) to the PT network and includes the impact of capacity restraint, such as crowding on PT vehicles, on people’s perceived cost of travel.  The model includes public transport networks and services for all PT sub-modes that operate within the modelled area. See the RMS Specification Report 3 Public Transport Model for further informationn.

Secondary analysis

The secondary analysis application can be used to extract and summarise model results from each of the regional models.

What is the Regional Model Used For?

  • Strategic – Assessment of Transport Strategies and Policies, Traffic Management Plans, Travel Demand Management (TDM).
  • Highway – New Roads, Bypass Schemes, Upgrade Schemes
  • Land Use – Appraisal of impacts of Local Area Plans, Development Plans, Policy Assessment.
  • Public Transport and Active Mode Transport: Walking and Cycling Strategies, Integrated Transport, Delivering Public Transport Services.
  • Forecasting: Dart Underground Business Case, Strategic Development Zones (SDZ) e.g. Cherrywood, Clonburris, M50 Demand Modelling

Model Application

Local Transport Scheme Appraisals

“How will the local transport network respond to the proposed traffic management proposals?”

Extract model Flows from the RMS for testing in local junction models e.g. VISSIM or Linsig

Transport Assessments

“What impact will the scheme have on the local transport network?”

Flow Difference plots on the local network – With and Without Development Scenario

 

Galway Transport Strategy

“Would an orbital bus service running along the N6 perform better than a bus service running through the city centre?”

 

Forecasting:

  • Dart Underground Business Case
  • SDZs – Cherrywood, Clonburris.
  • M50 Demand Management Modelling