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Regional Modelling System Overview

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.

Regional Models

There are 5 regions: East Region, West Region, South West Region, South West Region, and Mid-West Region. The five regional models are based on a single coded Cube Voyager structure, which can be applied to any of the five regional areas solely by changing the network and zonal inputs, and calibrating to local data.

Appraisal Modules

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

RMS Structure

In addition to the components described above, the RMS also uses Assignment Models and Secondary Analysis Tools.

Assignment Models

The Road, Public Transport, and Active Modes assignment models receive the trip matrices produced by the 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 ERM Road Model Development 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.

Secondary Analysis

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

 

RMS Dimensions

Modelled Years

  • A 2012 base year (to coincide with Census/POWSCAR and National Household data sets); and
  • Forecasting for any year for which land use (planning data) and infrastructure provision assumptions can be provided. Normally these are prepared for 5-year increments from the base year model (e.g., 2017, 2022, 2027 and so on) to support short, medium and long term horizon planning and appraisal.

Modes of Travel

  • Private Vehicles – Cars (distinguishing between car driver and car passenger);
  • Public Transport Modes: Bus, Rail, Luas, Metro;
  • Park and Ride (including Park and Walk) to/from designated locations;
  • Active Modes (Walking and Cycling);
  • Taxis; and
  • Light Goods Vehicles and other Goods Vehicles in the Road Model.

Time Periods

  • The full day is modelled, and is broken down into 5 time periods as follows:
  • AM Peak period covering the period between 07:00 – 10:00;
  • Morning Inter-Peak covering the period between10:00 – 13:00;
  • Afternoon Inter-Peak covering the period between13:00 – 16:00;
  • PM Peak period covering the period between 16:00 – 19:00; and
  • Off-Peak covering the period between19.00 – 07.00.

In the assignment of trips to the transport networks, a representative single hour is extracted to represent each time period.

 

Journey Purpose and other Demand Segmentations

The datasets determine the demand segmentation possible, i.e. 2011 POWSCAR and the 2012 National Household Travel Survey (NHTS) (described below in Section 2.4.1).

The proportional number of trips by demand segment must be reasonably large to warrant being treated separately as a distinct segment.  Segments that represent very small proportions of overall travel demand are combined.

The model considers different levels of segmentation at different stages of the modelling process, with only the relevant segmentation retained at each step.  Model responses to changes in populations, jobs, etc. are generally improved when the fundamental information—travel demand—is segmented.

 

RMS Development Data Sources

Demand Model

  • Place of Work, School or College – Census of Anonymised Records (POWSCAR, CENSUS 2011)
  • National Household Survey (2012 NHTS).

Road Model

The data used to build the RDAM network, to prepare demand matrices, derive parameter values and provide observed calibration and validation data include:

  • Dublin City Council SCATS Database – traffic volumes and observed signal data;
  • HERE (formerly NavTeq) GIS Database;
  • Census POWSCAR data; and
  • National Household Travel Survey (NHTS)

Public Transport Model

  • NTA Journey Planner – this includes a range of data on walk and cycle network characteristics;
  • Footpath matrix;
  • Cycle Lanes;
  • Bus Lanes; and
  • Pedestrian Crossings.
  • NTA Journey Planner – General Transit Feed Specification (GTFS);
  • Bus Public Timetables
  • Census POWSCAR data;
  • National Household Travel Survey (NHTS);
  • Airport Travel Survey;
  • Automatic Vehicle Location and Control (AVLC) and Real Time
  • Passenger Information (RTPI);
  • Rail/Luas Census passenger counts from various years;
  • Bus Cordon Counts – from 2011, 2012 and 2014;
  • Rail, Luas and Bus ticket sales data; and
  • Leap Card ticket sales data.

RMS Zoning System

The standard geographical units available for zone system development are provided by the Census at the Enumeration Areas or Census Small Areas (CSA) levels. The model zoning systems are based directly on these boundary systems.

Special ‘point’ zones, which have no associated boundary, are also used in the modelling to represent airports, ports, or any other location with unique trip making characteristics.

The criteria used for developing zone boundaries in the regional modelling system include:

  • Population, Employment and Education – zone population, number of jobs and persons in education not to exceed certain maxima;
  • Activity Levels – zone activity levels are mostly kept within a defined range to avoid very low or very high levels of trips;
  • Intra-zonal Trips – a limit was applied to the proportion of intra-zonal trips to avoid an underestimation of trips on the network;
  • Land Use – zones were created with homogeneous land use and socio-economic characteristics where possible;
  • Zone Size/Shape – zones were defined to be not too large or irregular in shape, which helps avoid issues with inaccurate representation of route choice;
  • Political Geography – it is possible to aggregate all zones to DED level i.e. zone boundaries do not intersect ED boundaries; and
  • Special Generators/Attractors – large generators/attractors of traffic such as Airports, Hospitals, shopping centres etc. are allocated to separate zones.

ERM

  • The ERM has 1849 Zones and a number of special zones including
    • Dublin Airport
    • Dublin Port
    • Dun Laoghaire Port
  • For more information please see the ERM Zone System Development Report: (Please note the appendices for this report are available on request.)

ERM Zone System Development Report.

 

SERM

  • The SERM has 571 Zones and in the SERM, one special zone is considered:
    • Rosslare Port.
  • Please see the SERM Zone System Development Report for more information.

SERM Zone System Development Report

 

MWRM

  • The MWRM has 454 Zones.
  • In the MWRM, two special zones are considered:
    • Shannon Airport; and
    • Shannon Foynes Port.
  • Please see the MWRM Zone System Development Report for more information.

MWRM Zone System Development Report

 

WRM

  • The WRM has 454 Zones
  • In the MWRM, two special zones are considered:
    • Shannon Airport; and
    • Shannon Foynes Port.
  • Please see the WRM Zone System Development Report for more information.

WRM Zone System Development Report

 

SWRM

  • The SWRM has 792 Zones.
  • In the SWRM, four special zones are considered:
    • Cork airport;
    • Port of Cork – City Quays;
    • Port of Cork – Ringaskiddy; and
    • Port of Cork – Tivoli.
  • Please see the SWRM Zone System Development Report for more information.

SWRM Zone System Development Report