Thurles Traffic Model Report - tipperarycoco.ie

Liberty Square, Thurles Refurbishment Project

Traffic Modelling Report

DRAFT May 2015

Client: Michael Devery Tipperary County Council Civic Offices Nenagh Co. Tipperary

Consulting Engineer: Roughan & O'Donovan Arena House Arena Road Sandyford Dublin 18

ROUGHAN & O'DONOVAN Tipperary County Council Consulting Engineers Traffic Modelling Report

15.136 May 2015 Page i


Traffic Modelling Report Document No: ...................................... 15.136.10 Author: .................................................. Deirdre Neff Checker: ............................................... Eoin Ó Catháin Approver: .............................................. Eoin Ó Catháin

Document No Revision Description Made Checked Approved Date

15.136.10 - DRAFT DN EOC EOC June 2015


15.136 May 2015 Page ii


Traffic Modelling Report

TABLE OF CONTENTS

1. INTRODUCTION ................................................................................................ 1

2. DESCRIPTION OF THE SCHEME ..................................................................... 1

2.1 Existing Road Layout ........................................................................................... 1

2.2 Proposed Scheme ............................................................................................... 2

3. TRAFFIC MODELLING ...................................................................................... 3

3.1 Traffic Count Data ................................................................................................ 3

3.2 Model Description ................................................................................................ 4

4. MODEL CALIBRATION & VALIDATION ........................................................... 5

4.1 Model Calibration ................................................................................................. 5

4.2 Model Validation .................................................................................................. 5

5. RESULTS AND CONCLUSIONS ....................................................................... 7

5.1 Results................................................................................................................. 7

5.2 Conclusions ......................................................................................................... 7 APPENDIX A Traffic Survey Data & Queue Length Observations APPENDIX B Model Calibration and Validation


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1. INTRODUCTION Roughan & O'Donovan (ROD) has been commissioned by Tipperary County Council to carry out a Traffic Modelling exercise on the proposed refurbishment scheme in Liberty Square, Thurles. This report has been prepared with due consideration for the requirements specified in the NRA Project Appraisal Guidelines (PAG) Unit 5.2 Construction of Traffic Models.

2. DESCRIPTION OF THE SCHEME

2.1 Existing Road Layout

Two key National Secondary Routes interact at Liberty Square in Thurles Town. The N62, which links with the M6 motorway at Athlone, the M7 motorway at Roscrea, and the M8 motorway at Horse and Jockey, is the main arterial route through the mid-lands of Ireland; the N75 links the east of Thurles Town to the M8 motorway at Twomileborris. Various other Regional Roads tie into the Town Centre such as the R660 from Cashel and the R498 from Nenagh.

Figure 2.1 Thurles Liberty Square

The interaction of these roads intersect at Liberty Square at a de facto roundabout configuration. Two parking areas are provided in the centre of the roundabout; elsewhere, on-street parallel parking is located on the N75 Liberty Square. A taxi rank is located outside the Tesco Premises. No formal loading facilities are provided within the Town Centre.


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2.2 Proposed Scheme

The proposed refurbishment scheme for Liberty Square incorporates the following changes to the Town Centre:

Removal of all existing on-street parking along the N75 between the N62 and Emmet Street;

Provision of formalised loading and parking bays on the N75 between the N62 and Emmet Street;

Replacement of taxi rank with a parking lay-by;

Deconstruction of 1 no. building to provide an entry only to a proposed new car park from the N75;

Provision of a right turn lane on the N75 into the proposed new car park;

Reduction in carriageway space from two lanes to one lane in each direction on the N75;

Wider footpaths along the N75 between the N62 and Emmet Street; and

Removal of existing controlled crossing and replacement with 4 no. uncontrolled crossing facilities.

Figure 2.2 Extract of Design Proposal by URS Ireland Ltd


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3. TRAFFIC MODELLING

3.1 Traffic Count Data

A manual classified traffic count survey was carried out Thursday April 16th 2015 by Abacus Transportation Surveys at three keys locations - Liberty Square (surved as a roundabout), N62 Slievenamon Road / Thomond Road, and N75 Liberty Square / Emmet Road. The survey was carried out during three hour peaks, at 07:30-10:30 in the AM Peak and 16:30-19:30 in the PM peak.

Figure 3.1 Traffic Survey Locations

Queue lengths were also observed for each arm of the three junctions (not including the circulatory carriageway lanes). The results of the Traffic Survey and Queue Length Observations are provided in Appendix A. On the day the survey was carried out, the N62 Parnell Street was closed in the southbound direction however some local traffic was recorded. Simple diversions were available via the N62 Cuchulain Road between the N62 Parnell Street and the N62 O'Donovan Rossa Street, and via the new Thurles Link Road further north. This traffic that would otherwise have accessed the Square from N62 Parnell Street instead accessed the Square via the N62 O'Donovan Rossa Street c. 30m downstream via a left only one-way street. This will not have had any appreciable impact on the traffic circulation around the Square.


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Significant queuing was observed on the N75 Liberty Square in the westbound direction however this was not solely due to traffic building up at the stop line but rather constant turbulence due to several factors such as double parking, loading, and other parking manoeuvres which reduce the road capacity. Significant queuing was also observed along Emmet Road however this was an issue with significant pedestrian movements at this junction as opposed to gap acceptance.

3.2 Model Description

The implications of the reduced road space on the N75 Liberty Square on the National Roads and the general traffic flow through the town have been modelled using S-Paramics Micro-Simulation software as required by the NRA PAG. An initial model was provided by Tipperary County Council for the entire Thurles area however a new model was subsequently set up to reflect the junctions most affected by the proposed refurbishment. The output comparison between the existing and proposed models will be based on traffic flow through the junctions by assessing road capacity as opposed to queue lengths.

3.3 Outcome of Modelling

A visual assessment of the S-Paramics model indicates that the capacity of the road network will not be reduced with the implementation of the refurbishment proposals. The turbulent impact of parking and loading activities will be greatly diminished by the removal of perpendicular parking and the formalisation of parallel parking and loading facilities. This will have a positive impact on the traffic flow on the N75, which currently relies on a two-lane road width to allow these activities to take place – which in turn causes greater turbulence as a result of weaving. The S-Paramics model indicates that the refurbishment proposals will not create increased queue lengths or delay for motorists compared to the existing situation. The traffic capacity of the gyratory system at the western end of the Square will not be appreciably affected by the proposals.


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4. MODEL CALIBRATION & VALIDATION Calibration and Validation of a model are defined as follows:

Calibration - the estimation of the parameters of a chosen model by fitting observation;

Validation - the assessment of the validity of a calibrated model, either by the qualitative comparison of estimates produced by the model with information not used as a constraint in the model calibration, or by the direct estimation of the accuracy of model estimates.

Calibration and Validation of the model has been carried out and described in the following sections.

4.1 Model Calibration

The calibration criteria outlined in the NRA PAG is as provided in Table 1 below. Table 1 Calibration Criteria

The individual flows from the Traffic Survey and the S-Paramics model are used for calibration. The individual flows are within the thresholds in more than 85% of cases. The GEH Statistic for the individual flows is also less than 5 for more than 85% of cases. This calibration is provided in Appendix B.

4.2 Model Validation

The validation criteria outlined in the NRA PAG is as provided in Table 2 below.


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Table 2 Validation Criteria

The individual flows from the Traffic Survey and the S-Paramics model are used for validation. The individual flows are within the thresholds in more than 85% of cases. The GEH Statistic for the individual flows is also less than 5 for more than 85% of cases. This validation is provided in Appendix B.


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5. RESULTS AND CONCLUSIONS

5.1 Results

The results of both the existing and proposed models are as follows:

The existing model satisfies the requirements of the NRA PAG calibration criteria;

The proposed model satisfies the requirements of the NRA PAG validation criteria;

The refurbishment proposals will not result in an appreciable difference between the existing and proposed capacity of the existing road layout. Some additional benefits to road capacity are anticipated to arise from the rationalisation and formalisation of parking and loading facilities.

5.2 Conclusions

The conclusion drawn from the micro-simulation carried out on both the existing and proposed refurbishment of Liberty Square is as follows:

The reduction of the road carriageway on the N75 Liberty Square to one lane in each direction will not have an appreciable adverse effect on traffic capacity and throughput should be improved by the more rationalised parking and loading arrangements.

ROUGHAN & O'DONOVAN Insert Contracting Authority Name Consulting Engineers Insert Project Title

15.136 June 2015 Appendix A

APPENDIX A TRAFFIC SURVEY DATA & QUEUE LENGTH OBSERVATIONS

ROUGHAN & O'DONOVAN Insert Contracting Authority Name Consulting Engineers Insert Project Title

15.136 June 2015 Appendix B

APPENDIX B

MODEL CALIBRATION AND VALIDATION

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