5.1 Introduction. 5.2 Data Collection

Transcription

1 Chapter 5 Traffic Analysis 5.1 Introduction This chapter of the EIS assesses the traffic impacts of the proposed N5 Westport to Turlough Road Project (the proposed scheme). The proposed scheme will provide an alternative route to the existing N5 which currently runs through a number of urban areas including Castlebar and Westport. 5.2 Data Collection Traffic Surveys A number of traffic surveys were commissioned in late 2012 and early 2013 to provide up-to-date data for development of the traffic model whilst previous data from surveys taken in 2010 were also considered. This data incorporated: Automatic Traffic Counts (ATC) October 2012/ March 2013; Origin- Destination Surveys (OD) March 2013; Manual Classified Counts (MCC) June 2010/ March 2013; and Journey Time Surveys March Traffic flow data from the National Roads Authority (NRA) Traffic Monitoring Unit (TMU) database was also incorporated. The location of all traffic surveys is illustrated in Plates 5.1 to Journey Time Surveys Journey time information was also collected in order to ensure that the travel time on the existing roads was properly reflected within the base models, thereby ensuring that a robust assignment could be undertaken. The journey time and delay surveys were collected along the N5 using the waypoints shown in Plate 5.4 during the morning and evening peak over two weekdays in March The journey time surveys measured journey time and delay. Journey time is defined as the point to point time taken for undertaking a journey, while delay is defined as the time spent stationary while undertaking that journey as a result of traffic congestion or signals Existing Modelling Tools The National Traffic Model (NTM) was developed by the NRA in 2008 and is currently maintained as a central analysis tool for the assessment of the future needs of the network at a strategic level. The modelled network includes all National Primary, Secondary and Regional Roads, plus other local roads of significance. The model is constructed to represent a 2006 Base Year and Future Years of 2025 and Network information is thus available on existing and proposed road links throughout the country. Ref: (07.522) September 2013 Page 5/1

2 Plate 5.1 Traffic Survey Locations Ref: (07.522) September 2013 Page 5/2

3 Plate 5.2 Castlebar Town Centre Traffic Survey Locations Plate 5.3 Westport Town Centre Traffic Survey Locations Ref: (07.522) September 2013 Page 5/3

4 Plate 5.4 Journey Time Surveys Ref: (07.522) September 2013 Page 5/4

5 Roughan & O Donovan - FaberMansell Alliance 5.3 Base Year Traffic Models (2013) Network Development The study area for the traffic model is shown below in Plate 5.5. This area was cordoned from the NTM and refined based on observations of road and junction geometry. Plate 5.5 Modelled Network Matrix Development As part of the model development, the zones used in the NTM for the urban areas of Castlebar and Westport were disaggregated to allow more precise movements in and out of the town centres to be modelled. Larger zones are used in the rural areas. The N5 Local Area Model (LAM) consists of 76 zones, with 64 zones representing demand within the study area (internal zones) and 12 zones feeding demand into the study area (external zones). Uncalibrated trip matrices were firstly constructed for the AM Peak Hour (08:00 09:00) and PM Peak Hour (17:00 18:00). These trip matrices were then calibrated to reflect link flow data and junction turning movement data undertaken in accordance with the criteria as set out in the NRA Project Appraisal Guidelines (PAG) Ref: (07.522) September 2013 Page 5/5

6 Roughan & O Donovan - FaberMansell Alliance Model Category The traffic modelling for the proposed scheme is based on an Assignment Model as defined in PAG Unit 5.2: Construction of Transport Models. The model therefore assigns a fixed demand matrix based on the lowest generalised cost route between defined origin and destination zones. 5.4 Future Year Traffic Models (2018 & 2033) Network Development The future year Do-Minimum network includes the 2013 existing network with only committed infrastructure improvements. For the current model, no committed or planned schemes are relevant, and it is therefore assumed that the existing network, properly maintained will form the Do-Minimum network for the future year. As such no changes to the base year network have been incorporated as part of the Do- Minimum scenario. The future year Do-Something network includes all the assumptions of the Do- Minimum network plus the proposed scheme. The Do-Something network is shown in Plate 5.6. Ref: (07.522) September 2013 Page 5/6

7 Roughan & O Donovan - AECOM Alliance Plate 5.6 Do-Something Network Ref: (07.522) September 2013 Page 5/7

8 Roughan & O Donovan -FaberMaunsell Alliance Traffic Growth The development of the traffic growth forecasts for the future year N5 LAM has been based on the requirements as set out in PAG Unit 5.4: Zone-Based Traffic Forecasting. The guidance sets out separate methodologies for establishing trip end growth for internal and external zones in the Local Area Model (LAM). Traffic models have been developed for the following years: Base Year 2013; Scheme Opening Year 2018; and Scheme Design Year 2033 The PAG specifies that the proposed scheme should be assessed using three future traffic growth scenarios, namely low, medium and high. The overall growth in vehicular trips between the Base and the Opening Year and the Base and Design Year is outlined in Tables 5.1 and 5.2 respectively. Table 5.1 Overall Traffic Growth in Study Area ( ) NRA Growth Scenario Heavy Commercial Light Vehicles (LV) Vehicles (HCV) AM Peak PM Peak AM Peak PM Peak Low 5.1% 5.0% 3.1% 3.1% Medium 6.3% 6.2% 4.0% 5.1% High 11.3% 11.2% 8.2% 9.9% Table 5.2 Overall Traffic Growth in Study Area ( ) NRA Growth Scenario Heavy Commercial Light Vehicles (LV) Vehicles (HCV) AM Peak PM Peak AM Peak PM Peak Low 20.5% 20.2% 9.9% 10.7% Medium 22.5% 22.0% 12.5% 14.2% High 41.0% 40.4% 25.3% 26.7% Future year models have been developed for all three growth scenarios. As the medium growth rate represents a central forecast of future growth only the NRA medium growth results are presented throughout the remainder of this chapter of the EIS Estimation of Annual Average Daily Traffic (AADT) The Annual Average Daily Traffic (AADT) on the proposed scheme and parallel routes was estimated by applying conversion rates to modelled AM and PM peak hour traffic flows. A relationship was developed based on regression analysis of 2 permanent NRA counters and a number of long term ATC counters in the study area. The formula developed is as follows: AADT = (6.4 * AM Flow) + (5.2* PM Flow) Ref: (07.522) September 2013 Page 5/8

9 Roughan & O Donovan -FaberMaunsell Alliance 5.5 Scheme Impacts The proposed scheme will lead to a number of notable impacts on traffic flows as road users re-route to take advantage of the new infrastructure. The key impacts are outlined here for the Opening Year (2018) and Design Year (2033). See Figure 5.1 in Volume Opening Year (2018) Forecast traffic volumes for the medium growth scenario in the Opening Year (2018) are shown in Table 5.3. The locations for traffic flow data are presented graphically in Plate 5.7. Traffic within the study area is forecast to grow by a total of 6.2% between 2013 and Table 5.3 Link Flow Summary for 2018 Opening Year (Medium Growth) No. Link 2013 Base 2018 Do-Min 2018 Do-Some 1 N5 East of Westport N5 Westport Road (Existing) N5 Westport Road (approaching Castlebar) N5 Humbert Way (R310 N60 Junction) N5 Lawn Road (N60 R373 Junction) N5 Turlough Road (East of Castlebar) N84 South of Proposed N N84 North of Proposed N N60 North of Proposed N N60 South of Proposed N N5 West of Turlough N58 Straide Road N5 West of Bohola N58 South of Foxford R321 Kiltamagh Road Westport Link Road (Proposed) Westport Link Road (Proposed) N5 Westport Road (Proposed) Proposed N5 (N5 to N84) Proposed N5 (N84 to N60) Proposed N5 (N60 to N5) In the Do-Minimum scenario, traffic on the N5 between Westport and Castlebar is forecast to grow from AADT in 2013 to AADT in This represents an overall increase of 5.3% on the N5 over that period. East of Castlebar, traffic is forecast to grow by 5% from AADT in 2013 to AADT in the 2018 Do- Minimum scenario. Ref: (07.522) September 2013 Page 5/9

10 Roughan & O Donovan -FaberMaunsell Alliance The traffic forecasts in Table 5.3 highlights a number of significant impacts of the proposed scheme as follows: A significant reduction in traffic using the existing N5 Westport Road between Castlebar and Westport. This decrease is close to 80%, and is a result of traffic transferring onto the proposed N5; A notable reduction on the existing N5 through Castlebar between the Westport Road and the N5/R373 Moneen Roundabout, where a decrease of between 25-35% is forecast. The net effect is the re-routing of up to 6800 vehicles onto the proposed N5. This offers significant relief to the existing N5 through Castlebar; and An increase of approximately 9% on the N5 East of Castlebar and a 11.6% increase on the N58 South of Straide as a result of the capture of traffic travelling between Castlebar and Foxford/Ballina via the R310 Pontoon Road, with a subsequent decrease on the R310 North of Castlebar of 33%. This growth in traffic and subsequent decrease in average speeds along some regional roads leads to additional re-routing effects. These include: Traffic between Newport and the east of Castlebar which previously used the R311, now transfers onto the new N5 Westport Road (200 AADT); and Traffic between Kiltamagh and west of Castlebar which previously used the R324/N60, now transfers onto the N5 Turlough Road. This results in an 18% decrease on the R324 with a subsequent increase of 2% on the N5 west of Bohola and 9% on the R321 Kiltamagh Road. Plate 5.5 indicates the location of the regional roads discussed above. In summary, the key effects are a transfer of traffic from the existing N5 onto the proposed scheme between the Knockranny junction and the Castlebar East junction. There are also more limited impacts on the N58 and N5 East of Castlebar due to the reassignment of the north-south movement between the Castlebar area and Foxford/Ballina area as well as less significant re-routing on some regional roads. Ref: (07.522) September 2013 Page 5/10

11 Plate 5.7 AADT Locations Ref: (07.522) September 2013 Page 5/11

12 5.5.2 Design Year (2033) Forecast traffic flows for the 2033 Design Year are set out in Table 5.4, again for the medium growth scenario. Overall traffic is forecast to increase within the study area to the order of 22% between 2013 and Table 5.4 Link Flow Summary for 2033 Design Year (Medium Growth) No. Link 2013 Base 2033 Do-Min 2033 Do-Some 1 N5 East of Westport N5 Westport Road (Existing) N5 Westport Road (approaching Castlebar) N5 Humbert Way (R310 N60 Junction) N5 Lawn Road (N60 R373 Junction) N5 Turlough Road (East of Castlebar) N84 South of Proposed N N84 North of Proposed N N60 North of Proposed N N60 South of Proposed N N5 West of Turlough N58 Straide Road N5 West of Bohola N58 South of Foxford R321 Kiltamagh Road Westport Link Road (Proposed) Westport Link Road (Proposed) N5 Westport Road (Proposed) Proposed N5 (N5 to N84) Proposed N5 (N84 to N60) Proposed N5 (N60 to N5) Do Minimum The traffic forecasts indicate that a 20% increase in traffic volumes along the N5 corridor will occur over the period to 2033, with traffic on the N5 between Westport and Castlebar forecast to grow from AADT in 2013 up to AADT in The forecast AADT on the N5 east of Castlebar in the 2033 Do-Minimum scenario is AADT, this represents a 20% growth over the period 2013 to Do Something The data shows a similar pattern of impacts as reported for The results demonstrate a decrease of close to 80% along the existing N5 Westport Road, and a reduction in flow on the N5 through Castlebar of between 25-35% is forecast. The change in traffic flow on some regional roads is also similar to the pattern reported for The increased growth and subsequent decreased average Ref: (07.522) September 2013 Page 5/12

13 speeds on the R310 North of Castlebar result in some additional re-routing effects, with traffic levels dropping by a further 12% and subsequently increasing by another 10% along the N58. The proposed route is therefore successful in attracting significant volumes of trips from the existing N5, as well as from a number of less attractive regional routes. The result is a significant decrease in traffic on the alternative routes Safety Impacts As outlined in previous sections the opening of the proposed scheme will lead to the re-routing of traffic from the existing road network onto the proposed scheme, with some AADT using the proposed scheme between Westport and Castlebar in The proposed scheme will be of a higher safety standard and will therefore contribute to a network wide reduction in accidents. This is reflected in the economic assessment (Phase 3-Design COBA, medium growth scenario) which forecasts a 10% reduction in the number of accidents over the 30 year appraisal period. This equates to 429 accidents, categorised as follows:- 35 Fatalities (an average of 1.2 fatalities each year) 121 Serious injuries (an average of 4 serious injuries each year) 1229 Slight injuries (an average of 41 slight injuries each year) Journey Time Benefits The proposed scheme leads to reduced journey times along the entire N5 corridor between Westport and Turlough. The increase in road capacity that the proposed scheme delivers and proper road design lead to higher average speeds along the N5 corridor and journey time benefits for both long and short distance trips. The proposed scheme also benefits local traffic, particularly in the urban areas of Castlebar and Westport, as through traffic transfers to the proposed scheme thereby reducing congestion and delays for local traffic within these urban areas. When compared to the 2033 Do-Minimum scenario the proposed scheme reduces the total daily delay in the study area by approximately 1115hrs or 47 days as well improving average speed across the network. Ref: (07.522) September 2013 Page 5/13