St Austell to A30 Link

Economic Assessment ReportEconomic Assessment Report
Project number: 60571547
Project reference: 0128 Project number: 60571547
Prepared for: CORMAC Solutions
Alex Bertram Graduate Consultant
v0.1 20/05/2019 First Draft
v0.2 05/09/2019 Second Draft to Include Cost Updates 25/09/19 Thea Wattam
Associate Director
Associate Director
v0.4 13/08/2020 Addition of OBR Sensitivity Test Results (Section 7.7)
13/08/2020 Maurice Houkes
aecom.com
© 2019 AECOM Limited. All Rights Reserved.
This document has been prepared by AECOM Limited (“AECOM”) for sole use of our client (the
“Client”) in accordance with generally accepted consultancy principles, the budget for fees and the
terms of reference agreed between AECOM and the Client. Any information provided by third parties
and referred to herein has not been checked or verified by AECOM, unless otherwise expressly stated
in the document. No third party may rely upon this document without the prior and express written
agreement of AECOM.
3.1 Transport Model .................................................................................................................... 9
3.2 Forecasting ......................................................................................................................... 13
4.1 Economic Appraisal............................................................................................................. 14
4.4 Collision Appraisal ............................................................................................................... 19
5.1 Scheme Costs and Profile ................................................................................................... 21
5.2 Risk and Optimism Bias ...................................................................................................... 21
6. Estimation of Benefits ............................................................................ 22
6.1 Travel Time Benefits and Vehicle Operating Costs............................................................... 22
Overview............................................................................................................................. 22
7. Economic Assessment Results ............................................................. 24
7.1 Travel Time Benefits and Vehicle Operating Costs............................................................... 24
Profile of Benefits over 60 Year Appraisal Period ................................................................. 24
Benefits by Travel Time Saving ........................................................................................... 25
High and Low Growth Scenario Results .............................................................................. 25
7.2 Monetised Environmental Assessment Results .................................................................... 25
7.3 Reliability ............................................................................................................................ 26
7.5 Public Accounts................................................................................................................... 27
7.7 OBR and Fleet Forecast Sensitivity Test Results ................................................................. 28
8. Conclusion ............................................................................................. 31
Appendix A1: Transport Economic Efficiency ................................................................................... 32
Low Growth ..................................................................................................................................... 32
High Growth .................................................................................................................................... 33
Low Growth ..................................................................................................................................... 34
High Growth .................................................................................................................................... 34
AECOM
Figures
Figure 2-1: Proposed Scheme Overview ............................................................................................ 8 Figure 3-1: Area of Detailed Study ..................................................................................................... 9 Figure 3-2: Zone Plan (Detailed Study Area) .................................................................................... 10 Figure 3-3: Zone Plan (Cornwall) ..................................................................................................... 10 Figure 3-4: Zone Plan (Rest of Modelled Area).................................................................................. 11 Figure 3-5: Cornwall Network ........................................................................................................... 12 Figure 3-6: South UK Network ......................................................................................................... 12 Figure 4-1: Location of Traffic Count Sites Used in Annualisation Factor Calculations....................... 15 Figure 4-2: Weekday Traffic Flow Profile .......................................................................................... 15 Figure 4-3: Weekend Traffic Flow Profile .......................................................................................... 16 Figure 4-4: Zone to Sector System, United Kingdom Extent ............................................................. 18 Figure 4-5: Zone to Sector System, Cornwall Extent ........................................................................ 18 Figure 4-6: COBALT Study Area ...................................................................................................... 19 Figure 7-1: Transport Benefits by Year ............................................................................................. 24
Tables
Table 3-1: Modelled Time Period Classification .................................................................................. 9 Table 4-1: Modelled Hour to Peak Period Factors ............................................................................ 16 Table 4-2: Annualisation Factors ...................................................................................................... 16 Table 4-3: Annual Average Daily Traffic Factors ............................................................................... 19 Table 4-4: Accident Costs and Benefits – 2010 Prices ...................................................................... 20 Table 5-1: Scheme Costs ................................................................................................................. 21 Table 5-2: Scheme Cost Profile ........................................................................................................ 21 Table 6-1: TUBA User Classes ......................................................................................................... 22 Table 7-1: Transport Benefits by Trip Purpose .................................................................................. 24 Table 7-2: Total Benefits by Travel Time Saving ............................................................................... 25 Table 7-3: Low Growth Transport Benefits by Trip Purpose .............................................................. 25 Table 7-4: High Growth Transport Benefits by Trip Purpose .............................................................. 25 Table 7-5: Outline Business Case Journey Time Reliability Assessment Results .............................. 26 Table 7-6: Economic Efficiency of the Transport System Results, Core Growth Scenario .................. 26 Table 7-7: Public Accounts Results, Core Growth Scenario .............................................................. 27 Table 7-8: Analysis of Monetised Costs and Benefits, Core Growth Scenario ................................... 28 Table 7-9: Economic Efficiency of the Transport System OBR Sensitivity Test Results ...................... 29 Table 7-10: Analysis of Monetised Costs and Benefits, OBR Sensitivity Test .................................... 30
St Austell to A30 Link
AECOM 6
1. Executive Summary The existing route between St Austell and the A30 is of a variable standard, passing through
a number of villages, with congestion and delays leading to poor journey time reliability. The
new route is needed to help meet Cornwall Council’s objectives of relieving traffic issues
along the current route and unlocking economic potential within St Austell and the
surrounding area.
Cornwall Council and local stakeholders hold an aspiration to create an improved strategic
link between St Austell and the A30. St Austell is Cornwall’s largest town and is not currently
served by a high-quality road link to the A30. The proposed scheme is a new high-quality,
single carriageway route linking St Austell to the A30 and to divert traffic (including Heavy
Goods Vehicles) away from settlements along the existing route(s).
Cornwall Council’s overarching aims for the scheme are to:
• Reduce journey times and improve journey reliability between Newquay, the A30 and St
Austell;
• Create a better link between two of Cornwall’s largest towns (St Austell and Newquay),
the airport and Aerohub Enterprise Zone;
• Make access to Cornwall’s new, large employment sites easier, therefore supporting
the expanding employment sites Victoria Business Park, Indian Queens Industrial
Estate and the Aerohub Enterprise Zone;
• Improve the competitiveness of St Austell as a location to do business via new
employment space or interest in land that can be developed into employment space;
• Support housing growth, including the delivery West Carclaze Garden Village
ecocommunity, which is expected to create 1,500 new homes and 500 jobs; and
• Support the regeneration of Roche, Bugle and St Dennis by addressing traffic related
issues within the villages and creating better opportunities for businesses.
AECOM have developed forecast year models, for assessment years of 2022 and 2037, to
represent the traffic patterns that would be expected to occur with the addition of the
proposed scheme. Further details on the models utilised in this appraisal can be found in
AECOM’s Traffic Forecasting Report (dated September 2019).
This economic appraisal has utilised the most recent version of the Department for
Transport’s (DfT) Transport User Benefits Appraisal (TUBA) version 1.9.13 (July 2019) and
Cost and Benefits to Accidents – Light Touch (COBALT) software version 2013.02 and
COBALT parameters file version 2018.1. The TUBA appraisal includes monetisation of
travel time benefits, vehicle operating costs, and greenhouse gases. The COBALT
assessment provided a monetised appraisal of potential collision changes resulting from the
scheme. In addition, local air quality and noise impacts have also been assessed in line with
current DfT Transport Analysis Guidance (TAG) and Design Manual for Roads and Bridges
guidance.
The assessment presented in this report shows that the scheme offers Medium value for
money with an initial unadjusted benefit to cost ratio of 1.61.
2. Study Overview
2.1 Background Cornwall Council and local stakeholders have an aspiration to create an improved strategic
link between St Austell and the A30. Although St Austell is Cornwall’s largest town, it is not
currently served by a high-quality road link to the A30. The current route is the A391, which
is a variable standard single carriageway route passing through a number of settlements
between St Austell and the A30.
Given its status as the largest town in Cornwall, St Austell is a major attractor of trip origins
and destinations within mid-Cornwall, with heavy industry within the China Clay Area
attracting a high number of Heavy Goods Vehicle (HGV) trips. The low standard of the
current route connections to the A30 result in congestion, delays and traffic safety issues
within affected areas. The route requires improvement to meet Cornwall Council’s objectives
of improving journey reliability, safety and raising economic competitiveness. The current
poor connectivity is seen as the major block to the economic growth of the St Austell area.
The scheme is inherently expected to impact the travel arrangements within St Austell,
settlements along the current route, and to the wider transport network within Cornwall.
Travel patterns would be anticipated to be affected because of route performance
improvements, attracting traffic from other routes. The traffic model has been designed to
forecast the potential impact of these travel patterns across a wide area.
2.2 Scheme Objectives The overarching aim of the scheme is to provide a higher quality link between St Austell and
the A30, and to divert traffic (including HGVs) away from the towns and villages along the
existing routes.
The scheme objectives are aligned with the key policies identified within Cornwall Council’s
regional transport policies, and the Cornwall and Isles of Scilly Strategic Economic Plan
(Vision 2030).
The Council’s objectives for the mid-Cornwall area are:
• Create a better link between two of Cornwall’s largest towns – St Austell and Newquay,
the airport and Aerohub Enterprise Zone;
• Make it easier to access Cornwall’s new, large employment sites and support the
expanding employment sites Victoria Business Park, Indian Queens Industrial Estate
and the Aerohub Enterprise Zone;
• Improve competitiveness of St Austell as a location to do business via new employment
space or interest in land that can be developed into employment space;
• Support housing growth, including the delivery West Carclaze Garden Village
ecocommunity (with the creation 1,500 new homes and 500 jobs); and
• Support the regeneration of Roche, Bugle and St Dennis by addressing traffic related
issues within the villages and creating better opportunities for businesses.
To help achieve these overarching aims, the scheme’s transport-specific objectives are to:
• Reduce journey times and improve journey reliability between St Austell and A30;
• Reduce the impact of traffic congestion on local communities and businesses; and
• Improve the safety of road users, pedestrians and cyclists.
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2.3 Assessment Option A detailed review of the proposed scheme can be found in the Traffic Forecasting Report
Section 6.3, but it broadly follows the ‘Roche Option’ assessed in the Outline Business
Case. The highway has been designed to accommodate vehicles travelling at 60mph and
will replace the B3274 from Stenalees to Trezaise to form a bypass around Roche, linking to
the old A30 west of Victoria (Figure 2-1).
Figure 2-1: Proposed Scheme Overview
In general, the St Austell to A30 Link Road will be single carriageway, with climber lanes
provided at key locations as required. Four new roundabouts will be constructed at
Stenalees, Trezaise, Harmony Road and at the old A30 (C0120).
2.4 Report Structure This TFR sets out information relating to the development of the forecast scenarios and is
structured as follows:
• Chapter 4: Overview of Economic Assessment;
• Chapter 5: Estimation of Costs;
• Chapter 6: Estimation of Benefits;
• Chapter 7: Economic Assessment Results;
• Chapter 8: Summary and Conclusions.
Overview
This chapter provides an overview of the Base Year model. The Local Model Validation
Report (March 2017) details the base model that has been developed by the consultants
PTV to inform the appraisal of the scheme.
The Base Year model formed the basis for the forecast models detailed in this report.
Forecast models have been built for 2022 (the proposed opening year of the scheme) and
2037 (future case fifteen years from the opening year). The forecast models detailed in this
report have been built in compliance with Department for Transport TAG Unit M4
‘Forecasting and Uncertainty’ (May 2018).
Model Time Periods and Network Structure
Neutral month peak and inter-peak time periods have been modelled to fully understand the
operation and economic benefits of the proposed scheme. The modelled time periods are
shown in Table 3-1.
Time Period Modelled Period
Neutral Month Inter Peak Average hour 10:00 – 16:00
Neutral Month PM Peak 17:00 – 18:00
The main study area covers St Austell and includes the towns of Roche and Bugle to the
north, Lostwithiel and Fowey to the east, Mevagissey to the south, and St Stephens and St
Dennis to the west. The extent of the detailed study area is illustrated in Figure 3-1 and
Figure 3-2.
Figure 3-2: Zone Plan (Detailed Study Area)
The remainder of Cornwall has been modelled in varying levels of detail (Figure 3-3). This
area is not as detailed as the main study area but allows for the control of traffic routes into
Cornwall. The wider model area includes the rest of the UK (Figure 3-4). Outside of Devon
and Cornwall the zones become much larger.
Figure 3-3: Zone Plan (Cornwall)
Figure 3-4: Zone Plan (Rest of Modelled Area)
The simulation network (Figure 3-5 and Figure 3-6) is formed of the following sections:
• Cornwall (all roads);
• Major and intermediate routes in Devon, with slightly more detail in Plymouth and
Exeter; and
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3.2 Forecasting The Base Year traffic model was used as the basis of future year traffic forecasts for the
opening year (2022) and design year (2037). Future year models were produced for core,
low and high growth scenarios.
A good level of convergence has been achieved for nearly all modelled scenarios, time
periods and years. The forecast assignments can therefore be considered robust for the
purposes of the economic assessment.
The future year traffic forecasts produced from the forecasting procedures outlined in
AECOM’s Traffic Forecasting Report (dated September 2019) have been utilised in this
assessment.
4. Overview of Economic Assessment
4.1 Economic Appraisal The economic appraisal has utilised the most recent version of the Department for
Transport’s Transport User Benefits Appraisal (TUBA) version 1.9.13 (July 2019) and Cost
and Benefits to Accidents – Light Touch (COBALT) software version 2013.02 and COBALT
parameters file version 2018.1. The TUBA appraisal includes monetisation of travel time
benefits, vehicle operating costs, and greenhouse gases. The COBALT assessment
provided a monetised appraisal of potential collision changes resulting from the scheme.
This section provides a more detailed overview of the appraisal methodology.
4.2 Annualisation Factors Economic appraisal requires a consideration of the benefits to all road users, many of which
will not be travelling at a time represented by the transport model. Benefits per vehicle vary
throughout the day and year to the extent that traffic levels impact on the benefit per vehicle.
The calculation of user benefits requires the calculation of annualisation factors to quantify
the way in which the scheme might affect those travelling during weekdays outside of the
modelled hours or on weekends and public holidays.
The Inter Peak (IP) has been used to reflect the off-peak period, weekends and public
holidays. Periods of low flow, when congestion would not be expected, have been excluded.
The IP was considered to be representative based on the assumption that the traffic levels
during this period provide an appropriate representation of traffic conditions and journey
times during off-peak and holiday periods.
The annualisation factors have been calculated using Automated Traffic Count (ATC) data
from the ten site locations shown in Figure 4-1. Data was used from two weeks in June 2016
(13th to 27th) to calculate the annualisation factors using the guidance set out in TAG Unit
A1.31 and in accordance with discussions with the Department for Transport (DfT)2.
1 User and Provider Impacts (March 2017) 2 St Austell A30 Link Road – DfT Review Meeting Minutes (dated 11th April 2019)
AECOM 15
Figure 4-1: Location of Traffic Count Sites Used in Annualisation Factor Calculations
Based upon the traffic profiles shown in Figure 4-2 and Figure 4-3, separate factors were
calculated for the three modelled time periods on the assumption that each modelled period
will represent the following days and times:
• AM Peak: weekdays between 0745 and 0900;
• Inter Peak: weekdays between 0700 to 0745, 0900 to 1600, and 1800 to 1900; off-
peak (0500 to 0700 and 1900 to 0000) weekends and public holidays; and
• PM Peak: weekdays between 1600 and 1800.
Figure 4-2: Weekday Traffic Flow Profile
Figure 4-3: Weekend Traffic Flow Profile
The method outlined above resulted in the modelled hour to peak period factors presented
in Table 4-1.
Monday to Thursday Friday Saturday Sunday
AM Peak 1.24 AM Peak 1.23
13.33 10.68 Inter Peak 8.47 Inter Peak 8.42
PM Peak 1.95 PM Peak 2.00
Off Peak 2.27 Off Peak 2.24
The following breakdown of days within a year has been adopted in the calculation of
annualisation factors:
• 52 weekends (104 days); and
• 8 bank holidays.
A summary of the annualisation factors for the modelled time periods are shown in Table 4-
2.
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4.3 Travel Time Benefits and Vehicle Operating Costs Travel time benefits and the impact on vehicle operating costs for the proposed scheme
have been assessed using TUBA over a standard appraisal period of 60 years as specified
in TAG, with 2019 adopted as the appraisal base year.
Travel time benefits from the scheme are calculated by comparing the travel costs between
the Do Minimum and Do Something model assignment results. The time saved is then
monetised, with the value of time varying based upon the purpose of the trip (e.g. an
employer’s business trip has a greater value than a personal business trip). The value of
time is expected to increase over time due to the increase in general wages and the growth
in the economy.
The TUBA default economics input file, which provides parameters, definitions, growth rates
and other factors that are consistent with the May 2019 3 TAG Data Book, has been adopted
in this appraisal.
The vehicle operating costs are calculated in a similar way to the travel time benefits except that distance and time savings are used.
The non-fuel benefits are calculated using the formula below:
= +
• Where D is distance in kilometres;
• T is time in seconds; and
• a and b are parameters defined by the user class.
The fuel benefits are calculated using the formula below:
=
) + 3 (
• a, b, c and d are parameters defined by the user class.
Economic benefits were reviewed on a sector to sector level due to enhance the overall
conclusions. The sector system used for this is shown in Figure 4-4 and Figure 4-5.
Figure 4-4: Zone to Sector System, United Kingdom Extent
3 11th July 2019 Update, including minor revisions
AECOM 20
4.4 Collision Appraisal Accident analysis has been undertaken using COBALT (Cost and Benefit to Accidents –
Light Touch), a computer program developed by the DfT to analyse the impact of a scheme
on accidents as part of economic appraisal for a road scheme. COBALT software 2013.2
and COBALT parameters file version 2018.1 were used for the accident assessment.
Based on the study area and the area of influence of the scheme, the accident analysis has
been undertaken for links within the area outlined in Figure 4-6.
Figure 4-6: COBALT Study Area
As flows are input into COBALT as Annual Average Daily Traffic (AADT), factors were
calculated to scale the hourly model flow results up to 24-hour totals. First, factors were
calculated to scale the peak hour models up to their respective periods. Data from the ten
ATC count sites shown in Figure 4-1 were used for this analysis (The same site used for
annualisation). Average weekday data from a neutral month, from the 13th June to the 27th
June 2016, was used in this analysis. The factors were calculated by dividing the total peak
period flow across all of the ATC sites for this period by the total peak hourly flow. As the IP
model is an average hourly model, a factor of 6 was used to estimate the total flow for the IP
period.
These peak period factors were used to scale the model results up to a 12 hourly total flow,
with the 12 to 24-hour factors calculated by utilising the remaining 12 hours.
The resulting factors are shown in Table 4-3 below.
Table 4-3: Annual Average Daily Traffic Factors
Period Period Definition Factor
IP Average Hour to IP Period 10:00 – 16:00 6.00
PM Peak to PM Period 16:00 – 19:00 2.70
12 to 24 Hour Factor - 1.19
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Table 4-4 presents the change in number of accidents and associated costs for the core scenario.
Table 4-4 – Accident Costs and Benefits – 2010 Prices
Do Minimum
Do Something
Total Casualties (Fatal) 56 54
(Serious) 604 579
(Slight) 5,246 5,043
(Serious) - 25
(Slight) - 203
Total Accident Benefits Saved by Scheme(£000’s) - 8,114
Accident analysis shows that the scheme is forecast to reduce the number of accidents and
casualties over the sixty year appraisal period, resulting in a reduction in accident costs.
This is predominantly a result of re-routeing traffic away from the villages of Roche, Bugle
and Lockengate.
5. Estimation of Costs
5.1 Scheme Costs and Profile The scheme costs (2019 prices Q4) and profile are shown in Table 5-1 and Table 5-2, along
with the present value costs (PVC), discounted to 2010, in 2010 prices, output from TUBA.
Table 5-1: Scheme Costs
2019 2020 2021 2022 2023 2043-
2062 Total
Land 16.3% 83.7% - - - - 100%
Preparation 95.3% 4.7% - - - - 100%
Maintenance - - - - - 5% 100%
The expenditure profile provided is based upon cost estimates provided by Cornwall Council
and their cost consultants (MACE and CORMAC). The cost estimates provide a cost profile
for each financial year prepared in 2019 prices (Q4), which have then been deflated to a
2010 base year in TUBA using a GDP value derived from the May 20194 TAG Data Book.
The costs exclude all recoverable VAT. To ensure all previously incurred costs are
accounted for as part of the appraisal, 2018 costs have been included within the 2019
appraisal year profile.
£1.5 million of construction and supervision costs (in 2019 prices) are forecast to occur
within quarter 1 of 2023, which is marginally after the transport modelled opening year of
2022. These costs relate to complementary measures which would be completed after
scheme opening and therefore would not materially impact the opening assessment year of
2022. However, in the interests of robustness, including discounting calculations, the costs
have been included as part of the 2023 costs profile.
The maintenance cost profile has been based upon discussions with CORMAC, with no
maintenance costs assumed to occur for the first 20 years after scheme opening.
5.2 Risk and Optimism Bias The cost estimates detailed above include risk costs and optimism bias at 3%. This level of
optimism bias is considered appropriate for a scheme at this stage of development, where
detailed scheme designs and a quantified risk assessment have been produced, and is in
accordance with TAG Unit A1.25
4 11th July 2019 Update, including minor revisions 5 Scheme Costs (July 2017)
Overview
Travel time benefits and vehicle operating costs have been calculated Transport Users
Benefit Appraisal (TUBA) software. The parameters used in the economic assessment have
been taken from the TUBA economics file, informed by the TAG Data Book.
The economic assessment of road user benefits has assumed that the opening year for the
scheme will be 2022, with a 60-year appraisal period and a design year of 2037 (opening
year plus fifteen years).
User Classes
The modelled user classes have been converted to the TUBA user classes shown in Table
6-1.
TUBA
User
Class
4 2 LGV
6 4 OGV 1 All 5 HGVs
0.38
7 5 OGV 2 All 0.62
The factors applied to the Light Goods Vehicle (LGV) trip matrix to convert to LGV personal
and LGV freight are default splits from Table A1.3.4 of the November 2018 TAG Data Book.
The factors applied to the Heavy Goods Vehicle (HGV) trip matrix to split into Other Goods
Vehicle (OGV) 1 and OGV2 are from the 2018 National Road Traffic Forecasts which listed
the factors as 0.38 and 0.62 respectively.
Warnings
Before processing in TUBA, a series of checks have been undertaken for consistency
between periods, years and scenarios. TUBA magnifies small differences between
scenarios during the application of the annualisation factors and therefore it was important
to identify and qualify these before the implementation of TUBA.
The TUBA program compares the time and distance between origin and destination zones
and produces a list of errors and warnings when the ratio has surpassed a specified
threshold. A warning occurs when the ratio between the Do Minimum and Do Something is
between 0.666 and 0.333 or between 1.5 and 3. A serious warning occurs when the ratio is
less than 0.333 and greater than 3.
The TUBA program also produces warnings if the average trip journey time or the average
trip distance between a certain origin destination pair exceeds a specified number. The limit
for the journey time is 10 hours and the limit for the trip distance is 1,000 kilometres.
The warnings produced in the TUBA output have been rigorously analysed to check for
inconsistencies and also sense-checked to avoid unrealistic changes occurring. As outlined
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in Section 4.3, results have been reviewed at a sector-level to consider the impact on the
main traffic movements. The results have been checked for consistency between modelled
periods, modelled years and scenarios. This process has determined that there are no
warnings produced from the TUBA runs that are a cause for concern.
6.2 Greenhouse Gases The TUBA program includes an assessment of the change in greenhouse gases produced
by implementing the scheme. The amount of greenhouse gases in each scenario is
calculated using the trip information that has been extracted from the VISUM models.
The greenhouse gas assessed, where the only transport mode is road, is carbon dioxide.
The TUBA program has default values for the amount of carbon produced per litre of fuel.
Carbon dioxide emissions have been extracted from the TUBA output file for every year
during the appraisal period with the latest year being 2081.
The assessment takes into account the future fuel efficiency of vehicles, which is predicted
to increase and also the change in the cost of carbon.
6.3 Local Air Quality and Noise Local air quality and noise impacts have also been assessed in line with current TAG and
Design Manual for Roads and Bridges guidance. In line with guidance, the noise and local
air quality assessments have only been undertaken for the core scenario, hence the same
values have been used for the low growth, core and high growth scenarios. Further details
of the methodologies adopted for each assessment can be found in the Full Business Case
document.
7. Economic Assessment Results
7.1 Travel Time Benefits and Vehicle Operating Costs Table 7-1 shows the total Core scenario benefits over the 60-year appraisal period split into
benefit type and split between trip purposes.
Table 7-1: Transport Benefits by Trip Purpose (£000, discounted to 2010, in 2010 prices)
Purpose Travel Time VOC Fuel VOC
Non-fuel Indirect Tax Total
Business £45,406 -£10,278 -£3,316 £5,705 £37,517
Commuting £24,974 -£2,260 -£2,725 £1,045 £21,034
Other £44,655 -£5,448 -£5,836 £2,613 £35,984
Total £115,035 -£17,986 -£11,877 £9,363 £94,535
The table shows that the majority of benefits created by the scheme are travel time benefits.
This shows that the scheme provides faster journey times between St Austell and the A30
and has reduced travel time costs.
The level of benefits generated for commuting trips is relatively low when compared to the
total benefits. This is due to a combination of a much lower value of time for commuting trips
when compared to business user trips and the relatively low number of commuting trips
observed between the A30 and St Austell.
Profile of Benefits over 60 Year Appraisal Period
Figure 7-1 shows the benefits for each individual year over the 60-year appraisal period.
Figure 7-1: Transport Benefits by Year (£000, discounted to 2010, in 2010 prices)
-1,000
-500
0
500
1,000
1,500
2,000
2,500
3,000
3,500
o ta
Core Scenario Benefits, by Year
User Time User Charges: Vehicle Fuel Operating Cost: Non-fuel Indirect Taxes
Benefits by Travel Time Saving
Table 7-2 shows the travel time benefits split by travel time saving.
Table 7-2: Total Benefits by Travel Time Saving (£000, discounted to 2010, in 2010 prices)
Purpose < -5 mins -5 to -2 mins
-2 to 0 mins
0 to 2 mins 2 to 5 mins > 5 mins
Business -£1,908 £-2,048 -£12,737 £15,109 £43,734 £3,254
Commuting -£2 -£8 -£8,255 £11,555 £21,109 £574
Other -£2 -£234 -£18,968 £20,614 £42,561 £685
The above table shows that the majority of travel time benefits are for time savings between
2 and 5 minutes.
High and Low Growth Scenario Results
In addition to the core growth scenario presented above, the traffic forecasting process also
produced future year traffic models for high and low growth scenarios using the standard
TAG methodology (outlined in AECOM’s TFR Section 5). Transport benefits by journey
purpose have been calculated for both scheme options in the high and low growth
scenarios; Table 7-3 and Table 7-4 shows the results of this analysis.
Table 7-3: Low Growth Transport Benefits by Trip Purpose (£000, discounted to 2010, in 2010
prices)
Business £47,258 -£10,558 -£3,141 £5,873 £39,432
Commuting £22,826 -£2,173 -£2,543 £1,014 £19,124
Other £45,434 -£5,055 -£5,365 £2,431 £37,445
Total £115,518 -£17,786 -£11,049 £9,318 £96,001
Table 7-4: High Growth Transport Benefits by Trip Purpose (£000, discounted to 2010, in 2010
prices)
Business £48,695 -£10,440 -£3,642 £5,793 £40,406
Commuting £28,039 -£2,335 -£2,942 £1,065 £23,827
Other £48,920 -£5,474 -£6,245 £2,586 £39,787
Total £125,654 -£18,249 -£12,829 £9,444 £104,020
The results show that the high growth scenario is shown to generate more benefit than the
core growth scenario. This is expected as the increased traffic levels of the caused by the
increased traffic growth will increase congestion within the model and therefore increase the
benefit of the scheme.
The Low Growth scenario is shown to generate similar benefits to the Core Growth.
7.2 Monetised Environmental Assessment Results The TUBA calculated impact on greenhouse gases for the scheme present a predicted
disbenefit of £4.4 million. This disbenefit results from the scheme increasing speeds along
the A30 to St Austell road and therefore the average amount of fuel used for each trip.
Local air quality benefits of £1.1 million and noise impacts of £23,220 have also been
forecast from the non-TUBA assessments outlined in Section 6.3.
7.3 Reliability The Outline Business Case Economic Appraisal Report previously assessed the impact of
the scheme in improving journey time reliability. This assessment was conducted using the
stress-based approach outlined in TAG Unit A1.3.
The assessment was found to show that whilst the scheme does have a beneficial effect in
terms of reducing driver stress, given the need to restrict the assessment to the 75%-125%
range, the overall result is neutral. No monetised benefits for reliability were therefore
included in the OBC economic appraisal.
Table 7-5 presents the OBC journey time reliability results.
Table 7-5: Outline Business Case Journey Time Reliability Assessment Results
Do Minimum Do Something
With Scheme Stress
Difference in Stress 0% 0%
Overall Assessment Neutral
7.4 Transport Economic Efficiency The Transport Economic Efficiency (TEE) table provides a summary of the travel time and
vehicle operating cost benefits. The benefits are summarised by trip purpose. This includes
the benefits generated from the main TUBA assessment, maintenance and construction
scenarios. The TEE table for the core growth scenario for the scheme is shown in Table 7-6.
Low and high growth results can be found in Appendix A1.
Table 7-6: Economic Efficiency of the Transport System Results, Core Growth Scenario
Non-business: Commuting
User benefits
£85,172,000
7.5 Public Accounts The Public Accounts table details the source of the scheme costs and have been
summarised by local and central government. The Public Accounts table for the core growth
scenario is shown in Table 7-7. The indirect tax revenue is reported as a negative number,
this is consistent with the Public Accounts section of the TUBA output file. This is then
represented as a positive number in the AMCB table indicating an increase in indirect tax
revenue.
Local Government Funding
Broad Transport Budget £61,849,000
Wider Public Finances -£9,364,000
7.6 Analysis of Monetised Costs and Benefits The benefits from each individual assessment have been totalled to create the Present
Value Benefits (PVB) of the scheme. They have been summarised in the AMCB table along
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with the PVC and the initial unadjusted Benefit-Cost Ratio (BCR). The AMCB table for the
core growth scenario for the scheme is shown in Table 7-8. Low and high growth results can
be found in Appendix A2.
Table 7-8: Analysis of Monetised Costs and Benefits, Core Growth Scenario
Noise £ 23,220
£ 19,989,000
£ 31,812,000
Broad Transport Budget £ 61,849,000
Overall Impacts
Initial Unadjusted Benefit to Cost Ratio (BCR) 1.61
The results show that the scheme provides significant benefits to transport users, resulting
from the significant improvement in the performance of the A391 provided by the scheme.
The scheme produces an initial unadjusted BCR of 1.61, which represents Medium value-
for-money6.
7.7 OBR and Fleet Forecast Sensitivity Test Results
Additional sensitivity testing has been undertaken, at the request of the DfT, to understand
how changes in Office for Budget Responsibility (OBR) and fleet composition forecasts
impact the core growth scenario economic appraisal. The OBR sensitivity test TUBA
parameters were provided by the DfT in August 2020.
As suggested by the DfT, a proportionate approach to undertaking the economic appraisal
sensitivity test, hence the transport models have not been re-assigned. The OBR sensitivity
test TUBA parameters have been applied to the core growth scenario.
The TEE and AMCB result for the OBR Sensitivity Test are presented in Table 7-9 and
Table 7-10.
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Table 7-9: Economic Efficiency of the Transport System OBR Sensitivity Test Results, Core
Growth Scenario
User charges £0 £0
NET COMMUTING £16,818,000 £19,989,000
NET OTHER £27,796,000 £33,371,000
Subtotal £26,138,000 £31,812,000
Private sector provider
Revenue £0 £0
£70,752,000 £85,172,000
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Table 7-10: Analysis of Monetised Costs and Benefits, OBR Sensitivity Test, Core Growth
Scenario
Greenhouse Gases -£ 4,019,000 -£ 4,384,000
£ 16,818,000 £ 19,989,000
Economic Efficiency: Business Users and Providers
£ 26,138,000 £ 31,812,000
Present Value of Benefits (PVB) £ 84,825,548 £ 99,414,548
Broad Transport Budget £ 61,849,000 £ 61,849,000
Present Value of Costs (PVC) £ 61,849,000 £ 61,849,000
Overall Impacts
Initial Unadjusted Benefit to Cost Ratio (BCR) 1.37 1.61
* Noise, Local Air Quality and Accident Benefits have not been adjusted for the OBR Sensitivity Test
The results in Table 7-9 and Table 7-10 demonstrate that whilst greenhouse gases and
vehicle operating cost are positively impacted by the OBR sensitivity test, travel time and
wider public finances are forecast to be negatively impacted. The key changes to the
economic appraisal for the OBR sensitivity test relative to the Core Growth Scenario are:
• Greenhouse Gases: 8% reduction in dis-benefits;
• Economic Efficiency: Consumer Users (Commuting): 16% reduction in benefits;
• Economic Efficiency: Consumer Users (Other): 17% reduction in benefits;
• Economic Efficiency: Business Users and Providers: 18% reduction in benefits;
• Wider Public Finances: 6% reduction in benefits; and
• Present Value of Benefits (PVB): 15% reduction in benefits.
There is also a resulting reduction in both the NPV and the initial unadjusted BCR. An
adjusted BCR has not been calculated as part of the OBR sensitivity test economic
appraisal.
The sensitivity test results still show that the scheme provides significant benefits to
transport users, resulting from the significant improvement in the performance of the A391
provided by the scheme.
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8. Conclusion This report sets out the methodology used to appraise the St Austell to A30 Link Road
scheme. The methodology complies with DfT guidance set out in TAG.
The economic appraisal has comprised the following key elements:
• Travel time benefits and vehicle operation costs using TUBA;
• Accident analysis using COBALT;
• Estimation of Costs; and
• Analysis of Monetised Costs and Benefits
The assessment presented in this report shows that for the core scenario the scheme offers
Medium Value for Money with an initial unadjusted benefit to cost ratio of 1.61. The low
growth initial unadjusted benefit to cost ratio is 1.62, whilst the high growth initial unadjusted
benefit to cost ratio is 1.57.
The Value for Money Benefit has been determined based on the initial unadjusted BCR,
using the information in the following table (DfT – Value for Money Framework).
Appendix A1: Transport Economic Efficiency
Low Growth Non-business: Commuting
£86,685,000
£94,577,000
Low Growth
Noise £ 23,220
Economic Efficiency: Business Users and Providers £ 33,560,000
Wider Public Finances £ 9,317,000
Overall Impacts
In line with guidance, the noise and local air quality assessments have only been undertaken for the core
scenario, hence the same values have been used for the low growth, core and high growth scenarios
High Growth
Noise £ 23,220
Economic Efficiency: Business Users and Providers £ 34,613,000
Wider Public Finances £ 9,444,000
Overall Impacts
In line with guidance, the noise and local air quality assessments have only been undertaken for the core
scenario, hence the same values have been used for the low growth, core and high growth scenarios
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Economic Assessment Report
Economic Assessment Report
August 2020
The existing route between St Austell and the A30 is of a variable standard, passing through a number of villages, with congestion and delays leading to poor journey time reliability. The new route is needed to help meet Cornwall Council’s objectives of relieving traffic issues along the current route and unlocking economic potential within St Austell and the surrounding area.
Cornwall Council and local stakeholders hold an aspiration to create an improved strategic link between St Austell and the A30. St Austell is Cornwall’s largest town and is not currently served by a high-quality road link to the A30. The proposed scheme is a new high-quality, single carriageway route linking St Austell to the A30 and to divert traffic (including Heavy Goods Vehicles) away from settlements along the existing route(s).
Cornwall Council and local stakeholders hold an aspiration to create an improved strategic link between St Austell and the A30. St Austell is Cornwall’s largest town and is not currently served by a high-quality road link to the A30. The proposed scheme is a new high-quality, single carriageway route linking St Austell to the A30 and to divert traffic (including Heavy Goods Vehicles) away from settlements along the existing route(s).
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Cornwall Council’s overarching aims for the scheme are to:
AECOM have developed forecast year models, for assessment years of 2022 and 2037, to represent the traffic patterns that would be expected to occur with the addition of the proposed scheme. Further details on the models utilised in this appraisal can be found in AECOM’s Traffic Forecasting Report (dated September 2019).
This economic appraisal has utilised the most recent version of the Department for Transport’s (DfT) Transport User Benefits Appraisal (TUBA) version 1.9.13 (July 2019) and Cost and Benefits to Accidents – Light Touch (COBALT) software version 2013.02 and COBALT parameters file version 2018.1. The TUBA appraisal includes monetisation of travel time benefits, vehicle operating costs, and greenhouse gases. The COBALT assessment provided a monetised appraisal of potential collision changes resulting from the
This economic appraisal has utilised the most recent version of the Department for Transport’s (DfT) Transport User Benefits Appraisal (TUBA) version 1.9.13 (July 2019) and Cost and Benefits to Accidents – Light Touch (COBALT) software version 2013.02 and COBALT parameters file version 2018.1. The TUBA appraisal includes monetisation of travel time benefits, vehicle operating costs, and greenhouse gases. The COBALT assessment provided a monetised appraisal of potential collision changes resulting from the
The assessment presented in this report shows that the scheme offers Medium value for money with an initial unadjusted benefit to cost ratio of 1.61.
The assessment presented in this report shows that the scheme offers Medium value for money with an initial unadjusted benefit to cost ratio of 1.61.
Cornwall Council and local stakeholders have an aspiration to create an improved strategic link between St Austell and the A30. Although St Austell is Cornwall’s largest town, it is not currently served by a high-quality road link to the A30. The current route is the A391, which is a variable standard single carriageway route passing through a number of settlements between St Austell and the A30.
Cornwall Council and local stakeholders have an aspiration to create an improved strategic link between St Austell and the A30. Although St Austell is Cornwall’s largest town, it is not currently served by a high-quality road link to the A30. The current route is the A391, which is a variable standard single carriageway route passing through a number of settlements between St Austell and the A30.
Given its status as the largest town in Cornwall, St Austell is a major attractor of trip origins and destinations within mid-Cornwall, with heavy industry within the China Clay Area attracting a high number of Heavy Goods Vehicle (HGV) trips. The low standard of the current route connections to the A30 result in congestion, delays and traffic safety issues within affected areas. The route requires improvement to meet Cornwall Council’s objectives of improving journey reliability, safety and raising econom
Given its status as the largest town in Cornwall, St Austell is a major attractor of trip origins and destinations within mid-Cornwall, with heavy industry within the China Clay Area attracting a high number of Heavy Goods Vehicle (HGV) trips. The low standard of the current route connections to the A30 result in congestion, delays and traffic safety issues within affected areas. The route requires improvement to meet Cornwall Council’s objectives of improving journey reliability, safety and raising econom
The scheme is inherently expected to impact the travel arrangements within St Austell, settlements along the current route, and to the wider transport network within Cornwall. Travel patterns would be anticipated to be affected because of route performance improvements, attracting traffic from other routes. The traffic model has been designed to forecast the potential impact of these travel patterns across a wide area.
The scheme is inherently expected to impact the travel arrangements within St Austell, settlements along the current route, and to the wider transport network within Cornwall. Travel patterns would be anticipated to be affected because of route performance improvements, attracting traffic from other routes. The traffic model has been designed to forecast the potential impact of these travel patterns across a wide area.
The overarching aim of the scheme is to provide a higher quality link between St Austell and the A30, and to divert traffic (including HGVs) away from the towns and villages along the existing routes.
The overarching aim of the scheme is to provide a higher quality link between St Austell and the A30, and to divert traffic (including HGVs) away from the towns and villages along the existing routes.
The scheme objectives are aligned with the key policies identified within Cornwall Council’s regional transport policies, and the Cornwall and Isles of Scilly Strategic Economic Plan (Vision 2030).
The scheme objectives are aligned with the key policies identified within Cornwall Council’s regional transport policies, and the Cornwall and Isles of Scilly Strategic Economic Plan (Vision 2030).
A detailed review of the proposed scheme can be found in the Traffic Forecasting Report Section 6.3, but it broadly follows the ‘Roche Option’ assessed in the Outline Business Case. The highway has been designed to accommodate vehicles travelling at 60mph and will replace the B3274 from Stenalees to Trezaise to form a bypass around Roche, linking to the old A30 west of Victoria (Figure 2-1).
A detailed review of the proposed scheme can be found in the Traffic Forecasting Report Section 6.3, but it broadly follows the ‘Roche Option’ assessed in the Outline Business Case. The highway has been designed to accommodate vehicles travelling at 60mph and will replace the B3274 from Stenalees to Trezaise to form a bypass around Roche, linking to the old A30 west of Victoria (Figure 2-1).
In general, the St Austell to A30 Link Road will be single carriageway, with climber lanes provided at key locations as required. Four new roundabouts will be constructed at Stenalees, Trezaise, Harmony Road and at the old A30 (C0120).
In general, the St Austell to A30 Link Road will be single carriageway, with climber lanes provided at key locations as required. Four new roundabouts will be constructed at Stenalees, Trezaise, Harmony Road and at the old A30 (C0120).
This TFR sets out information relating to the development of the forecast scenarios and is structured as follows:
This TFR sets out information relating to the development of the forecast scenarios and is structured as follows:
This chapter provides an overview of the Base Year model. The Local Model Validation Report (March 2017) details the base model that has been developed by the consultants PTV to inform the appraisal of the scheme.
This chapter provides an overview of the Base Year model. The Local Model Validation Report (March 2017) details the base model that has been developed by the consultants PTV to inform the appraisal of the scheme.
The Base Year model formed the basis for the forecast models detailed in this report. Forecast models have been built for 2022 (the proposed opening year of the scheme) and 2037 (future case fifteen years from the opening year). The forecast models detailed in this report have been built in compliance with Department for Transport TAG Unit M4 ‘Forecasting and Uncertainty’ (May 2018).
The Base Year model formed the basis for the forecast models detailed in this report. Forecast models have been built for 2022 (the proposed opening year of the scheme) and 2037 (future case fifteen years from the opening year). The forecast models detailed in this report have been built in compliance with Department for Transport TAG Unit M4 ‘Forecasting and Uncertainty’ (May 2018).
Neutral month peak and inter-peak time periods have been modelled to fully understand the operation and economic benefits of the proposed scheme. The modelled time periods are shown in Table 3-1.
Neutral month peak and inter-peak time periods have been modelled to fully understand the operation and economic benefits of the proposed scheme. The modelled time periods are shown in Table 3-1.
The main study area covers St Austell and includes the towns of Roche and Bugle to the north, Lostwithiel and Fowey to the east, Mevagissey to the south, and St Stephens and St Dennis to the west. The extent of the detailed study area is illustrated in Figure 3-1 and Figure 3-2.
The main study area covers St Austell and includes the towns of Roche and Bugle to the north, Lostwithiel and Fowey to the east, Mevagissey to the south, and St Stephens and St Dennis to the west. The extent of the detailed study area is illustrated in Figure 3-1 and Figure 3-2.
The remainder of Cornwall has been modelled in varying levels of detail (Figure 3-3). This area is not as detailed as the main study area but allows for the control of traffic routes into Cornwall. The wider model area includes the rest of the UK (Figure 3-4). Outside of Devon and Cornwall the zones become much larger.
The remainder of Cornwall has been modelled in varying levels of detail (Figure 3-3). This area is not as detailed as the main study area but allows for the control of traffic routes into Cornwall. The wider model area includes the rest of the UK (Figure 3-4). Outside of Devon and Cornwall the zones become much larger.
The Base Year traffic model was used as the basis of future year traffic forecasts for the opening year (2022) and design year (2037). Future year models were produced for core, low and high growth scenarios.
The Base Year traffic model was used as the basis of future year traffic forecasts for the opening year (2022) and design year (2037). Future year models were produced for core, low and high growth scenarios.
A good level of convergence has been achieved for nearly all modelled scenarios, time periods and years. The forecast assignments can therefore be considered robust for the purposes of the economic assessment.
A good level of convergence has been achieved for nearly all modelled scenarios, time periods and years. The forecast assignments can therefore be considered robust for the purposes of the economic assessment.
The future year traffic forecasts produced from the forecasting procedures outlined in AECOM’s Traffic Forecasting Report (dated September 2019) have been utilised in this assessment.
The future year traffic forecasts produced from the forecasting procedures outlined in AECOM’s Traffic Forecasting Report (dated September 2019) have been utilised in this assessment.
The economic appraisal has utilised the most recent version of the Department for Transport’s Transport User Benefits Appraisal (TUBA) version 1.9.13 (July 2019) and Cost and Benefits to Accidents – Light Touch (COBALT) software version 2013.02 and COBALT parameters file version 2018.1. The TUBA appraisal includes monetisation of travel time benefits, vehicle operating costs, and greenhouse gases. The COBALT assessment provided a monetised appraisal of potential collision changes resulting from the scheme.
The economic appraisal has utilised the most recent version of the Department for Transport’s Transport User Benefits Appraisal (TUBA) version 1.9.13 (July 2019) and Cost and Benefits to Accidents – Light Touch (COBALT) software version 2013.02 and COBALT parameters file version 2018.1. The TUBA appraisal includes monetisation of travel time benefits, vehicle operating costs, and greenhouse gases. The COBALT assessment provided a monetised appraisal of potential collision changes resulting from the scheme.
Economic appraisal requires a consideration of the benefits to all road users, many of which will not be travelling at a time represented by the transport model. Benefits per vehicle vary throughout the day and year to the extent that traffic levels impact on the benefit per vehicle.
Economic appraisal requires a consideration of the benefits to all road users, many of which will not be travelling at a time represented by the transport model. Benefits per vehicle vary throughout the day and year to the extent that traffic levels impact on the benefit per vehicle.
The calculation of user benefits requires the calculation of annualisation factors to quantify the way in which the scheme might affect those travelling during weekdays outside of the modelled hours or on weekends and public holidays.
The calculation of user benefits requires the calculation of annualisation factors to quantify the way in which the scheme might affect those travelling during weekdays outside of the modelled hours or on weekends and public holidays.
The Inter Peak (IP) has been used to reflect the off-peak period, weekends and public holidays. Periods of low flow, when congestion would not be expected, have been excluded. The IP was considered to be representative based on the assumption that the traffic levels during this period provide an appropriate representation of traffic conditions and journey times during off-peak and holiday periods.
The Inter Peak (IP) has been used to reflect the off-peak period, weekends and public holidays. Periods of low flow, when congestion would not be expected, have been excluded. The IP was considered to be representative based on the assumption that the traffic levels during this period provide an appropriate representation of traffic conditions and journey times during off-peak and holiday periods.
The annualisation factors have been calculated using Automated Traffic Count (ATC) data from the ten site locations shown in Figure 4-1. Data was used from two weeks in June 2016 (13th to 27th) to calculate the annualisation factors using the guidance set out in TAG Unit A1.31 and in accordance with discussions with the Department for Transport (DfT)2.
The annualisation factors have been calculated using Automated Traffic Count (ATC) data from the ten site locations shown in Figure 4-1. Data was used from two weeks in June 2016 (13th to 27th) to calculate the annualisation factors using the guidance set out in TAG Unit A1.31 and in accordance with discussions with the Department for Transport (DfT)2.
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This document has been prepared by AECOM Limited (“AECOM”) for sole use of our client (the “Client”) in accordance with generally accepted consultancy principles, the budget for fees and the terms of reference agreed between AECOM and the Client. Any information provided by third parties and referred to herein has not been checked or verified by AECOM, unless otherwise expressly stated in the document. No third party may rely upon this document without the prior and express written agreement of AECOM.
This document has been prepared by AECOM Limited (“AECOM”) for sole use of our client (the “Client”) in accordance with generally accepted consultancy principles, the budget for fees and the terms of reference agreed between AECOM and the Client. Any information provided by third parties and referred to herein has not been checked or verified by AECOM, unless otherwise expressly stated in the document. No third party may rely upon this document without the prior and express written agreement of AECOM.
Table of Contents
Table of Contents
Table of Contents
1. Executive Summary
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• Reduce journey times and improve journey reliability between Newquay, the A30 and St Austell;
• Create a better link between two of Cornwall’s largest towns (St Austell and Newquay), the airport and Aerohub Enterprise Zone;
• Make access to Cornwall’s new, large employment sites easier, therefore supporting the expanding employment sites Victoria Business Park, Indian Queens Industrial Estate and the Aerohub Enterprise Zone;
• Improve the competitiveness of St Austell as a location to do business via new employment space or interest in land that can be developed into employment space;
• Support housing growth, including the delivery West Carclaze Garden Village ecocommunity, which is expected to create 1,500 new homes and 500 jobs; and
• Support the regeneration of Roche, Bugle and St Dennis by addressing traffic related issues within the villages and creating better opportunities for businesses.
2. Study Overview
2. Study Overview
2.2 Scheme Objectives
2.2 Scheme Objectives
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St Austell and Newquay, the airport and Aerohub Enterprise Zone;
• Make it easier to access Cornwall’s new, large employment sites and support the expanding employment sites Victoria Business Park, Indian Queens Industrial Estate and the Aerohub Enterprise Zone;
• Improve competitiveness of St Austell as a location to do business via new employment space or interest in land that can be developed into employment space;
• Support housing growth, including the delivery West Carclaze Garden Village ecocommunity (with the creation 1,500 new homes and 500 jobs); and
2.3 Assessment Option
2.3 Assessment Option
3. Economic Assessment Approach
3. Economic Assessment Approach
Table 3
Table 3
Table
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• Major and intermediate routes in Devon, with slightly more detail in Plymouth and Exeter; and
• Major routes covering the rest of the UK.
Figure
4.1 Economic Appraisal
4.1 Economic Appraisal
4.2 Annualisation Factors
4.2 Annualisation Factors
1 User and Provider Impacts (March 2017)
1 User and Provider Impacts (March 2017)
2 St Austell A30 Link Road – DfT Review Meeting Minutes (dated 11th April 2019)
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Based upon the traffic profiles shown in Figure 4-2 and Figure 4-3, separate factors were calculated for the three modelled time periods on the assumption that each modelled period will represent the following days and times:
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The method outlined above resulted in the modelled hour to peak period factors presented in Table 4-1.
The following breakdown of days within a year has been adopted in the calculation of annualisation factors:
A summary of the annualisation factors for the modelled time periods are shown in Table 4-2.
A summary of the annualisation factors for the modelled time periods are shown in Table 4-2.
Travel time benefits and the impact on vehicle operating costs for the proposed scheme have been assessed using TUBA over a standard appraisal period of 60 years as specified in TAG, with 2019 adopted as the appraisal base year.
Travel time benefits and the impact on vehicle operating costs for the proposed scheme have been assessed using TUBA over a standard appraisal period of 60 years as specified in TAG, with 2019 adopted as the appraisal base year.
Travel time benefits from the scheme are calculated by comparing the travel costs between the Do Minimum and Do Something model assignment results. The time saved is then monetised, with the value of time varying based upon the purpose of the trip (e.g. an employer’s business trip has a greater value than a personal business trip). The value of time is expected to increase over time due to the increase in general wages and the growth in the economy.
Travel time benefits from the scheme are calculated by comparing the travel costs between the Do Minimum and Do Something model assignment results. The time saved is then monetised, with the value of time varying based upon the purpose of the trip (e.g. an employer’s business trip has a greater value than a personal business trip). The value of time is expected to increase over time due to the increase in general wages and the growth in the economy.
The TUBA default economics input file, which provides parameters, definitions, growth rates and other factors that are consistent with the May 2019 3 TAG Data Book, has been adopted in this appraisal.
The TUBA default economics input file, which provides parameters, definitions, growth rates and other factors that are consistent with the May 2019 3 TAG Data Book, has been adopted in this appraisal.
Figure
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1: Location of Traffic Count Sites Used in Annualisation Factor Calculations
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peak (0500 to 0700 and 1900 to 0000) weekends and public holidays; and
Figure
Figure 4
Figure 4
Figure
Table
THead
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=(+ ()+2 ()+3 ())
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Figure
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Accident analysis has been undertaken using COBALT (Cost and Benefit to Accidents – Light Touch), a computer program developed by the DfT to analyse the impact of a scheme on accidents as part of economic appraisal for a road scheme. COBALT software 2013.2 and COBALT parameters file version 2018.1 were used for the accident assessment.
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Based on the study area and the area of influence of the scheme, the accident analysis has been undertaken for links within the area outlined in Figure 4-6.
Figure
As flows are input into COBALT as Annual Average Daily Traffic (AADT), factors were calculated to scale the hourly model flow results up to 24-hour totals. First, factors were calculated to scale the peak hour models up to their respective periods. Data from the ten ATC count sites shown in Figure 4-1 were used for this analysis (The same site used for annualisation). Average weekday data from a neutral month, from the 13th June to the 27th June 2016, was used in this analysis. The factors were calculated
These peak period factors were used to scale the model results up to a 12 hourly total flow, with the 12 to 24-hour factors calculated by utilising the remaining 12 hours.
These peak period factors were use

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St Austell to A30 Link