Detailed option appraisal
Introduction
This section of the report presents the findings from the appraisal of the options and Future scenarios. For comparison purposes the options appraisal considers the status quo as a Do-minimum scenario (i.e. no changes to National Speed Limits on rural single, dual carriageway or motorways are made).
Option 1
This option aims to improve road safety and reduce speed differential on single carriageways.
- On single carriageways:
- Cars and motorcycles would have a decreased speed limit of 50mph; and
- Goods vehicles (>7.5t) would have an increased speed limit of 50mph.
- On dual carriageways as follows:
- No alterations to speed limits proposed.
- On motorways:
- No alterations to speed limits proposed.
Presented in Table 6-1 is an overview of the options Appraisal for Option 1 and future scenarios.
| Category appraised | 100% Compliance - Without Policy | 100% Compliance - With Policy | Realistic Compliance - Without Policy | Realistic Compliance - With Policy |
|---|---|---|---|---|
| Environment - noise and vibration | Minor benefit | Minor benefit | No impact or benefit | No impact or benefit |
| Environment - local air quality (airborne particulate matter) | No impact or benefit | No impact or benefit | No impact or benefit | No impact or benefit |
| Environment - local air quality (Nitrous Oxide emissions) | No impact or benefit | No impact or benefit | No impact or benefit | No impact or benefit |
| Climate Change - Greenhouse Gas Emission | No impact or benefit | No impact or benefit | No impact or benefit | No impact or benefit |
| Health, Safety and Wellbeing - accidents (All severity) | Moderate benefit | Moderate benefit | Moderate benefit | Moderate benefit |
| Economy - Economic efficiency of the transport system | Major negative impact | Moderate negative impact | Moderate negative impact | Minor negative impact |
| Comparative Access by Geographic Location | No impact or benefit | No impact or benefit | No impact or benefit | No impact or benefit |
Environment – Noise and Vibration
When considered “with policy” noise level changes will range from no benefit or impact to minor beneficial in this option, with a maximum predicted reduction in noise level of 2.7 dBA, for 100% compliance, and 0.9 dBA for realistic compliance, due to changes in average speed and traffic flows.
When considered “without policy”, noise level changes will range from no benefit or impact to minor beneficial in this option, with a maximum predicted reduction in noise level of 1.9 dBA, for 100% compliance, and 0.9 dBA for realistic compliance, due to changes in average speed and traffic flows. The magnitude of changes in noise level evaluated as a comparison between the future appraisals and do-nothing scenarios in the year of assessment.
An overview of the Noise assessment is presented in Table 6-2, with further details provided in Appendix C.
| Category appraised | 100% Compliance - Without Policy | 100% Compliance - With Policy | Realistic Compliance - Without Policy | Realistic Compliance - With Policy |
|---|---|---|---|---|
| Environment - noise impact | 1.9 dB | 2.7 dB | 0.9 dB | 0.9 dB |
Environment – local air quality (airborne matter and Nitrous Oxide emissions)
Both the “with policy” and “without policy” futures for the 100% compliance and realistic modelling scenarios show no benefit or impact in national road NOx, PM10 and PM2.5 emissions for 2030. A brief summary of the findings for Option 1 is outlined in Section 7.3 with the full results are given in Appendix D for 2025, 2030 and 2045.
The 2030 data in Table 6-3 represents the potential change in traffic emissions five years after implementation of the scheme allowing for realistic uptake (which is unlikely to be immediate). The impacts for 2025 and 2045 are presented in Appendix D.
| Category appraised | 100% Compliance - Without Policy | 100% Compliance - With Policy | Realistic Compliance - Without Policy | Realistic Compliance - With Policy |
|---|---|---|---|---|
| Change in NOx emissions (kg/year) | -13,777 | -9,580 | -9,142 | -6,683 |
| Change in PM10 emissions (kg/year) | 8,419 | 7,987 | 4,432 | 4,122 |
| Change in PM2.5 emissions (kg/year) | 3,658 | 3,536 | 1,915 | 1,817 |
Climate Change – Greenhouse Gas Emissions
The various future scenarios considered do not show any significant change in greenhouse gas emissions. An overview of the Greenhouse Gas Emissions assessment is presented in Table 6-4, with further details presented in Appendix E.
| Category appraised | 100% Compliance - Without Policy | 100% Compliance - With Policy | Realistic Compliance - Without Policy | Realistic Compliance - With Policy |
|---|---|---|---|---|
| Total Changes CO2e emissions (tonnes) over 60-year appraisal period following opening (t) | 427,158.23 | 190,588.58 | 257,280.66 | 137,809.78 |
| Percentage Change | -0.28% | -0.08% | -0.09% | -0.06% |
Table 6-5 – Option 1 Collision Savings Future Scenarios
Health, Safety and Wellbeing – Accidents (All severity)
All future scenarios under Option 1 show significant reductions in the number of collisions. These impacts are significantly increased under the 100% compliance futures. An overview of the envisaged collision savings is presented in Table 6-5, further details provided in Appendix F.
| Category appraised | 100% Compliance - Without Policy | 100% Compliance - With Policy | Realistic Compliance - Without Policy | Realistic Compliance - With Policy |
|---|---|---|---|---|
| Collision Savings in first year (Core Scenario) |
Fatal - 7 Serious - 28 Slight - 13 Total - 48 |
Fatal - 7 Serious - 26 Slight - 12 Total - 45 |
Fatal - 4 Serious - 15 Slight - 7 Total - 26 |
Fatal - 4 Serious - 14 Slight - 6 Total - 25 |
| Collision savings over 60 year assessment period (Core Scenario) |
Fatal - 415 Serious - 1743 Slight - 901 Total - 3059 |
Fatal - 294 Serious - 1237 Slight - 637 Total - 2167 |
Fatal - 243 Serious - 1034 Slight - 548 Total - 1826 |
Fatal - 170 Serious - 720 Slight - 378 Total - 1267 |
| Collision Savings in first year (Uplift Scenario) |
Fatal - 8 Serious - 28 Slight - 13 Total - 49 |
Fatal - 8 Serious - 26 Slight - 12 Total - 46 |
Fatal - 5 Serious - 15 Slight - 7 Total - 27 |
Fatal - 5 Serious - 14 Slight - 6 Total - 25 |
| Collision savings over 60 year assessment period (Uplift Scenario) |
Fatal - 489 Serious - 1743 Slight - 901 Total - 3134 |
Fatal - 350 Serious - 1237 Slight - 637 Total - 2224 |
Fatal - 293 Serious - 1034 Slight - 548 Total - 1875 |
Fatal - 206 Serious - 720 Slight - 378 Total - 1303 |
Economy – Economic efficiency of the transport system
Option 1 is expected to result in a minor to moderate adverse effect for economic efficiency across the future scenarios, with the primary type of user impacted being ‘other’ users while commuting and business users are impacted equally in person hours. However, when monetised the most significant economic impact is on business users due to the high value of their time.
If the 100% compliance future was achieved it would be expected that Option 1 would increase in disbenefit however, it would still be expected to be a moderate adverse.
An overview of economic assessment is presented in Table 6-6, with further detail presented in Appendix G and Appendix I.
| Transport Economic Efficiency (TEE) Benefits | 100% Compliance - Without Policy | 100% Compliance - With Policy | Realistic Compliance - Without Policy | Realistic Compliance - With Policy |
|---|---|---|---|---|
| Consumer - commuting user benefits; Travel Time | -113 | -81 | -59 | -42 |
| Consumer - commuting user benefits; Vehicle operating costs | 7 | 4 | 4 | 3 |
| Consumer - commuting user benefits; Subtotal | -106 | -77 | -55 | -39 |
| Consumer - other user benefits; Travel Time | -126 | -96 | -64 | -47 |
| Consumer - other user benefits; Vehicle operating costs | 11 | 5 | 7 | 3 |
| Consumer - other user benefits; Subtotal | -116 | -91 | -58 | -44 |
| Business benefits; Travel Time | -204 | -195 | -100 | -91 |
| Business benefits; Vehicle operating costs | -28 | -24 | -14 | -11 |
| Business benefits; Subtotal | -231 | -219 | -114 | -102 |
| Total TEE benefit | -453 | -387 | -227 | -185 |
Comparative Access by Geographic Location
The fisheries industry is a key industry within Scotland and the impacts on these journey times have been assessed to understand the likely impact. These trips have been assessed from key locations to nearby the Scotland border at Gretna Green. The realistic compliance results are presented in Table 6-7 below for the PM peak.
| From | To | Do Minimum | Option 1 | Difference |
|---|---|---|---|---|
| Aberdeen | Gretna Green | 04:10:10 | 04:10:27 | 00:00:17 |
| Scrabster | Gretna Green | 06:16:10 | 06:20:17 | 00:04:07 |
| Ullapool | Gretna Green | 05:05:40 | 05:07:26 | 00:01:45 |
| Uig | Gretna Green | 08:27:08 | 08:28:16 | 00:01:08 |
| Oban | Gretna Green | 03:40:04 | 03:41:11 | 00:01:08 |
Table 6-7 above shows the largest increase for the route from Scrabster to Gretna is an approximate four-minute increase to the current six-hour journey time. Therefore, it is unlikely the long HGV routes will be severely impacted by this option. Although the option increases the speed limit of HGV’s on single carriageway, HGV traffic will interact with other vehicles that will have their speed limit reduced.
Other future scenarios considered result in trivial differences in journey times from the presented durations.
Option 2
This option aims to improve road safety and reduce speed differential on Scotland’s Road network.
- On single carriageways:
- Cars and motorcycles would have a decreased speed limit of 50mph; and
- Goods vehicles (>7.5t) would have an increased speed limit of 50mph.
- On dual carriageways as follows:
- Cars and motorcycles would have a decreased speed limit of 60mph; and
- Goods vehicles (>7.5t) would have an increased speed limit of 60mph.
- On motorways:
- All vehicles limited to 60mph.
Table 6-8 presents and overview of the options Appraisal for Option 2 and future scenarios.
| Category appraised | 100% Compliance - Without Policy | 100% Compliance - With Policy | Realistic Compliance - Without Policy | Realistic Compliance - With Policy |
|---|---|---|---|---|
| Environment - noise and vibration | Minor benefit | Minor benefit | No benefit or impact | No benefit or impact |
| Environment - local air quality (airborne particulate matter) | No benefit or impact | No benefit or impact | No benefit or impact | No benefit or impact |
| Environment - local air quality (Nitrous Oxide emissions) | Moderate benefit | Moderate benefit | Minor benefit | Minor benefit |
| Climate Change - Greenhouse Gas Emission | Minor benefit | Minor benefit | Minor benefit | Minor benefit |
| Health, Safety and Wellbeing - accidents (All severity) | Major benefit | Major benefit | Major benefit | Major benefit |
| Economy - Economic efficiency of the transport system | Moderate negative impact | Moderate negative impact | Moderate negative impact | Moderate negative impact |
| Comparative Access by Geographic Location | Moderate negative impact | Moderate negative impact | Minor negative impact | Minor negative impact |
Environment – Noise and Vibration
When considered “with policy”, noise level changes will range from no benefit or impact to minor beneficial in this option, with a maximum predicted reduction in noise level of 1.5 dBA, for 100% compliance, and 0.6 dBA for realistic compliance, due to changes in average speed and traffic flows.
When considered “without policy”, noise level changes will range from no benefit or impact to minor beneficial in this option, with a maximum predicted reduction in noise level of 1.5 dBA, for 100% compliance, and 0.7 dBA for realistic compliance, due to changes in average speed and traffic flows. The magnitude of changes in noise level evaluated as a comparison between the future appraisals and do-nothing scenarios in the year of assessment.
An overview of the noise assessment is presented in Table 6-9, with further details provided in Appendix C.
| Category appraised | 100% Compliance - Without Policy | 100% Compliance - With Policy | 100% Compliance - Without Policy | 100% Compliance - With Policy |
|---|---|---|---|---|
| Environment - noise impact | 1.5 dB | 1.5 dB | 0.7 dB | 0.6 dB |
Environment – local air quality (airborne matter and Nitrous Oxide emissions)
Option 2 when considered “without policy” and 100% compliance, results in a moderate benefit in road NOx emissions, a minor negative impact in PM10 emissions and no benefit or impact for PM2.5 emissions in 2025 and 2030. For 2045, the assessment predicts a minor benefit for road NOx emissions, a minor negative impact for PM10 emissions and no benefit or impact for PM2.5 emissions.
Option 2 when considered “without policy” for realistic compliance, predicts a minor benefit in road NOx emissions, but no benefit or impact from PM10 and PM2.5 emissions in 2025, 2030 and 2045.
The assessment shows that when considered “with policy”, the 100% compliance future predicts a moderate benefit in road NOx emissions and no benefit or impact for PM10 and PM2.5 emissions. For 2030 the assessment predicts a moderate benefit for NOx emissions, a minor negative impact for PM10 emissions and no benefit or impact for PM2.5 emissions. For 2045, the assessment predicts a minor benefit in road NOx emissions, a minor negative impact for PM10 emissions and no benefit or impact for PM2.5 emissions.
Option 2 for the realistic compliance future predicts a minor benefit in road NOx emissions, but no benefit or impact for the PM10 and PM2.5 emissions in all years.
An overview of the air quality assessment for Option 2 is provided in Table 6-10. The impacts for 2025 and 2045 are presented in Appendix D.
| Category appraised | 100% Compliance - Without Policy | 100% Compliance - With Policy | Realistic Compliance - Without Policy | Realistic Compliance - With Policy |
|---|---|---|---|---|
| Change in NOx emissions (kg/year) | -213,165 | -179,451 | -93,960 | -78,340 |
| Change in PM10 emissions (kg/year) | 12,803 | 10,376 | 4,838 | 3,866 |
| Change in PM2.5 emissions (kg/year) | 3,944 | 3,429 | 1,485 | 1,306 |
Climate Change – Greenhouse Gas Emissions
The various future scenarios considered only show small reductions in greenhouse gas emissions. These savings are slightly increased in the “With policy” futures and with 100% compliance scenarios. An overview of the Greenhouse Gas Emissions assessment is presented in Table 6-11 with further details provided in Appendix E.
| Category appraised | 100% Compliance - Without Policy | 100% Compliance - With Policy | Realistic Compliance - Without Policy | Realistic Compliance - With Policy |
|---|---|---|---|---|
| Total Changes CO2e emissions (tonnes) over 60-year appraisal period following opening (t) | 5,180,019.69 | 4,023,674.17 | 2,379,885.70 | 1,725,009.66 |
| Percentage Change | -4.24% | -1.73% | -0.82% | -0.74% |
Health, Safety and Wellbeing – Accidents (All severity)
All future scenarios under Option 2 show significant reductions in the number of collisions. These impacts are significantly enhanced under the 100% compliance futures. An overview of the envisaged collision savings is presented in Table 6-12, with further details provided in Appendix F.
| Category appraised | 100% Compliance - Without Policy | 100% Compliance - With Policy | Realistic Compliance - Without Policy | Realistic Compliance - With Policy |
|---|---|---|---|---|
| Collision Savings in first year (Core Scenario) |
Fatal - 14 Serious - 52 Slight - 33 Total - 99 |
Fatal - 13 Serious - 49 Slight - 31 Total - 94 |
Fatal - 7 Serious - 25 Slight - 15 Total - 47 |
Fatal - 7 Serious - 23 Slight - 14 Total - 44 |
| Collision savings over 60 year assessment period (Core Scenario) |
Fatal - 817 Serious - 3095 Slight - 1991 Total - 5904 |
Fatal - 591 Serious - 2270 Slight - 1523 Total - 4384 |
Fatal - 418 Serious - 1602 Slight - 985 Total - 3005 |
Fatal - 289 Serious - 1045 Slight - 615 Total - 1949 |
| Collision Savings in first year (Uplift Scenario) |
Fatal - 17 Serious - 52 Slight - 33 Total - 102 |
Fatal - 16 Serious - 49 Slight - 31 Total - 96 |
Fatal - 9 Serious - 25 Slight - 15 Total - 49 |
Fatal - 8 Serious - 23 Slight - 14 Total - 45 |
| Collision savings over 60 year assessment period (Uplift Scenario) |
Fatal - 971 Serious - 3095 Slight - 1991 Total - 6057 |
Fatal - 700 Serious - 2270 Slight - 1523 Total - 4493 |
Fatal - 504 Serious - 1602 Slight - 985 Total - 3091 |
Fatal - 345 Serious - 1045 Slight - 615 Total - 2005 |
Economy – Economic efficiency of the transport system
Option 2 is predicted to result in a large adverse effect for economic efficiency due to the large number of roads across Scotland having speed limits reduced. As expected, this is a slightly lower disbenefit in the without policy future as the lower number of trips means fewer people are impacted.
If 100% compliance with the new speed limits was achieved it would be expected that Option 2 would have a much larger adverse impact - by around three times. However, it would still be considered as large adverse.
An overview of economic assessment is presented in Table 6-13, with further detail of the economic appraisal presented in Appendix G and Appendix I.
| Transport Economic Efficiency (TEE) Benefits | 100% Compliance - Without Policy | 100% Compliance - With Policy | Realistic Compliance - Without Policy | Realistic Compliance - With Policy |
|---|---|---|---|---|
| Consumer - commuting user benefits; Travel Time | -516 | -396 | -217 | -159 |
| Consumer - commuting user benefits; Vehicle operating costs | 82 | 53 | 33 | 24 |
| Consumer - commuting user benefits; Subtotal | -434 | -344 | -184 | -136 |
| Consumer - other user benefits; Travel Time | -470 | -365 | -196 | -145 |
| Consumer - other user benefits; Vehicle operating costs | 92 | 65 | 38 | 26 |
| Consumer - other user benefits; Subtotal | -379 | -300 | -158 | -119 |
| Business benefits; Travel Time | -992 | -1,029 | -386 | -381 |
| Business benefits; Vehicle operating costs | -67 | -56 | -29 | -21 |
| Business benefits; Subtotal | -1,059 | -1,085 | -415 | -402 |
| Total TEE benefit | -1,871 | -1,728 | -757 | -657 |
Comparative Access by Geographic Location
The fisheries industry is a key industry within Scotland and the impacts on these journey times have been assessed to understand the likely impact. These trips have been assessed from key location to nearby the Scotland border at Gretna Green. The realistic compliance results are presented in Table 6-14 below for the PM peak.
| From | To | Do Minimum | Option 2 | Difference |
|---|---|---|---|---|
| Aberdeen | Gretna Green | 04:07:35 | 04:12:47 | 00:05:12 |
| Scrabster | Gretna Green | 06:14:46 | 06:27:10 | 00:12:25 |
| Ullapool | Gretna Green | 05:04:34 | 05:14:40 | 00:10:06 |
| Uig | Gretna Green | 08:25:54 | 08:29:48 | 00:03:54 |
| Oban | Gretna Green | 03:38:49 | 03:42:43 | 00:03:54 |
Table 6-14 above shows the largest increase is seen for the route from Scrabster to Gretna where this is an around 12-minute increase to the current six-hour journey time. Therefore, it is unlikely the long HGV routes will be severely impacted by this option. This is expected to be closer to a 30-minute impact within the 100% compliance scenario which would be a significant impact.
Although the option increases the speed limit of HGV’s on single and dual carriageways, HGV traffic will interact with other vehicles that will have their speed limit reduced.
Other Assessment Considerations
The STAG appraisal process requires consideration of Equality Impact Assessment, Feasibility, Affordability and Public Acceptability and Risk and uncertainty. The appraisal of these are outlined within this section of the report.
Equality Impact Assessment (EQIA)
To comply with the requirements of the Equality Act 2010 (Specific Duties) (Scotland) Regulations 2012, an EQIA of the options has been undertaken.
The assessment shows that both Option 1 and Option 2 will result in an overall slight benefit for some protected characteristic groups, with no negative impact identified This is presented within Appendix H.
Feasibility, affordability and public acceptability
Option Implementation
There are two legal processes available in Scotland to alter speed limits on public roads. These are:
- Implementation Method A - a Parliamentary Act, which could vary the National Speed Limit (for varying vehicle types) across all Scottish roads; and
- Implementation Method B - promotion of Permanent Traffic Regulation Orders (PTROs), which would be processed by each individual local roads authority covering roads in their statutory area.
The PTRO route would require all 32 Local Authorities (as Road Authorities for their specific areas) and Transport Scotland (as Roads Authority for the Scottish Strategic Trunk Road Network) to promote their own individual PTRO and, consequently, would likely be more time intensive. It would also be more costly to promote this and require a significant change to existing speed limit signs across the country as the alterations would be classed as localised speed limits (rather than a change to the National Speed Limit) and would need to be signed accordingly. In addition, the timescales for promotion of these individual Orders may vary (possibly significantly) and therefore the implementation of the lowered speed limits at a national level and the subsequent monitoring of their effects may be problematic. This may be further compounded by the fact that the promotion of some of the PTROs may be unsuccessful as each would be open to public consultation and ultimately determined by Local Authority Committees. The implementation of PTROs by Local Authority Committees may vary in adoption in terms of consistency and timescales. If there is a variation in timescales, this may lead to a safety issue as drivers may be travelling between Local Authorities and encountering varying speed limits.
Promoting PTROs would, however, provide flexibility in applying the new speed limits, allowing this to progress in areas where a PTRO can be promoted relatively quickly while other, more complex, areas are considered further. It may also be viewed as a more transparent route as the promotion of each Order would involve public consultation.
The use of a Parliamentary Act would require the preparation of one document that would be presented to the Scottish Parliament for MSPs to vote upon and therefore would potentially be significantly quicker promote. A successful promotion of the Bill would allow for all speed limits to be changed accordingly across the country, significantly simplifying the practical implementation of these changes, whilst minimising the need to change speed limit signing as the existing National Speed Limit signs would still be valid. It would also allow for more effective monitoring and evaluation of the measures as the alterations could be installed nationally over a relatively short period of time.
This approach, however, does not allow for a more incremental, localised approach that would allow speed limits to be varied in areas where the populace deem this more acceptable. In addition, it would necessitate an education strategy to ensure public awareness of the new National Speed Limits and may be a less popular approach with the public as it does not include direct consultation with them, although it is recognised that it does involve their representatives in Parliament.
Recognising that the legal processes involved with both implementation methods will involve specialist knowledge, it is recommended that competent advice on these legal processes is sought prior to implementation of the options presented in this report.
There are numerous guidance documents used within Scotland for the setting of speed limits and to inform on enforcement and education. The suitability of these guidance documents will require to be reviewed if any of the options considered are implemented.
Analysis of Monetised Costs and Benefits
The Analysis of Monetised Costs and Benefits (AMCB) for Implementation Method A is presented in Table 6-15 and Table 6-16, further detail of the economic assessment is presented in Appendix I. This summarises the monetised impacts of a scheme that are considered sufficiently robust for inclusion in the scheme’s Net Present Value (NPV) and initial Benefit to Cost Ratio (BCR).
The AMCB table combines information from the TEE and Cost tables with monetised estimates of other impacts such as noise, air quality, and accidents. Positive values represent benefits, while negative values represent disbenefits or costs. All values are shown in 2010 prices, discounted to 2010.
Based on the AMCB, the total monetised benefits are positive for Option 1 realistic compliance with policy (£33m PV) and without policy future scenarios (£6m PV) due to the accident savings outweighing the journey time disbenefits. For the rest of the future scenarios disbenefits are forecast with these being greatest for Option 2 100% compliance.
With a Net Present Value (NPV) above zero for Option 1 realistic compliance with policy, it is estimated to achieve benefit to cost ratios (BCR) between 2 and 5.6 depending on the method of implementation. For the comparable without policy scenarios the BCRs range between 0.3 and 1. All other future scenarios are estimated to deliver a negative NPV and negative BCR.
| (£m, 2010 prices and values) | 100% Compliance - Without Policy | 100% Compliance - With Policy | Realistic Compliance -Without Policy | Realistic Compliance - With Policy |
|---|---|---|---|---|
| Noise | 0 | 0 | 0 | 0 |
| Local Air Quality | 0 | 0 | 0 | 0 |
| Greenhouse Gases | 7 | 3 | 4 | 2 |
| Journey Quality | 0 | 0 | 0 | 0 |
| Physical Activity | 0 | 0 | 0 | 0 |
| Accidents | 440 | 329 | 259 | 190 |
| Economic Efficiency: Consumer Users (Commuting) | -106 | -77 | -55 | -39 |
| Economic Efficiency: Consumer Users (Other) | -116 | -91 | -58 | -44 |
| Economic Efficiency: Business Users and Providers | -231 | -219 | -114 | -102 |
| Wider Public Finances (Indirect Taxation Revenues) | -5 | -2 | -3 | -2 |
| Present Value of Benefits | -11 | -58 | 33 | 6 |
| Present Value of Costs National Legislation Change (Implementation Method A) | 6 | 6 | 6 | 6 |
| Present Value of Costs Change existing statutory legislation (TROs) (Implementation Method B) | 16 | 16 | 16 | 16 |
| Net Present Value National Legislation Change (Implementation Method A) | -17 | -64 | 27 | 0 |
| Net Present Value Change existing statutory legislation (TROs) (Implementation Method B) | -27 | -74 | 16 | -11 |
| Initial BCR National Legislation Change (Implementation Method A) | -1.8 | -9.9 | 5.6 | 1.0 |
| Initial BCR Change existing statutory legislation (TROs) (Implementation Method B) | -0.7 | -3.5 | 2.0 | 0.3 |
The BCRs are outlined in Table 6-16 below for Option 2.
| (£m, 2010 prices and values) | 100% Compliance - Without Policy | 100% Compliance - With Policy | Realistic Compliance -Without Policy | Realistic Compliance - With Policy |
|---|---|---|---|---|
| Noise | 0 | 0 | 0 | 0 |
| Local Air Quality | 0 | 0 | 0 | 0 |
| Greenhouse Gases | 95 | 72 | 38 | 30 |
| Journey Quality | 0 | 0 | 0 | 0 |
| Physical Activity | 0 | 0 | 0 | 0 |
| Accidents | 846 | 646 | 433 | 299 |
| Economic Efficiency: Consumer Users (Commuting) | -434 | -344 | -184 | -136 |
| Economic Efficiency: Consumer Users (Other) | -379 | -300 | -158 | -119 |
| Economic Efficiency: Business Users and Providers | -1,059 | -1,085 | -415 | -402 |
| Wider Public Finances (Indirect Taxation Revenues) | -75 | -59 | -30 | -25 |
| Present Value of Benefits | -1,005 | -1,069 | -316 | -352 |
| Present Value of Costs National Legislation Change (Implementation Method A) | 6 | 6 | 6 | 6 |
| Present Value of Costs Change existing statutory legislation (TROs) (Implementation Method B) | 16 | 16 | 16 | 16 |
| Net Present Value National Legislation Change (Implementation Method A) | -1,011 | -1,075 | -322 | -358 |
| Net Present Value Change existing statutory legislation (TROs) (Implementation Method B) | -1,021 | -1,085 | -333 | -369 |
| Initial BCR National Legislation Change (Implementation Method A) | -169.7 | -180.5 | -53.4 | -59.5 |
| Initial BCR Change existing statutory legislation (TROs) (Implementation Method B) | -61.1 | -65.0 | -19.2 | -21.4 |
Risks and uncertainty
A risk and uncertainties assessment has been undertaken. The key findings of this are presented in Appendix K. Given the nature of the options and different future scenarios modelled within TMfS, there are a number of the risks and uncertainties that are the same across the options and future scenarios considered.
Option 2 proposes reducing speed limits on dual carriageway and motorways which are generally perceived by the public as being the safest roads designed to accommodate higher speeds. This may increase promotability and public acceptability risks in comparison with Option 1.
Scottish Trunk Road Infrastructure Project Evaluation (STRIPE)
Being able to demonstrate the impacts of an implemented option which involves public funding is essential to ensure accountability. STRIPE is a recognised framework for the evaluation of road schemes costing over five million pounds and considers the following core questions:
- Were the scheme’s Transport Planning Objectives achieved and benefits realised?
- Were the outturn impacts of the project as forecast?
- How well was the project implemented?
- What were the impacts on established policy directives?
- What lessons can we learn to improve decision making?
A STRIPE plan will be developed that outlines the proposed evaluation strategy that will inform requirements regarding baseline data.