Hi Everyone,
Welcome to the fifth post in my conference and journal paper post series. This series will contain ten conference and journal papers from my time working in the Queensland Government. In my post, My Peer Reviewed Conference and Journal Papers, I explain the purpose of this series.
In 2012, I led a team of several economists who conducted rapid cost benefit analyses for the projects in the Bruce Highway Action Plan (BHAP); dozens of projects along the Bruce Highway bundled together like a program of works for the purpose of funding. I was not the most senior economist in the group, but I had the most knowledge in regards to evaluating programs as well as rapid analysis. This created a slightly strange dynamic, but it worked quite well. As I led the group, I could make use of the methodologies I had worked on for my papers from previous years. These papers included the Road Program Evaluation: Assessing the Bigger Picture and Advanced Methods of Evaluating Benefits from Improved Flood Immunity in Queensland.
Working on BHAP was a difficult task. It involved many different project teams from different districts. There were various different teams working on the project/program management, engineering aspects, and estimating of costs. Information kept changing or being reorganised, which made it incredibly difficult to conduct the cost benefit analyses. We were also under incredibly short deadlines. If it was not for the rapid analysis cost benefit analysis model. It would have been a complete failure. As it was, it was incredibly messy, but we did obtain results for almost all the BHAP projects. We even produced a final report. However, it lacked detail and did not adequately cover the failings of the program of works as a whole. This was especially true in regard to safety. Fast-forward to 2024, the number of fatal accidents along the Bruce Highway is at record highs (The North West Star). If more time had been given to the analysis and the report, the problems could have been more clearly highlighted. The projects could have been reprioritised, and the safety of the highway could have been improved.
In 2013, presented the paper Program Evaluation: An Applied Case Study at the Australasian Transport Research Forum (ATRF). This was the second paper I wrote for this conference. The paper broke down the various methodologies used to evaluate a wide range of projects that were included in the Bruce Highway Action Plan. The paper referred to the methods I described in my other papers. The paper also described the rapid analysis model, which was used to conduct the rapid cost benefit analyses in a fraction of the time a full model would have taken. The paper made no mention of the many problems and shortcomings of the BHAP process.
This paper underwent considerable scrutiny from my directors at Transport and Main Roads. They did not want me to present this paper. They considered the results of the cost benefit analysis as an attack on the Government. We eventually reached a compromise, which involved me removing all the names of the projects. The program and each project were designated letters and numbers. This made the paper look a little ridiculous, but it still allowed me to discuss the methodology. The paper was still accepted by the ATRF.
Two years later, I approached the Journal of Civil Engineering and Architecture. I offered them the paper with the actual names of the projects. They accepted and published the paper a few months later. I have included this paper in this post.
Transport and Main Roads may describe the paper as controversial, but there is nothing controversial in it. It just covers the methodology used in the analysis. Ex-post evaluations of the BHAP cost benefit analyses would be very interesting and would reveal much deeper problems. Unfortunately, I am in no position to conduct one.
The Bruce Highway Action Plan Program Evaluation
Abstract
The Bruce Highway Action Plan (BHAP) Program Evaluation was a momentous task conducted in most part by the Transport and Main Roads (TMR) Cost Benefit Analysis (CBA) Team. The evaluation included 189 overtaking lanes, 404kms of road widening and shoulder sealing in various places between Brisbane and Cairns, 56 capacity focused projects and 16 flood immunity focused projects. The total projected capital costs of all projects proposed as part of the BHAP amounted to over Sixteen Billion Dollars. The program evaluation conducted, due to the short timeframes, lack of available data and strategic nature of the plan, has been ‘coined’ a strategic evaluation.
This paper focuses on the methodology applied to the projects proposed in the BHAP. A TMR designed project/program evaluation model (CARP V1.0) was used to evaluate the majority of the proposed BHAP projects. The model produces streams of discounted benefits and costs of the projects and program using limited and incomplete data. The large scale of work and the close proximity of projects allowed for an integrated approach to the analysis, which considered the impact projects have on each other.
The result of the program if all evaluated projects are included is a benefit cost ratio (BCR) of approximately 0.71 at a discount rate of 7%. If the less viable projects are removed from the program, the program can obtain a benefit cost ratio of greater than one with a sufficiently large number of projects remaining.
Acknowledgements
I would like to thank my colleagues: Mark Best, Mathew Singh, Shane Campbell, Alison Kent, Michael Ahlberg and Robin Murray for the many hours of dedicated hard work that they put into completing the BHAP Program Evaluation.
1. Introduction
The Bruce Highway Action Plan (BHAP) is an engineering based needs assessment that aims over a ten-year period to address capacity, flooding and safety problems along the entire 1677km length of the Bruce Highway from Brisbane to Cairns1 [1]. The BHAP proposes over sixteen billion dollars worth of improvements to the Bruce Highway over the next ten years [1]. The projects proposed as part of the BHAP include road widening and shoulder seals, overtaking lanes, bypasses and ring roads, lane duplications, raised bridges and approaches, road realignments, intersection upgrades and minor safety treatments [2]. The poor safety record, frequent flooding and high traffic growth rates are the major impetuses for the BHAP [1].
The Transport and Main Roads (TMR) Cost Benefit Analysis (CBA) Team was given the task to evaluate and provide economic advice regarding the initial viability and prioritisation of the initial projects to be proposed as part of the BHAP. The BHAP program evaluation consists of projects to be funded under the Nation Building Program 1 (NBP1), Nation Building 2 Program (NB2) and BHAP2 . As part of the BHAP, all proposed projects require CBAs. Projects to be funded under NBP1 had already undergone CBAs; these projects due to the application of different methodologies have not been combined with the NB2 and BHAP projects. The focus of this paper is the evaluation of projects to be funded as part of NB2 and BHAP.
The BHAP program evaluation was intended as a strategic quantitative evaluation of all projects proposed to be constructed along the Bruce Highway in both the short run and long run. There was an intended timeframe of approximately 3 months from July 2012 to early October 2012 to complete the evaluation of the projects. Given many of the projects were in the early planning stages, complete information about the scope or data was not available. Considering the short timeframe and limited data and scope of projects, a rapid approach to evaluation had to be devised to complete the task.
2. The Application of Concise Analysis of Road Programs (CARP) Model
CBA6.1 is the prescribed model used to evaluate road projects in TMR. CBA6.1 enables a detailed evaluation of a wide range of projects and provides a wide range of flexibility in regards to traffic growth, traffic composition and road treatments that influence road conditions over the life of the project. Unfortunately, because of the lack of data, many of the data fields required by CBA6.1 to calculate results could not be populated rendering evaluations incomplete. CBA6.1 is designed for project evaluation rather than program evaluation and lacks the flexibility to combine large numbers of projects without the help of specially designed spreadsheets. Given the above-mentioned limitations and the tight timeframes, CBA6.1 was deemed not the most suitable model for the job. Instead, another model, CARP (V1.0), developed in early 2012 was used as the primary model to evaluate the NB2 and BHAP funded projects, CARP (V1.0) was designed to rapidly evaluate programs or packages of projects with minimal comprise to the accuracy of the evaluation.
Literature suggests that there are a number of advantages of evaluating projects as a program of works. Such advantages include the recognition and evaluation of benefits of interdependent projects (Nemhauser and Ullmann, [3], Gear and Cowie, [4], Fox et al, [5] and Tao and Schonfeld, [6]), improved transparency of project ranking and options analysis, clear identification of the net gains of a program and improved rigour of analysis [7]. CARP is designed to capture all of the above-mentioned benefits of program evaluation as well as provide the flexibility to evaluate projects individually.
CARP reduces time spent on collecting data by reducing the data requirements of each project. The project data that often require more time to acquire or are not normally available are generally not required in CARP. Project parameters requiring data for CARP are parameters with the highest sensitivity to road user cost (RUC) calculations. Parameters that RUC are most sensitive to are section length, average annual daily traffic (AADT), model road states (MRS)3 , traffic growth rates, road alignments and traffic breakdown [8]. Of the above-mentioned parameters, only traffic breakdown has been slightly compromised as the eight vehicle types used in CBA6.1 are reduced to just two vehicle types (cars and heavy vehicles). This compromise is small as traffic data for all eight vehicle types is rarely available, thus requiring assumptions to be made of that breakdown. Other data requirement omissions include surface and pavement types (all pavements are assumed to be sprayed seal), detailed maintenance schedules, flexible annual traffic growth rates and annual adjustments to roughness. The impact of excluding these parameters in most cases is minimal and in the case of most of the NB2 and BHAP funded projects, exact data was often not available. For models capable of providing detailed evaluation, such as CBA6.1, the above-mentioned parameters would be based on the best estimates of the analyst, which may not necessarily be consistent across all projects evaluated.
3. Project Evaluation Methodology
The project evaluation methodology applied to CARP to calculate RUC is consistent with Austroads and TMR CBA tool (CBA6). Austroads AP-R264/05 harmonisation paper [9] is the source for the vehicle operating cost and travel time cost algorithms applied to CARP. Accident cost algorithms are sourced from Austroads AP-R184 [10], Road Transport Authority (RTA) [11], TMR and Austroads Part 4: Guide to Project Evaluation [12]. Emission cost unit values per tonne of fuel consumed and the externality costs per vehicle travelled are sourced from Austroads Part 4: Guide to Project Evaluation [12].
The economic measures/indicators produced by CARP are the benefit cost ratio (BCR), net benefit investment ratio (NBIR), net present value (NPV) and internal rate of return (IRR). The BCR is calculated according to the formula stated in Austroads [13] and the NBIR is calculated according to the Australian Transport Council [14] BCR formula, quoted as ‘NBIR’ as stated by Campbell and Brown [15]. The application of discount rates to projects is flexible and users of CARP have an option to sensitivity test options with a range of discount rates. CARP also incorporates sensitivity testing around calculated benefits and costs to provide a maximum and minimum BCR or NBIR. Table 1 provides a summary of the methodologies applied to calculate each RUC savings.
Table 1: Summary of Methodology Applied in CARP
Methodology Applied (Benefits) Applied to Base and Project Case
| Travel Time Cost Savings | (Distance × Unit Value/Operating Speed) × AADT × 365.25 (Operating speed is calculated using freespeed arrays adjusted for horizontal, vertical alignment, sign posted speed and congestion).
| Vehicle Operating Cost Savings | Fuel + Oil + Tyre Wear + Maintenance & Repair + Interest & Depreciation (incorporates horizontal & vertical alignment factors, distance and operating speed, refer to CBA6 manual, excludes lookup values for congestion impacts on vehicle operating costs (VOC)).
| Accident Cost Savings | Accident costs calculated based on MRS accident rates adjusted for horizontal alignment and Austroads unit values for accidents adjusted for operating speed.
| Accident Cost Savings from Intersection & Minor Road Treatments | Accidents for projects with minor safety treatments and intersection upgrades are identified according to the definition of classification of accidents (DCA) codes. Treatment reductions are based on the RTA Accident Reduction Guide and Austroads Unit values for Road User Movements (RUM) [11].
| Road Closure Cost Savings | Road closure savings consist of reduced waiting (same methodology as travel time costs (TTC) but based on average duration of closure (ADC) and average annual time of closure (AATOC) instead of 365.25 days, costs of diverting (reduced VOC + TTC + Accident) and not travelling costs (Reduced costs of not reaching destination calculated as loss of consumer surplus).
| Emission Cost Savings | Emissions derived based on fuel consumed derived according to AP-R264/05 Methodology multiplied by Austroads costs of emissions (includes CO2, CO, NOX and SO2).
| Other Externalities | Externalities calculated per change in vehicle kilometres travelled (VKT) multiplied by Austroads unit costs for externalities.
| Generated Traffic Benefits | Calculated as the gain in consumer surplus of generated traffic also known as rule of half (perceived road user cost savings per existing road user × generated road users / 2 [8].
| Other Benefits | Benefits not calculated in CARP but manually entered by user.
| Unit Values and Algorithmsgenerally applied to benefits calculated
| Unit Values | Unit Values are provided by Austroads publication - Part 4: Project Evaluation Data (Updated Road User Effects Unit Values), 2012 Version [12], all unit values are updated using the latest CPI.
| Algorithms | Algorithms are provided by Austroads publication - AP-R264/05 [9].
| Methodology Applied (Costs) |
| Net Construction/Capital Costs | Project Case Capital Cost - Base Case Alternative Cost (P50 without escalation).
| Net Increase in Operating Costs | Annual Project Case Operating Costs - Annual Base Case Operating Costs multiplied by evaluation period. |
4. Program Evaluation MethodologyThe program evaluation methodology should ideally be applied in two stages. The first stage involves the analysis of options to determine the optimal project option to be included in the program. The incremental benefit cost ratio (IBCR) or the incremental net benefit investment ratio (INBIR) are compared with the program cut-off BCR/NBIR to determine the optimal option to be included in the program. The second stage involves the ranking of projects according to BCR or NBIR, until the allocated budget is reached or the cut-off BCR/NBIR has been reached. The sequential and simultaneous approaches outlined in Davies [7] can be applied to the program evaluation using CARP. The sequential approach is based on the assumption that projects have been ranked prior to the evaluation; projects are evaluated in order of ranking. If the sequential approach is applied, the user of CARP can choose to select a predetermined ranking4 rather than the BCR or NBIR5 . The simultaneous approach is based on the assumption that all projects in the program will proceed in the project case and none of the projects will proceed in the base case. Timing of projects is not considered in the simultaneous approach. For BHAP, the simultaneous approach was deemed most appropriate as the ranking of projects was yet to be finalised and project timings were unavailable. Using the simultaneous approach, the results of the program evaluation could be used as an input to project ranking within the program. All projects evaluated as part of the BHAP using the CARP model were subject to a number of general assumptions; these assumptions are as follows. • Evaluation period is 31 years (1 year of construction and 30 years of benefits). 4.1. Methodology Applied to Flood Immunity ProjectsThe data provided for most of the flood immunity projects were limited to project costs, annual average time of closure (AATOC), maximum time of closure (Q50 flood events), road ID and chainage of the location of the project. The chainage and road ID was used to acquire road and traffic data from Chartview7 . Even with the acquisition of data from Chartview, a number of parameters such as the length and road characteristics of the diversion routes and nature of road closures remained unknown. For each project, two types of road closures were assumed, Q508 for serious flood events and Q2 for local flood events. For Q50 floods, maximum time of closure is assumed to equal the average duration of closure (ADC) and the AATOC is assumed to equal ADC/50. For local flood events, AATOC equals the AATOC provided minus the AATOC of the Q50 flood and the ADC equals AATOC multiplied by two. Yeppen South Floodplain project (F13) was evaluated over three flood periods due to the availability of additional data. Google maps was used to identify diversion routes during local flood events and no diversion routes were assumed available during Q50 flood events. The road characteristics of the diversion routes were held constant at a lower standard than that of the Bruce Highway. Road user behaviour has not been specified for any of the flood immunity projects, therefore, the assumption that road users opt for the least cost approach to reach a destination has been applied which is consistent with flooding methodology described in Davies [16]. The flood immunity program of works has been evaluated based on the assumption that all projects will be constructed in the project case and no projects will be constructed in the base case. This method is appropriate for the initial evaluation of projects to determine a ranking based on BCR. To assess the impact of potential interrelatedness between projects, projects within close proximity of each other have been re-evaluated based on the assumption that not all interrelated projects are constructed in the project case. This approach has been adopted for Ingham to Cardwell Range Upgrade (F4) and Cattle and Francis Creek Upgrade (F5), and Brandon – Sandy Corner Upgrade, Burdekin River Upgrade and South of Home Hill Flood Immunity Upgrade. Stage 1 of the Burdekin Deviation (F8) is a possible alternative to the South of Home Hill Flood Immunity Upgrade and Burdekin Bridge Existing Upgrade. Stage 2 of the Burdekin Deviation (F8) is a possible alternative to the proposed Brandon – Sandy Corner Upgrade and Burdekin River Upgrade to improve flood immunity while also allowing through traffic to bypass Ayr. The methodology applied to the Burdekin projects/options is explained in more detail in Section 4.4.1. See Davies [7] for more information on program evaluation approaches for interrelated projects. 4.2. Assumptions Applied to the Flood Immunity ProjectsGiven the limited availability of data, a number of assumptions have been made and applied consistently across all flood immunity projects. • Assets of a life of 100 years (mostly bridges) are apportioned 20% of capital costs. 4.3. Results of the Flood Immunity ProjectsTiaro Bypass is the only flood immunity project with a NPV greater than zero and a BCR greater than one. To maximise the NPV of the program, the Tiaro Bypass should be the only project to be included in the program. A number of other projects with BCRs below one could be included in the program without pulling the overall NPV of the program below zero. Table 2 contains the projects proposed to be included in the program based on the strategic economic analysis described in this report. The Burdekin Deviation (F8) described in the Burdekin Deviation options analysis section of the methodology documentation is also included in the results in Table 2. See Appendix A for the NPV and BCR for all projects proposed in the BHAP flood immunity program. For the sensitivity analysis, benefits of all projects are subject to a sensitivity of plus or minus 50% due to lack of data. Costs are subject to a sensitivity of plus or minus 20%, which is a standard sensitivity test for most evaluations conducted by TMR. The difference between the minimum and maximum BCRs for most projects in Table 2 is quite large. A minimum BCR of greater than one even at this strategic level indicates a project is definitely viable. A maximum BCR of greater than one indicates a project may become economically viable if improved or more detailed data is used. A maximum BCR of less than one indicates the project is highly unlikely to become economically viable even with improved data, these projects may be included in a program if they indirectly contribute to the value of the program as a whole. Table 2: Results of Program by Project (Recommended Projects)10Source: TMR [2] 4.4. Methodology Applied to Capacity ProjectsFor the flood immunity projects, a standard methodology could easily be applied across all projects but for the capacity projects, such a methodology was not possible as the projects varied considerably in nature. Therefore, the methodologies of only a few select projects have been included in this paper. The selected projects demonstrate the interrelated nature of projects that are within close proximity to each other. The BCR and NPV of the capacity projects are included in Appendix A. 4.4.1. Burdekin Deviation MethodologyThe Burdekin Bridge, located along the Bruce Highway near Home Hill and Ayr, has height and width restrictions that prevent some of the heavy vehicles from crossing the Burdekin River. These heavy vehicles are forced to permanently divert to cross the Burdekin River at an alternative location. Heavy vehicles that cannot cross the Burdekin Bridge travelling between Mackay and Townsville are assumed to travel an extra 252km to avoid the Burdekin Bridge. Two alternatives have been proposed to resolve this problem; construct a new bridge and approaches (Stage 1 of the Burdekin Deviation) or upgrade the existing bridge. Flooding occurs at Plantation Creek, Sheep Station Creek and South of Home. Brandon – Sandy Corner, Burdekin River Upgrades, and South of Home flood immunity project or Stage 1 of the Burdekin Deviation will improve the flood immunity of the Bruce Highway for all road users. Alternatively, Stage 2 of the Burdekin Deviation will improve the flood immunity of the Bruce Highway, benefiting through traffic more than local traffic. Stage 2 of the Burdekin Deviation provides additional benefits by allowing through traffic to bypass Ayr. Stage 1 of the Burdekin Deviation will resolve the partial road closure to 10% of the heavy vehicles passing through Ayr (vehicles that do not meet the existing bridge specifications). In the base case, cars and 90% of the heavy vehicles cross the existing bridge, while 10% of the heavy vehicles travel an extra 252km to cross the Burdekin River. Stage 2 of the Burdekin Deviation has been treated as a bypass that improves flood immunity and capacity. All other assumptions applied to other flood immunity projects holds true for the bypass. The bypass also includes railway crossings, the benefits of these crossing have been excluded from the analysis due to lack of crash related data. The above treatments have been bundled into nine project options, these options are as follows:
4.4.2. Cooroy to Curra (Section A)Cooroy to Curra (Section A), located approximately 20km-30km south of Gympie [17], has been evaluated as a simple duplication from a two-lane highway to a four-lane highway section of road. Increased capacity results in benefits to travel time and reductions in vehicle operating costs. The additional capacity and cost reductions in travel is assumed to generate traffic. A capacity constraint has been applied to the base case; this capacity constraint will prevent the traffic volume from exceeding the capacity of the road. The project case has a larger capacity than the base case; therefore, traffic volume in the project case will exceed that of the base case. The additional traffic is treated as generated traffic. 4.4.3. Cooroy to Curra (Section C)Cooroy to Curra (Section C), located approximately 10km-20km south of Gympie [17], has been treated as a duplication and realignment of the Bruce Highway that also improves flood immunity. This project is subject to the same assumptions as the flood immunity projects; see Section 4.1 for flood immunity methodology and Section 4.2 for assumptions applied to the flood immunity projects. If Section D is not constructed the flood immunity benefits for Section C are removed from the evaluation; see Appendix A for both sets of results. The methodology applied to the duplication of Section C is similar to the methodology proposed for Section A, but also includes a reduction in section length and a change in a curvy horizontal alignment to a straight horizontal alignment. The improved alignment will enable higher operating speeds, reduced tyre wear and fuel consumption, and improved safety. The reduction in section length will reduce road user costs proportionate to the percentage reduction in section length. 4.4.4. Cooroy to Curra (Section D)Cooroy to Curra (Section D), located through Gympie and up to 20km north of Gympie [17], has been evaluated as a realignment and duplication of the Bruce Highway. The project also includes flood immunity benefits similar in nature to Section C. These flood immunity benefits were excluded to avoid double counting, as both Section C and Section D are required to be upgraded to improve the flood immunity of the link through Gympie. 4.4.5. Wide Bay Highway InterchangeThe proposed Wide Bay Highway T-intersection upgrade, located 12km north of Gympie [18], has been evaluated as the replacement of the current at-grade intersection with an overpass to enable traffic turning onto the Bruce Highway from the Wide Bay Highway to move freely. The Wide Bay Interchange has been evaluated twice, one evaluation is subject to the assumption that Section D of the Cooroy to Curra Upgrade proceeds while the other evaluation is subject to the assumption that this Cooroy to Curra (Section D) does not proceed. The construction of Cooroy to Curra (Section D) will improve the base case, as the traffic along the Bruce Highway will be substantially reduced thus reducing delays to vehicles turning right onto the Bruce Highway. Safety benefits for the entire intersection have been evaluated using definition of classification of accidents (DCA) codes. Treatments and the travel time cost and vehicle operating cost savings have been evaluated for vehicles turning onto the Bruce Highway (AADT against gazettal). Distance travelled through the intersection has been halved in the project case as a proxy to simulate delays and vehicle operating costs accrued by vehicles waiting at the intersection. Delays have also been reduced by 25% in the base case if Cooroy to Curra (Section D) proceeds to simulate the impact of reduced traffic volumes along the Bruce Highway (Old). 4.4.6. Boundary Road Interchange UpgradeThe Boundary Road Interchange, located at the interchange of Boundary Road and the Bruce Highway south of Burpengary and 10km north of Pine River [19], requires upgrading to accommodate the increasing traffic flows from local communities and facilitate the implementation of the Managed Motorways’ upgrade described in Section 4.4.7. This project has been evaluated using SIDRA11 data and accident data collected at the project site. The SIDRA data was used to determine peak traffic volume, average travel time for peak periods, average operating speed and average distance travelled through the intersection12 . Average distance travelled was adjusted in the project case based on travel time and used as a proxy to determine travel time costs and vehicle operating costs (VOC). Average distance was chosen over average speed as a proxy as distance has a simple multiplicative relationship to cost calculation, whereas speed influences both VOC and accident cost calculations in CARP. Average speed reductions in the base case are due to start-stop rather than a constant speed, therefore would artificially distort accident cost calculations. The treatment of engineering standard grade separation was applied to evaluate accident cost savings using DCA code accident reduction factors. 4.4.7. Managed Motorways – Gateway Motorway‘Managed Motorways’ is the term used to describe urban motorways that have intelligent information [20]. The proposed Intelligent Transport System (ITS)13 is expected to increase capacity of the Bruce Highway by up to 25% during peak periods [20]. The Bruce Highway (Road ID: 10A) from chainage 0km to 23km has a MRS of 22 (3 lanes in either direction). To simulate an increase in capacity of 25%, the MRS of the project case has been assumed to be increased to 23 (4 lanes in either direction). All other road characteristics are assumed unchanged. In order for the ITS to be implemented, Boundary Road Interchange requires upgrading as described in Section 4.4.6. The Anzac Avenue upgrade, though not evaluated as part of BHAP due to undefined scope, also requires upgrading for the full benefits of ITS to be realised. The costs and benefits of Boundary Road Interchange upgrade have been included in this analysis, whereas cost and benefits from the Anzac Avenue project have been excluded. 4.4.8. Results of the Capacity ProjectsThe results of the capacity projects was mixed with some projects obtaining high BCRs ─ such as Managed Motorways (Gateway Motorway) and Mackay Ring Road Stage 1 ─ while other projects obtained low BCRs ─ such as Bowen Intersection Upgrade and Cairns Southern Access Corridor (SAC) Stage 3. AADT, volume capacity ratio (VCR), traffic growth rate and capital cost were the key factors in determining the NPV and BCR of most capacity projects. Section 6 highlights some other factors that may have distorted results. The capacity projects have been subject to the same sensitivity tests as the flood immunity projects described in the Section 4.2. The complete results of the capacity projects are included in Table 9 in Appendix A. 4.5. Methodology Applied to Safety ProjectsThe safety projects were separated into overtaking lane projects, and road widening and shoulder seal projects. The methodologies applied to the overtaking lane projects vary considerably from road widening and shoulder seal projects. Overtaking lane projects are more complicated to evaluate as they not only improve safety but also travel time. Overtaking lanes also influence upstream14 and downstream areas15 of approximately 3km and 5km respectively. The overtaking lane is expected to improve safety in the upstream area as faster vehicles will wait to safely overtake using the overtaking lane. The overtaking lane will improve operating speed and safety in the downstream area as faster vehicles would have passed slower vehicles using the overtaking lane and are not expected to encounter more heavy vehicles for an average distance of 5km. The road widening and shoulder seal projects are almost entirely focused on improving safety with limited impact on other benefit categories. The road widening and shoulder seal projects as part of BHAP were not clearly defined as projects but rather the upgrade of any sections of the Bruce Highway not currently at the vision width (10m seal). 4.5.1. Overtaking Lane ProjectsOne hundred and eighty-nine overtaking lane projects have been proposed as part of the BHAP. The short timeframes and the insufficient information to the exact location of each overtaking lane prompted the use of a link evaluation approach rather than the evaluation of each individual overtaking lane. Ten links were identified between Gympie and Cairns. The total proposed lengths of the overtaking lanes, downstream and upstream areas per link were combined into one evaluation. The vision distance between overtaking lanes was determined based on the average AADT per link. The overtaking lanes are spaced according to the AADT on the Highway. If the AADT is between 2000 and 4000, the overtaking lanes are spaced 20km apart, if the AADT is between 4000 and 6000, the overtaking lanes are spaced 10km apart and if AADT is greater than 6000 the overtaking lanes are spaced 5km apart. The overtaking lanes have an assumed section length of 1.2km and have upstream areas of 3km and downstream areas of 5km. For sections with AADT of greater than 6000 vehicles, we assume there are no upstream benefits and downstream benefits are reduced to 3.8km. The parameters of the road and traffic data applied to each link are weighted averages for the whole link. The results for each link are given Table 3. Table 3: Results of the Overtaking Lane Link Evaluations
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