Dynamic Traffic Assignment (DTA) is gaining wider acceptance among agencies and practitioners because it serves as a more realistic representation of real-world traffic phenomena than static traffic assignment. Many metropolitan planning organizations and transportation departments are beginning to utilize DTA to predict traffic flows within their networks when conducting traffic analysis or evaluating management measures. To analyze DTA-based optimization applications, it is critical to obtain the dual (or gradient) information as dual information can typically be employed as a search direction in algorithmic design. However, very limited number of approaches can be used to estimate network-wide dual information while maintaining the potential to scale. This dissertation investigates the theoretical/practical aspects of DTA-based dual approximation techniques and explores DTA applications in the context of various transportation models, such as transportation network design, off-line DTA capacity calibration and dynamic congestion pricing. Each of the later entities is formulated as bi-level programs. Transportation Network Design Problem (NDP) aims to determine the optimal network expansion policy under a given budget constraint. NDP is bi-level by nature and can be considered a static case of a Stackelberg game, in which transportation planners (leaders) attempt to optimize the overall transportation system while road users (followers) attempt to achieve their own maximal benefit. The first part of this dissertation attempts to study NDP by combining a decomposition-based algorithmic structure with dual variable approximation techniques derived from linear programming theory. One of the critical elements in considering any real-time traffic management strategy requires assessing network traffic dynamics. Traffic is inherently dynamic, since it features congestion patterns that evolve over time and queues that form and dissipate over a planning horizon. It is therefore imperative to calibrate the DTA model such that it can accurately reproduce field observations and avoid erroneous flow predictions when evaluating traffic management strategies. Satisfactory calibration of the DTA model is an onerous task due to the large number of variables that can be modified and the intensive computational resources required. In this dissertation, the off-line DTA capacity calibration problem is studied in an attempt to devise a systematic approach for effective model calibration. Congestion pricing has increasingly been seen as a powerful tool for both managing congestion and generating revenue for infrastructure maintenance and sustainable development. By carefully levying tolls on roadways, a more efficient and optimal network flow pattern can be generated. Furthermore, congestion pricing acts as an effective travel demand management strategy that reduces peak period vehicle trips by encouraging people to shift to more efficient modes such as transit. Recently, with the increase in the number of highway Build-Operate-Transfer (B-O-T) projects, tolling has been interpreted as an effective way to generate revenue to offset the construction and maintenance costs of infrastructure. To maximize the benefits of congestion pricing, a careful analysis based on dynamic traffic conditions has to be conducted before determining tolls, since sub-optimal tolls can significantly worsen the system performance. Combining a network-wide time-varying toll analysis together with an efficient solution-building approach will be one of the main contributions of this dissertation. The problems mentioned above are typically framed as bi-level programs, which pose considerable challenges in theory and as well as in application. Due to the non-convex solution space and inherent NP-complete complexity, a majority of recent research efforts have focused on tackling bi-level programs using meta-heuristics. These approaches allow for the efficient exploration of complex solution spaces and the identification of potential global optima. Accordingly, this dissertation also attempts to present and compare several meta-heuristics through extensive numerical experiments to determine the most effective and efficient meta-heuristic, as a means of better investigating realistic network scenarios. / text

In the US transportation system, environmental justice (EJ) issues are regulated by a variety of laws to ensure that all have fair treatment with respect to implementation of policies. If State Departments of Transportation adhere to all regulations properly but unconsciously, then an underlying negative impact on a community may still exist as a result of a newly implemented project. Since the implementation of High Occupancy Toll (HOT) lanes are fairly new, and since there have been numerous concerns from the public about their discriminatory nature, a decision support system is needed to identify potential EJ violations and issues when implementing a new or converted HOT lane. No prior model exists. The goal of this research is to assist state's Department of Transportation (DOT) in the early stages of the development of an HOT lane by developing a Potential Environmental Justice Violation Model that will help state agencies predict potential EJ violations before additional resources are invested into a project. By developing a model, this study identifies and classifies characteristic drivers of potential EJ violations related to communities' economic, social, or health and safety status. The Potential Environmental Justice Violation Model (PEJVM) allows state DOTs employees to define and evaluate the distribution of impacts in the relevant categories. The model provides a method for transforming complex qualitative and quantitative data about a project into a user-friendly format where the results can then be visualized using a spider radar diagram to determine the level of impact of each identified variable. The PEJVM was validated using two previous anonymous HOT case studies and demonstrated using the Interstate 85 Case Study in Atlanta, Georgia. This model offers a uniform method of identifying potential environmental justice violations when implementing a HOT lane. The model will also help inform state agencies of potential violations early in the planning stages of HOT lane projects so that the agency can solve any potential EJ issues before additional resources are invested.

Build-Operate-Transfer (BOT) is a form of Public-Private Partnerships that is commonly used to close the growing gap between the cost of developing and modernizing transportation infrastructure systems and the financial resources available to governments. When assessing the feasibility of a BOT project, private investors consider revenue risk - which is stemmed from the uncertainty about future traffic demand - as a critical factor. A potential approach to mitigating the revenue risk is the offering of revenue risk sharing mechanisms such as Minimum Revenue Guarantee options by the government. In addition to Minimum Revenue Guarantee options, a mechanism known as Traffic Revenue Cap options may also be negotiated, which makes the government entitled to a share of revenue when it grows beyond a specified threshold. Financial valuation of investments in BOT projects should take into account uncertainty about future traffic demand, as well as Minimum Revenue Guarantee and Traffic Revenue Cap options. The conventional valuation methods including Net Present Value (NPV) analysis are not capable of integrating the uncertainty about future traffic demand in the valuation of BOT projects and properly pricing Minimum Revenue Guarantee and Traffic Revenue Cap options. Real options analysis can be used as an alternative approach to valuation of investments in transportation projects under uncertainties. However, the appropriate application of real options analysis to valuation of investments in transportation projects is conditioned upon overcoming specific theoretical challenges. Current real options models do not provide a systematic method for estimating the project volatility, which measures the variability of investment value. Existing models do not provide a method for calculating the market value of Minimum Revenue Guarantee and Traffic Revenue Cap options. Also, current models are not able to characterize the impact of Minimum Revenue Guarantee and Traffic Revenue Cap options on private investors' financial risk profile. The overarching objective of this research is to apply the real options theory in order to price Minimum Revenue Guarantee and Traffic Revenue Cap options under the uncertainty about future traffic demand. To achieve this objective, a real options model is created that characterizes the long-term traffic demand uncertainty in BOT projects and determines investors' financial risk profile under uncertainty about future traffic demand. This model presents a novel method for estimating the project volatility for real options analysis. This model devises a market-based option pricing approach to determine the correct value of Minimum Revenue Guarantee and Traffic Revenue Cap options. An appropriate procedure is created for characterizing the impact of Minimum Revenue Guarantee and Traffic Revenue Cap options on the investors' financial risk profile. The proposed real options model is applied to a BOT project to illustrate the valuation process. The limitations of the proposed real options model, as well as the barriers to its implementation, are identified and recommendations for future research are offered. This research contributes to the state of knowledge by presenting a new method for estimating the project volatility, which is required for the real options analysis of transportation investments. It also introduces a risk-neutral valuation method for pricing the market value of Minimum Revenue Guarantee and Traffic Revenue Cap options in BOT projects. The research also contributes to the state of practice by introducing a novel class of assessment tools for decision makers that characterize the investors' financial risk profile under uncertainty about future traffic demand. Proper methods for pricing of Minimum Revenue Guarantee and Traffic Revenue Cap options are useful to public and private investors, in order to avoid wasting capital in transportation projects.

High Occupancy Toll (HOT) lanes were recently proposed for I-85 in Atlanta as a way to relieve congestion and provide a reliable commute time for single occupant drivers that are willing to pay a toll. It is important to evaluate the air quality impacts of such a proposal to meet environmental regulations, such as the National Environmental Policy Act (NEPA) and Transportation Conformity Regulations. The goal of this study is to understand how vehicle mass emissions change as a result of implementing HOT lanes on I-85 in Atlanta . This is done by considering a number of factors affect mass vehicle emissions, such as vehicle activity, vehicle speeds, vehicle age distributions, and vehicle class distributions. These factors are incorporated into a base scenario, which models the current condition on I-85 with HOV lanes, and a future scenario, which models the implementation of HOT lanes on this corridor. The base scenario mainly uses data from a data collection effort by Georgia Tech during the summer of 2007 on the I-85 corridor, while the future scenario makes alterations to these data using information from other cities that have already implemented HOT lanes. The MOBILE-Matrix modeling tool, which was recently developed by Georgia Tech [16], was used to run the emissions analysis using the input factors from these data sources. This tool calculated mass emissions for five pollutants: HC, NOx, CO, PM2.5, and PM10. The results show very small increases in mass emissions for NOx, CO, PM2.5, and PM10, and very small decreases in mass emissions for HC. Therefore, the implementation of HOT lanes on I-85 in Atlanta is unlikely to violate the Transportation Conformity Rule. For NEPA purposes, this analysis could be used to make the case that air quality impacts are not significant, and therefore further detailed analyses are not required.

The aim of this study is to determine whether the introduction of a transport economic regulatory authority would serve as a valid intervention mechanism in the Public-Private Partnership of the transport infrastructure in South Africa. In order to achieve this objective, the study focused on the analysis of the concept of Public-Private Partnership, and how it has unfolded in a number of industrialised countries. Much attention was devoted in examining how the Public-Private Partnership arrangements followed by the studied countries influenced the current transport infrastructure management process in South Africa. To deal with the above, a host of macro-environmental variables were analysed in respect of their potential impact on the South African Department of Transport. The establishment of various agencies by the Department of Transport was seen as a consequence of the influence of the prevailing environmental forces. The outcome of the analysis revealed that a sustainable transport infrastructural development is a product of genuine partnership between the public and private sectors. Competition for the market and the significance of such competition in the transport infrastructure were outlined. The main goal of competition within the context of this study is to diffuse the economic power of the toll road industry and the protection of the individual's fundamental rights. The study also unearthed a need to deepen the talent and skills of both public and private sector officials as this would enable them to protect the citizens' right to make well-considered choices in the toll road industry. The study identified a need to establish a transport economic regulatory authority that would control the market dynamics of power relationships in the transport industry. Such a body should be creative and need to have regulatory oversight over transport infrastructure. / Transport Logistics & Tourism / D. Comm.

This dissertation is concerned with the financing of roads in terms of public finance economic theory. The theory of public goods is applied to the case of roads and it is concluded that roads possess significant elements of privateness and are therefore nonpure public goods. Given that roads are nonpure public goods, and that the market for roads has natural monopoly characteristics, it is proposed that user charges have a role to play in the financing of roads. Road user charging techniques such as licence fees, fuel levies, tolls, area licensing, parking charges and weight-distance charges are evaluated. The advantages of user charging versus tax earmarking and general fund financing are examined. A road financing system for South Africa is proposed, whereby National roads are financed by user charges, and Provincial and Local roads are financed partly by user charges and partly by general taxes. / Economics and Management Sciences / Thesis (M.Com.)--University of South Africa, 1996.

Thesis (MDF)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The purpose of this research was to understand how value for money (‘VfM’), an important decision pillar in public procurement, is applied in South Africa, and compare the VfM regulated framework with other global practices in the United Kingdom, Canada, Australia, Singapore and Hong Kong. VfM is applied when deciding the most appropriate procurement method that utilises public funds in the most cost effective, equitable and transparent manner. Although VfM is vital in the public sector, it is one of the most misunderstood and controversial procurement aspects. The various actors in public procurement processes tend to complicate this key aspect due to their conflicting objectives in relation to a given project. Chief among these are the political influences on the public managers, which tend to manipulate the procurement choice. Consequently over the years, the VfM assessments performed before selecting a procurement method have not been publicly available, thereby increasing concern on whether VfM is achieved, particularly when involving the private sector through public-private partnership (‘PPP’) arrangements. The study explores the various components of VfM, which are the public sector comparator, risk allocation mechanisms, particularly for the road sector projects, discount rates and post project implementation monitoring systems. More importantly, the research analysed how these various aspects were assessed on procuring the N4 toll road. South African National Road Agency SOC Limited (‘SANRAL’), although it did not have the benefit of a PPP guideline as is the case now, it performed extensive feasibility studies and held a transparent procurement process before selecting the private sector party to the PPP. Interestingly, project that was pre-identified as a PPP procurement model and had political support from both the Mozambique and South African governments from inception in order to make it work. The comparative analysis of the South African PPP framework and the selected global PPP markets revealed that the local VfM guidelines were comparable in most aspects such as the PSC construction and risk management methodologies. However, the South African practices could be further improved with increased transparency incorporated in the procurement process such as the publication of the PPP contract once finalised – a practice common in the developed markets analysed. This will go a long way to increasing acceptance of the PPP procurement model in a market that is tainted with mistrust of same. There is need for the civil servants to be trained on the VfM assessment processes so that such analyses are not limited to PPP-type projects, but to conventionally-procured infrastructure projects for increased accountability and effective use of public funds.

This thesis examines the marginal cost of congested travel to a variety of businesses by observing time spent in congestion and estimating excess labor costs based upon the relevant value of time. The fleets in the scoping study represented commercial deliveries of goods and services, government agencies, and transit systems. Observations on limited-access expressways within the 13-county Atlanta metropolitan region were used in the analysis. Vehicles were monitored by using a passive GPS assembly that transmitted speed and location data in real-time to an off-site location. Installation and operation during the observation period required no interaction from the driver. Over 217 hours of good freeway movement during 354 vehicle-days was recorded. Rates of delay, expressed as a unit of lost minutes per mile traveled, were calculated by taking the difference in speeds observed during congestion from an optimal free-flow speed of 45 mph and dividing that by the distance traveled per segment. The difference between the 50th and 95th percentile delay rates was used as the measure for travel unreliability. Daily average values of extra time needed per fleet vehicle to ensure on-time arrivals were derived, and the median buffer across all fleets was 1.65 hours of added time per vehicle. Weekly marginal costs per fleet vehicle were estimated by factoring in the corresponding driver wages or hourly operation costs (for transit fleets). Equivalent toll rates were calculated by multiplying the 95th percentile delay rate by the hourly costs. The equivalent toll per mile traveled was representative of an equal relationship between the marginal costs of congestion experienced and a hypothetical state of free-flow travel (under first-best rules of marginal cost pricing). The median equivalent toll rates across all fleets was $0.43 per mile for weekday mornings, $0.13 per mile for midday weekdays, $0.53 per mile for afternoon weekdays and $0.01 per mile for weekday nights and weekends.

This paper examines the issues of equity, as applicable to the HOV-to-HOT conversion project planned for the I-85 North corridor in the Metropolitan Atlanta Region. A review of literature is undertaken to describe the typology of transportation equity issues within the wider context of environmental justice, and to highlight socio-economic factors and local and national transportation funding factors that influence people's travel choices and their mobility and accessibility options. Demographic data on the I-85 corridor peak period commuters in Metropolitan Atlanta is analyzed, in addition to results of focus groups polling current Metropolitan Atlanta interstate commuters on the topic of managed lanes during 2008. The thesis makes a conclusion that a final decision about the equity impact of the I-85 HOV-to-HOT conversion is likely not possible without undertaking a Metropolitan area-wide analysis. Some of the equity findings that emerge indicate that there are no significant income differences between the the HOV lane users and general purpose lane I-85 commuters; that there are differences between median incomes of block groups represented by current I-85 commuters (both HOV lane users and general purpose lane users) and median incomes of block groups typical for the base geography; and that investing in Xpress bus service improvements would primarily serve those households with more vehicles than drivers, unless improvements to reverse commute options and feeder bus networks are made. The focus group findings suggest that current interstate highway users in Metropolitan Atlanta, originating in the suburbs, are generally accepting of the HOT concept and recognize the value of travel time savings.

The aim of this study is to determine whether the introduction of a transport economic regulatory authority would serve as a valid intervention mechanism in the Public-Private Partnership of the transport infrastructure in South Africa. In order to achieve this objective, the study focused on the analysis of the concept of Public-Private Partnership, and how it has unfolded in a number of industrialised countries. Much attention was devoted in examining how the Public-Private Partnership arrangements followed by the studied countries influenced the current transport infrastructure management process in South Africa. To deal with the above, a host of macro-environmental variables were analysed in respect of their potential impact on the South African Department of Transport. The establishment of various agencies by the Department of Transport was seen as a consequence of the influence of the prevailing environmental forces. The outcome of the analysis revealed that a sustainable transport infrastructural development is a product of genuine partnership between the public and private sectors. Competition for the market and the significance of such competition in the transport infrastructure were outlined. The main goal of competition within the context of this study is to diffuse the economic power of the toll road industry and the protection of the individual's fundamental rights. The study also unearthed a need to deepen the talent and skills of both public and private sector officials as this would enable them to protect the citizens' right to make well-considered choices in the toll road industry. The study identified a need to establish a transport economic regulatory authority that would control the market dynamics of power relationships in the transport industry. Such a body should be creative and need to have regulatory oversight over transport infrastructure. / Transport Logistics and Tourism / D. Comm.