Urban Road User Charging Online Knowledge Base
What Are The Implications For Other Themes?
• Objectives: Scheme design should be derived from the overall objectives of the scheme. A scheme design aimed at maximising revenue from a cordon charge would be theoretically very different from one that is aimed at curbing congestion (Sumalee, 2004b). Congestion relief, environmental protection and revenue generation are the three prominent objectives of existing schemes.
• Technology: Different charging regimes require different technologies. For instance DSRC and ANPR technologies are most appropriate for cordon or area based charging, whilst distance based charging would require GNSS technology. Technology has implications for scheme design in terms of the possibility for the tolling authority to fine tune the toll levels.
• Business Systems: One issue not addressed in this chapter is the link between scheme design on the one hand and administration and enforcement on the other. While the evidence on this is limited, some practical advice can be gleaned from existing schemes and is taken up in Chapter 5.
• Prediction: Scheme design will affect travel in a number of ways, and prediction methods need to be able to reflect all of these. It is recognised that some schemes cannot be modelled within some tactical models. It is still relatively difficult, given the state of the art, to model an area licence scheme without the use of tour based representation. More fundamentally, most models are unable to distinguish between those who might be exempt and other users.
• Traffic effects: Scheme design will have an immediate effect on traffic patterns. Those vehicle uses which are charged will be reduced in number. Depending on the design of the scheme, some of these will transfer to other routes or time of day. Some will switch mode or change destination, while some may no longer be made. The net effect of all of these changes will affect traffic flows, speed and congestion levels, as well as public transport loadings and waiting times.
• Environment: Scheme design will directly affect the environment through the reduction and relocation of traffic. In this way, scheme design can be used to focus on relief of environmentally sensitive areas. It is also possible to intensify these effects, as discussed in Chapter 8 by reducing road space.
• Economy: More research is needed to understand the nature of land use and the wider economic implications of various scheme design options. For example, the exact location of tolling points on the network might affect businesses since some businesses located inside the cordon might lose out due to reduction in shopping traffic.
• Equity: This bears a close relationship to accessibility. Accessibility to jobs and opportunities might be increased for disadvantaged groups travelling by public transport since they benefit from reduced congestion; on the other hand, disadvantaged groups that are captive to the car may be made worse off.
• Appraisal: The appraisal process focuses on assessing a proposed scheme to consider how well it might fulfil the objectives. Information obtained through this process can be used to iteratively refine scheme design elements such as charge levels, location of cordons and mitigation measures to counter negative impacts
• Acceptability: Decision makers focus on the simplest designs, and may be overlooking designs which achieve greater economic benefit. On the other hand, acceptability of the scheme may dictate a simpler design. Hence cities might approach the scheme design process with “one hand tied behind their backs” and scheme design is subject to practical acceptability constraints. On the other hand, extensive exemptions, to cater to acceptability and for political expedience, might reduce the effectiveness of the scheme in meeting other objectives. As a generality, the scheme design is likely to be more acceptable if it is developed in discussion with stakeholders.
• Transferability: Scheme designs that are considered optimal will vary from region to region. This is due to factors such as network topology, local geography etc. However, the process of generating insights from various prediction/appraisal tasks will be similar and the ensuing iterative scheme design refinement can be applied.
• Implementation: Scheme design is a lengthy process, and it needs to be iterative and flexible and closely linked to the political decision making process, for implementation to happen.
• Evaluation: Evaluation and monitoring will give important feedback on how well objectives have been met by the scheme design. Scheme design elements can be further developed and fine-tuned already 1-2 years after implementation, as a result of the evaluation exercises.