What do we mean by packaging?
Most SUMP strategies are developed either in pursuit of synergy, or as a means of overcoming barriers, or both.
Synergy occurs when the simultaneous use of two or more instruments gives a greater benefit than the sum of the benefits of using either one of them alone:
Welfare gain (A+B) > Welfare gain A + Welfare gain B.
Synergy as defined is a special case of complementarity, which exists when the use of two instruments gives greater total benefits than the use of either alone:
Welfare gain (A+B) > Welfare gain A, and
Welfare gain (A+B) > Welfare gain B.
Most analysis of contributions to synergy comes from predictive models indicating what might happen if two or more measures are used together. These studies show little evidence of true synergy in performance against objectives, though there is some evidence of synergy in responses within the transport system, such as changes in modal share. This is not surprising; two individual measures in a strategy designed to reduce, say, the adverse impacts of car use, will both impact in part on the same group of users. Their combined impact on car use will thus be less than the sum of their impacts taken individually. However, complementarity is very likely to occur, implying that the two measures will be more effective than either on its own. As described more fully in Complementary Measures Option Generator: scoring, the synergy scores used in KonSULT have been developed in a detailed model-based analysis of a range of typical pairs of measures.
The principal barriers to be overcome in strategy development have been identified in KonSULT as legal and regulatory; financial; governance and institutional; political acceptability; public acceptability; and technical. Financial and acceptability barriers, in particular, can be overcome by careful integration of different policy measures, thus increasing the chance of the strategy being implemented. However, the overall benefit is likely to be less; thus a strategy focused on overcoming barriers is likely to be less effective in meeting the objectives than one designed in pursuit of complementarity. Conversely, it may be more easily implemented. As described more fully in Complementary Measures Option Generator: scoring, the barriers scores used in KonSULT are those specified in the Policy Guidebook description of each measure.
London offers a good example of both principles of packaging. Congestion charging was unpopular, and was expected to affect lower income car users. However, its revenue was used to finance an increase in bus services in inner London. These bus services helped overcome the acceptability barrier to congestion charging, while congestion charging overcame the financial barrier to increasing bus services. Moreover, the two together achieved a greater switch away from car use than either would have done on its own, thus achieving complementarity, if not full synergy.