The document discusses using an economic framework to optimize traffic law enforcement and deterrence of traffic offenses. It presents models for determining the optimal level of enforcement that minimizes social costs. Case studies on speed cameras, bus lane enforcement, and congestion charging enforcement show that the optimal level maximizes social benefits but may not maximize financial benefits for enforcement institutions. The analysis concludes that an economic approach can help improve resource allocation for enforcement and identify the true costs of offenses.

1. TRANSPORT LAW ENFORCEMENT: A FRAMEWORK FOR THE OPTIMISATION OF ECONOMIC BENEFITS Dr. MARK BROWN – HALCROW, UK ETC 2006 STRASBOURG

6. THE OPTIMAL LEVEL OF ENFORCEMENT Number of Offences per year Social Cost £m/yr Enforcement Effort High Enforcement Cost High Damage Cost – too many offences Optima The ideal No. offences!

9. ENFORCEMENT AND DETTERENCE MODELS COST OF ENFORCEMENT, PROSECUCTION AND PUNISHMENT COST OF DAMAGE TO SOCIETY GAIN TO OFFENDERS SOCIAL COST + + = NUMBER OF OFFENCES CERTAINTY OF CONVICTION SEVERITY OF PUNISHMENT

14. Deterrence effects – proportion of current offenders who would still offend 85% 84% 80.5% 78% 71.5% 47.5% 21.5% £60 + 3 penalty points 75% 74% 71% 68% 62% 40% 18% £80 + 3 penalty points 95% 94% 90% 88% 81% 55% 25% £40 + 3 penalty points 1 in 20 1 in 16 1 in 10 1 in 8 1 in 5 1 in 2 1 in 1 Fine Number of cameras in operation

15. Reduction in offences and accidents Data for £60 penalty £35 £37 £46 £53 £71 £154 £304 Reduction in accident cost (’000) £1,919 £1,916 £1,907 £1,901 £1,883 £1,800 £1,650 Annual accident cost (’000) 98% 98% 98% 97% 96% 92% 84% % accidents still occur (P  ) 85% 84% 80.5% 78% 70.5% 47.5% 21.5% % still offending (P) 1 in 20 1 in 16 1 in 10 1 in 8 1 in 5 1 in 2 1 in 1 Number of cameras in operation

16. Costs & benefits of speed cameras 90 52 58 77 121 204 240 Net finance+Social benefit -27 -40 -72 -90 -143 -234 -157 N et social benefits £35 £37 £46 £53 £71 £154 £304 Social benefit (accidents) -£78 -£97 -£149 -£180 -£264 -£438 -£397 Minimum offenders impact £17 £21 £31 £37 £50 £50 -£64 Total for enforcement institutions £78 £97 £149 £180 £264 £438 £397 Penalty revenue -£52 -£64 -£98 -£118 -£174 -£288 -£261 Prosecution cost -£10 -£12.5 -£20 -£25 -£40 -£100 -£200 Enforcement cost Recurrent costs and benefits 1 in 20 1 in 16 1 in 10 1 in 8 1 in 5 1 in 2 1 in 1 Change in impact Number of cameras in operation (ie: no. with film)

19. Bus lane camera enforcement -£4,200 -£5,196 -£8,140 -£10,067 -£15,241 -£30,309 -£37,237 Offenders (lower limit) £ 12,000 £ 16,000 £ 24,000 £ 28,000 £ 48,000 £120,000 £200,000 Wider society -£6,800 -£8,496 -£ 13,581 -£ 16,969 -£27,089 -£67,165 -£132,660 Enforcement institutions Summary of impacts by impact group £12,000 £16,000 £24,000 £28,000 £48,000 £120,000 £200,000 Social benefit of less offending -£4,200 -£5,196 -£8,140 -£10,067 -£15,241 -£30,309 -£37,237 Benefits to offenders lower limit) £4,200 £5,196 £8,140 £10,067 £15,241 £30,309 £37,237 Fine Revenue -£4,500 -£5,567 -£8,722 -£10,786 -£16,330 -£32,474 -£39,897 Cost of punishment -£6,500 -£8,125 -£13,000 -£16,250 -£26,000 -£65,000 -£130,000 Cost of enforcement 1 in 20 1 in 16 1 in 10 1 in 8 1 in 5 1 in 2 1 in 1 Proportion of buses with cameras

21. Example 3 - Congestion charging cameras Addition of one more mobile camera site – Increases chances of Detection from 80% to 82.7% 39% 50% 18.75% 80% 16.95% 82.7% 12% 90% Proportion continuing to offend Probability of detection