Mount a lengthy advertising and information campaign to encourage drivers into travelling more slowly (50mph suggested). As a final resort, this could become legislation. Exempting electric vehicles and coaches would encourage the use of these forms of transport.
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Transport is the largest source of man made CO2 emissions. Involving the public in a move to reduce these by encouraging slower driving and slower drivers could have several effects-
1 Make slower driving the socially acceptable norm.
2 Reduce CO2 emissons by-
a. reducing fuel usage
b. reducing the interest in longer distance travel,
c. encouraging a move to electric vehicles,
d. encouraging coach travel with its lower per capita fuel consumption.