Table 1

Modelled average traffic contribution along HTRs (>10 000 vehicles circulating per day) to the annual average of NO2 and PM10 concentrations (in micrograms per cubic metre) by circular zone in Rome

Circular zoneNumber of segments with traffic dataLength of segments (m)Number of HTR segmentsLength of HTR segments (m)20012005 without policy scenario2005 with optimistic policy scenario2005 with pessimistic policy scenario
Outside main ring20041 323 052543463 19221.36.816.25.516.25.516.25.5
Main ring1147541 428459214 04622.97.617.
Green strip1584472 273710202 36026.39.720.27.620.27.620.27.6
Railway ring1653292 50250196 91323.39.317.
Limited traffic zone20135 77115293619.76.514.
Total65892 665 0262228979 44722.97.817.
  • We assumed that traffic composition only changed in the Railway ring and in the limited traffic zone.

  • HTR, high-traffic roads.