Section 51.213 - Transportation control measures(a) The plan must contain procedures for obtaining and maintaining data on actual emissions reductions achieved as a result of implementing transportation control measures.(b) In the case of measures based on traffic flow changes or reductions in vehicle use, the data must include observed changes in vehicle miles traveled and average speeds.(c) The data must be maintained in such a way as to facilitate comparison of the planned and actual efficacy of the transportation control measures.61 FR 30163, June 14, 1996