To estimate the cold start increment (CSI) in the form of fuel/exhaust, travel patterns must be known. The number of journeys is of interest for estimation of average total CSI. CSI can be estimated if distribution of journeys in time and space is known. Average journey length is likely to be a function of town size, town district, time of day and time of year. One problem has been comparability of different sources of information. One important source is the travel pattern survey made in 1984/85 which has comprehensive data regarding journeys which start and finish at a base place, including median trip lengths and times. Journeys are reasonably evenly distributed over weekdays, with slight increase on Thursdays and Fridays. Travel pattern over day varies between weekdays and week-ends. On weekdays, peaks are in morning and late afternoon, at week-ends at mid-day. Average length is 13 km. In summer this may be 50% higher.
Abstract