Peak-spreading: How much?

The Nationwide Personal Transportation Study (NPTS) data for 1977 and 1983 show very little evidence of peak-travel-period elongation, so that peak spreading is a poor explanation of the absence of worsening congestion. The peak-spreading that occurred was limited to the smaller metropolitan areas, where the scope for locational adjustments by households and firms to relieve congestion was much less than in the larger policentric metropolitan areas. Blue-collar and sales workers had more off-peak commutes than other occupations (e.g., professionals), suggesting that institutionalized (i.e., compulsory) alternative work schedules are more effective than voluntary spontaneous actions. This view is reinforced by confirmation of the well-known household and family restrictions on flexible working hours.