Trip Characteristics and Travel Patterns of Suburban Residents

Increasing traffic congestion in U.S. suburbs can be explained to a large degree by their rapid growth. Much is still to be learned, however, about the causes of and variations in traffic congestion. The results of investigations of variations in travel behavior across social groups and between locations are presented. The investigations were based on a mid-1989 mail-back survey of individuals residing in selected Chicago suburbs. Four prominent factors associated with traffic congestion are residence location, population aging, working women, and fixed work hours. Residence location in outer-ring, low-density, growing suburbs implies longer trips and more local trips because of low density and more employment opportunities, respectively. The average travel speed by automobile is higher for residents of growing suburbs, but because of longer commutes they still stay in traffic 25 percent longer than residents of stable suburbs. Population aging may offer some relief to suburban traffic congestion, not because older people travel less, but because they make better use of off-peak periods and shorter trips. Hence, their travel behavior may equalize use of the roadway infrastructure over the day. The increasing number of working women and mothers further contributes to congestion because Jong work trips are added to the large number of household maintenance trips made by women. The morning and evening peak periods remain short in duration. It would make a tremendous difference in peak loads and network performance if the observed lY2-hr peak were spread over 2Y2 to 3 hr.