The high cost of urban transportation has invariably fallen most heavily on the poorest classes, who pay a higher proportion of family income to 【S1】______ transportation, and often cannot find adequate means of reaching employment. In modern industrial centers new jobs tend to locate away from 【S2】______ file congested districts where the poor traditionally live. Normally walking speed for a man has remained at about 3.1 miles per hour at the beginning of recorded history. Horses and horse-drawn omnibuses 【S3】______ raised the speed of travel to approximately 6 miles per hour. Buses and trolleys providing average speeds of 5 to 6 miles per hour in rush-hour traffic 【S4】______ to 12-14 miles per hour on most city streets in other time periods. Speed of up to 50 miles per hour are often reached by buses in outlying streets of large cities, but schedule speeds, which include stopping times, are much higher. 【S5】______ Studies of relative speeds of principle mid 20th-century urban-transit modes showed average automobile speeds of up to 10 miles per hour, compare with 16 miles per hour for suburban rail roads, and substantially less 【S6】______ for other mass transit. When doubtless valid statistically, such studies are 【S7】______ misleading because of the different functions of the different types of transit To gain a real picture of urban transit speeds in a city like Paris or New York would require a rationale that included a number of persons moved per mile, 【S8】______ how near the center of the city the movement took place, and aim station spacing. Broadly speaking, what may be said that while speed of movement, 【S9】______ especially during rush hours, still leaves something to be desired in most cities, it is as critical a problem as that of costs. 【S10】______ 【S1】