Rain-Related Impacts on Selected Transportation Activities and Utility Services in the Chicago Area

Abstract

An intensive meteorological study of summer precipitation in the Chicago area during 1976?78 furnished detailed data needed to perform a study of the impacts of rain on selected transportation-related activities and on certain utility services. Degree of effect on these activities was studied on a rain day versus non-rain day basis and further on a land use basis to help infer changes in impacts due to urban-influenced increases in rain occurrences, rainfall amounts and storm activity. Added rain resulted in over 100% more vehicle accidents, particularly in the urban area, but the accident severity associated with rain was greater in the rural areas. Rainfall decreased ridership of mass transit systems by 3?5% and apparently this was disproportionately due to midday discretionary riders such as shoppers. Little relationship of rain to pleasure boat emergencies was found but more rain decreased usage of pleasure boats. The number of delays in flight departures from O'Hare Airport was highly related to rain, increasing from only 0.3% of all flights delayed on non-rain days to 18.2&percnt delayed on heavy (≥1.3 cm) rain days. The percentage of the total electrical power outage time which was due to storms varied greatly by power district, ranging from 33% to over 80%. In general, downtown Chicago experienced less time without power due to storms, than did suburban areas. Telephone service was unaffected by rain conditions in Chicago but usage was increased. The results of these selected impacts indicate that an urban-related increase in summer rainfall will lead to certain undesirable impacts on those traveling, particularly by auto or air.