http://www.chicago-l...s/blizzard79.html
According to the U.S. Department of Commerce Weather Bureau, Chicago's average annual snowfall is 33" and rarely exceeds 40". Since records began to be kept in 1899, there have only been four winters in which total snowfall exceeded 60". But during the winter of 1978-79, the total was a staggering 88.4"! And by the end of January, there was an accumulation of more than 47" on the ground, most of which was compacted ice!
The Blizzard of 1979 started on Friday night January 12 and lasted until 2 a.m. Sunday January 14. On top of 7-10 inches left over from a New Year's Eve storm, 20.3 inches of new snow fell--setting a record for total snow on the ground.
Transportation came to a standstill for several days. The CTA had snowfighting equipment, mostly cars fitted with small snowplows suitable for the 8"-12" of snow that usually falls at any one time. But it soon became apparent that these were inadequate against the 27" of snow on the ground and so the shops manufactured makeshift plows of heavy plywood laid in cross-grained layers of up to 6". The use of wood instead of steel kept the plows insulated against the 600 volt DC third rail. The plows were attached to the front of married-pair units, using both designated work cars and revenue units from the passenger fleet.
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Any city will have trouble with a major storm that happens every 15-30 years or so. E.g. http://en.wikipedia....rm_of_the_Century
Cheers,
Scott.