Operators of the nation's second-biggest taxi fleet are now accelerating toward their long-rumored extinction, edging towards becoming virtual dinosaurs in the era of ride-sharing monsters Uber and Lyft.

Cabbies have long grumbled that the sky is falling as they lose ground to ride-sharing companies. Now, cabbies in Chicago are pointing to new data that suggests the decline could be speeding up.

About 42% of Chicago's taxi fleet was not operating in the month of March, and cabbies have seen their revenue slide for their long-beleaguered industry by nearly 40% over the last three years as riders are increasingly ditching cabs for ride-hailing apps Uber, Lyft and Via, according to a study released Monday by the Chicago cab drivers union.