Metro's escalators have been causing problems this month when stopped -- but also when running.

A 4-year-old girl suffered a severe hand injury Thursday after falling on a moving Metro escalator. And last week, stopped escalators caused a near riot at the busy Dupont Circle station when a smoking escalator closed off one station entrance, pushing crowds out the remaining exit past one barricaded escalator.

Metro officials said Thursday they are revamping safety procedures in the wake of the July 12 Dupont incident and have hired an outside consultant to assess escalator repairs. But they also are advising riders to be careful of moving escalators and to steer clear of any closed off ones because they may not be safe.

The system's escalators have been a persistent headache for both Metro and riders. Some of the equipment is as old as Metro, outliving the companies that manufactured it. The moving staircases are often exposed to the elements. They run for hours daily. Then when shut down, they choke access to the rail system.

Metro escalators and elevators »  588 escalators »  443 of them are 25+ years old »  Four of the seven manufacturers out of business Source: Metro

In May, an average of 89.5 percent of escalators worked, leaving about 62 escalators out of service. But Metro aims for no more than 43 escalators to be turned off at any given time.

Some shutdowns are unavoidable, according to Metro. About 3 percent, or 18 escalators, need to be out of service at any given time for routine maintenance. But about 70 percent of stoppages come from unscheduled repairs, much of it for automatic safety shutdowns.

One L'Enfant Plaza escalator was shut down midday Thursday to be inspected, for example, after the girl injured her left hand while leaving the Seventh Street and Maryland Avenue exit with her parents, according to Metro.

Witnesses told authorities that the girl fell and got her hand mangled in the stairs, D.C. Fire and Emergency Medical Services spokesman Pete Piringer said. She was taken to Children's Hospital with what Metro spokeswoman Lisa Farbstein described as "severe hand injuries."

Typically the transit agency reports about 100 injuries on its escalators per year. But the injuries have increased this year, according to Metro figures, with an average of 10.8 per month through May compared with 7.75 injuries per month in 2009 and 10.3 in 2008.