(Source: Bloomberg)

Tim O’Toole, who ran the London Underground for six years and oversaw the railway’s multibillion- pound upgrade, plans to step down.

O’Toole, 54, a lawyer from Pittsburgh and former chief executive ofConsolidated Rail Corp., will leave Transport for London in April and return to the U.S., the agency said in an e- mailed statement today. A successor hasn’t been picked.

O’Toole supervised the largest investment since World War II in the 146-year-old railway, the aftermath of terrorist attacks on city trains in 2005 and the collapse of the railway’s biggest contractor, Metronet. The railway, which struggled to keep pace with increasing demand, has improved performance since 2005.

“After six years in London it is time to go home,” O’Toole said in the statement. “I am particularly proud that London Underground employees have achieved record operating results and all-time high levels of customer satisfaction in this past year.”