Houston highway crews are busy changing speed limit signs this week on two of the city's major freeways. U.S. Highway 59 and State Highway 146 are getting new signs lowering speed limits to 55 mph as part of a plan by the Texas Natural Resource Conservation Commission to bring the Houston area into compliance with federal ozone standards by 2007.

Last week, U.S. Highway 290 and state highways 225, 249 and 288 were posted with the new 55-mph signage. All of the city's freeways are expected to be in compliance by a May 1 deadline.