The wait’s going to be a bit longer for Sound Transit’s choice on a preferred light rail route and station locations along its SeaTac to Kent and Federal Way extension.

The Sound Transit Board, which will pick a preferred route for the more than $1 billion project, decided to postpone a decision to July 23 from June 25 to give it more time to study and hear about the options.

The Capital Committee of the Sound Transit Board voted unanimously on June 11 to move the issue on to the full board without a recommendation about whether to build the 7.6-mile light rail route along Interstate 5 or Highway 99 and which of nine potential locations for a station in Kent/Des Moines near Highline College.

Fred Butler, chairman of the Capital Committee and mayor of Issaquah, said the extra month will give time for more comment from the public as well as the cities impacted by the decision.

“I do like that the four cities reached a consensus on a preferred alternative,” Butler said at the meeting.

Kent, Des Moines, SeaTac and Federal Way city officials each favor an I-5 alignment to lessen the impact of businesses along Highway 99, said Cathal Ridge, light rail development manager, during a report to the committee.

“I-5 is less costly, has less commercial impact and less noise and visual impact,” Ridge said.

Kent and Des Moines officials each prefer a light rail station on the east side of Pacific Highway South near Highline College, where officials and students prefer a station on the west side closer to campus. All favor a pedestrian overpass over the highway if a station is built on the east side near 30th Avenue South.

Other people during public comment sessions told Sound Transit they prefer the Highway 99 alternative because the route would provide better access to activity centers and have less residential impact. About 285 residential units would need to be removed in the Kent-Des Moines area for the I-5 route.

Ridge said the estimated costs are higher for the Highway 99 route because the tracks would need to be elevated, utility relocation costs are more and  additional properties would need to be purchased.

Sound Transit plans to expand light rail from the Angle Lake Station at South 200th in SeaTac, which opens in 2016, to Kent/Des Moines at South 240th Street by 2023 and then the full 7.6 miles to Federal Way near South 320th Street when more funding is secured.

King County Councilman Dave Upthegrove, who represents the Kent-Des Moines area and serves on the Sound Transit board, agreed to delay the decision.

“To give the board time to July to process is a good idea,” said Upthegrove, whose Des Moines home sits about one quarter of a mile from the proposed route. “This encourages the board to dig into the details.”

Seattle City Councilman Mike O’Brien, also a Sound Transit board member, said the extra month will give more time to work out a few of the differences in opinion about a preferred route for the tracks and station locations.

Once the board picks a preferred route for the Kent/Federal Way extension, staff will prepare a final environmental impact statement (EIS) for the preferred route with a final board decision to be made next year.