Transportation Secretary Richard Davey, the longest serving of the governor's the four transportation chiefs, plans to resign at the end of October, leaving the administration two months before the end of Gov. Deval Patrick's tenure.

Davey informed the governor of his decision late last month, and plans to depart on Nov. 1, becoming the second Cabinet official to leave the administration since Patrick asked his top lieutenants to commit in early 2013 to another two years to see the administration through to the end.

"It's time," Davey told the News Service. "I'm going to take some time to travel a little bit with my wife and start to think about what's next for my career. But we have a window to travel now, and I know the governor understands."

Patrick and Davey will be together Friday morning in Waltham at Bentley University for an event. Prior to the appearance, Patrick plans to announce that Highway Administrator Frank DePaola will take over the Department of Transportation on an acting basis until the new administration assumes control in January, according to an administration official with knowledge of the situation.

"Rich Davey has been a key member of my team and one of the finest transportation leaders the Commonwealth has ever had. He has been instrumental in our work to provide every region of this state with a safer, more efficient transportation system, a growing economy and a better quality of life. I thank him for his service and wish him every good thing in the future," Patrick said in a statement.

Davey said he and his wife have a two-week vacation planned to Australia in December and may also travel to Europe in November. "The governor gracefully offered to just give me the time, but in this type of job it's just not possible to unplug and that's not how I'm wired," he said.

On the governor's recent trade mission to England, Denmark and France, Rep. William Straus, co-chair of the Legislature's Committee on Transportation, said he texted Davey in the early evening, not expecting to hear back because of the time difference in Europe. Minutes later, Davey responded.

"That's not a secret formula. It's just hard work," said Straus, who offered high praise for Davey as someone who effectively became an "honest advocate" for the governor and his agenda, while maintaining "a lot of credibility with the Legislature" by never letting his advocacy get in the way of presenting accurate information to lawmakers.

Davey, who helped lead the administration's push last year for tax increases to reinvest in transportation, said he considered the progress made on transportation financing and efforts like the "Fast 14" accelerated bridge replacement program to be among his biggest accomplishments.

Davey also oversaw the implementation of controversial fares hikes at the MBTA to close a deficit at the agency before last year's debate on new revenues, pushed the state toward electronic tolling, and worked to further major public transit projects such as South Coast rail, the Green Line extension, and the Allston Turnpike improvement project.

"Broadly, I'd like to think that we renewed the citizens' faith in transportation. Four and half years ago the Big Dig was sort of a swear word and I think now we've moved beyond that," Davey said. He said he hopes the ballot question repealing a law passed last year linking future gas tax increases to inflation will fail so that the next administration can continue making investments in infrastructure.

As for regrets, Davey said, "I wish I didn't propose banning strollers from buses. That had to be the dumbest idea I floated, but that was mine."

Davey said his next career move is "very likely the private sector," but he did not rule out a future run for public office, either in Massachusetts or elsewhere. The Boston resident, who ironically doesn't own a car, said he'll be looking for a position that might allow him to travel more and expand his portfolio beyond transportation.

"I'm ready to try something else than be a transportation executive," he said, citing interest in the technology start-up world.

Davey took over as secretary of transportation in September 2011, making him the longest tenured transportation chief since James Kerasiotes in the mid-1990s. Prior to leading MassDOT, Davey worked as general manager of the MBTA after running the state's commuter rail system as general manager of the Massachusetts Bay Commuter Railroad, which held the contract to operate the state's passenger rail system.

A native of Randolph, he is a graduate of Holy Cross and Gonzaga University Law School.

Despite being a T rider himself with a background in rail, Davey proved particularly effective at dividing his attention among all modes of transportation, Straus said. "Sometimes intentionally, sometimes by effect, (secretaries) can favor one mode more than another. Even though Rich's background was in rail and the T, I found that he was just as effective and passionate when it came to aeronautical and roads and bridges as rail," Straus said.

Massachusetts Port Authority CEO Thomas Glynn credited Davey with helping the agency become more "green," and praised his efforts to propose free inbound service from Logan Airport on the Silver Line and his support for the Rental Car Center which cut down on bus trips.

Straus also credited Davey with completing the work started by his predecessor Jeff Mullan to implement the 2009 transportation reform law that brought Massport and the Turnpike Authority under one umbrella.