New department heads will move into Boston Transportation, Elections, Inspectional Services, and Property Management as part of a leadership shuffle Mayor Martin Walsh announced last Friday.

“I am incredibly proud to welcome these individuals into these important leadership posts,” Walsh said in a statement. “The work of each of these departments is crucial to our overall mission of serving the residents of Boston in the best way we can, and through these new appointments I look forward to our continued work ahead in making progress on our goals.”

William “Buddy” Christopher, the former head of the Inspectional Services Department (ISD), has been tapped to serve as special advisor to the mayor. He will first focus on “managing the services provided to Melnea Cass and Massachusetts Avenue,” according to a release.

Christopher held his ISD commissioner post for five years, enforcing building, housing, health, sanitation, and safety regulations mandated by city and state governments. The city highlights the department’s work in streamlining the permitting process, increasing the capacity at Zoning Board of Appeal hearings, and increasing transparency around permitting.

Replacing Christopher at ISD will be Dion Irish, a 25-year city employee who most recently served as commissioner for the elections department. Irish worked in inspectional services for 17 years before moving to elections, having served as assistant commissioner and director of Housing Inspections.

Eneida Tavares will be interim commissioner for the elections department. She oversaw implementation of new election management software during her three years as a senior data analyst in the elections department, the mayor’s office said. A native of Praia, Cabo Verde, Tavares has been a resident of Boston for the last 30 years and has spent the past 14 years in public service.

A change in the Boston Transportation Department (BTD) will also kick off a leadership swap. Gregory Rooney has been named interim commissioner of the department. After nine years at the BTD, Rooney joined the city’s Property Management Department and became its commissioner, overseeing maintenance, repairs and security for the city’s municipal buildings.

Rooney will be replaced by Indira Alvarez as interim commissioner at Property Management. She formerly served as the chief of staff and the assistant commissioner at ISD. Born and raised in Panama, Alvarez has worked as a public servant for more than 20 years in the areas of social work, community liaison, code enforcement, and policy implementation.