Gov. Martin O’Malley on Monday announced a transportation package of nearly $650 million for Montgomery County.

O’Malley and Lt. Gov. Anthony Brown also said Maryland will pursue the state’s first public-private partnership for transit to build the Purple Line. That’s a 16-mile light rail line with 21 stations between Bethesda and New Carrollton. It’s estimated to cost about $2.15 billion.

O’Malley also announced an added $400 million investment for the Purple Line project, which would be paid for with a combination of federal grants, private investment and state and local contributions.

O’Malley and the General Assembly approved a gas tax increase this year to help pay for the projects.

Projects announced Monday include:

—$125 million to construct a new interchange along I-270 at Watkins Mill Road.

—$25 million to build a relocated Md. 97 around the historic town of Brookeville.

—$280 million to complete right of way acquisition and final design for the Purple Line. When combined with the new $400 million investment for Purple Line construction, a total of $680 million will be invested.

—$100 million to complete right of way acquisition and final design for the Corridor Cities Transitway.

—$7 million in design funds to build two interchanges along U.S. 29, at Musgrove Road and Fairland Road, to replace existing intersections.

—$3 million in design funds to widen Md. 124 from Midcounty Highway to south of Airpark Road.

—$3 million in planning funds for the Md. 28/Md. 198 Corridor Transportation Improvement Study.

—$85 million in operating assistance for the County’s Ride On Bus for fiscal years 2014-19.