With the Downtown Library as good as new and the reconstruction of Mitchell Park Library crawling toward the closing chapter after a series of unwelcome plot twists, officials are now preparing for the grand conclusion of the city's library revival -- the renovation and expansion of Main Library.

The Main Library project -- the last component of the $76 million library bond Palo Alto voters passed in 2008 -- will officially launch Tuesday, when the Newell Road branch closes for construction. The city will commemorate the occasion with an "Aloha Closure Party" between 3 and 5 p.m. at the patio of the library, which is located at 1213 Newell Road. But the real celebration will come in about 18 months, when the Main Library and the campus around it re-opens to the public.

For Palo Alto's energetic community of library enthusiasts, the cheering can't come soon enough. After passing the library bond in 2008 and completing the renovation of the small Downtown Library without a hitch, the city has hit a bit of a rut with Mitchell Park, where the construction of a brand-new library and community center has been bogged down in construction errors, unexpected delays and dozens of change orders that have added more than $3 million to the cost. According to a status report issued earlier this month, the Mitchell Park project is now 82 percent complete. Its opening date, initially set for early 2012, has been pushed to the end of this year.

The Main Library renovation is in many ways less dramatic than the Mitchell Park reconstruction. At about half the cost of the Mitchell Park project -- roughly $22 million -- the renovation includes a construction of a new wing with a program room, restrooms and storage spaces on the south side of the branch; a new entrance lobby; four glass-walled study rooms; upgrades to heating, cooling and electrical systems; and a host of landscaping and roadway changes. Even so, it's a big deal and has gotten bigger since the 2008 vote, as the project expanded and the library has fallen into further disrepair.

"This building is older, and it seems to know that the end is near," Library Director Monique le Conge said. "There's a door that just broke that would cost $4,000 to repair and a number of things are failing. I'm glad we're going ahead with the project rather than waiting until Mitchell Park gets done."

Initially envisioned as an $18 million renovation of the 1958 Edward Durell Stone-designed library building, the project now extends well beyond the facility. According to a project description from Group 4 Architects, the city's project consultants, the simultaneous improvements to the adjacent Art Center and to the Main Library "have presented a unique opportunity to unify this large City-owned collection of public cultural facilities." This means a new public plaza near the library and a new driveway connecting the library and the Art Center.

"Together with the Community Gardens, this becomes a great community asset capable of hosting events of a much wider scope than what would be defined by the individual programs of each of these three components."

Last year, the City Council and the Architectural Review Board had both signed off on the two most recent changes to the project a new driveway connecting the library and the Art Center and a new plaza on the campus.

The schedule has also changed, largely because of complications involving the Mitchell Park branch. Initially, the city had hoped to open the new Mitchell Park library before proceeding with Main Library. Now officials plan to work on both branches simultaneously. Once Main Library closes on April 30, most of its contents will be transferred across the campus to the newly renovated Art Center, which will function as a temporary library starting May 3.

Users will notice some differences. The bulk of the Main Library's collection, the largest among the city's five branches, will be put in storage during the construction. The temporary Art Center library, which will bear the address 1315 Newell Road, will offer what le Conge called "express services" during construction. It will include six public-access computers and a total of 20 seats, le Conge said.

"It's really intended to serve as a place where people can just do quick stops -- to pick up holds or look at magazines," le Conge said.

Other branches will also step up to fill the vacuum. The Downtown Library will now be open on Mondays and its hours will be extended from 6 to 8 p.m. Its program room will also now be accommodating fewer programs to give patrons more sitting room. And the temporary Mitchell Park Library (located at Cubberley Community Center, 4000 Middlefield Road) will offer Link+ service, which allows library users to request books from other California library systems in the Link+ network. The service, which the city temporarily suspended, will now be resumed.

Le Conge said the recent problems at Mitchell Park have created some complications for library staff, who will be left with a shortage of space once both libraries are under construction. This means staff will be doing more outreach by hosting programs at schools and community centers, le Conge said. It also means staff will devote more time to the system's "virtual branch."

"We're calling this the 'Summer of love,'" le Conge said. "We'll be sitting very close together."

City officials are also working to make sure that the types of problems that have plagued the Mitchell Park Library would not occur at the Main Library. Assistant Public Works Director Phil Bobel said staff has "exhaustively analyzed" the problems at Mitchell Park and came up with 20 or 30 changes to the way the contract is structured. At the very least, Bobel said, the changes will allow the city to catch any construction problems earlier in the process.

Even with the recent delays and complications, city officials are feeling optimistic. Library use has been rising, le Conge said, and the feedback about the temporary Mitchell Park library has been overwhelmingly positive.

"There's a lot of people who've said to me, 'We're very happy with the temporary Mitchell Park.' I tell them, 'Just wait to see the new one,'" le Conge said.

Read bullet points about what will change with the Main Library's closure.