Harvard today released a report that sketches key housing, transportation, and landscaping proposals for the University’s long-term expansion into Allston.

The report shows, with graphics for the first time, several of the possibilities for development across the Charles River in Allston that University planners have been discussing publicly for more than a year.

Executives at Cooper, Robertson & Partners, the planning firm that prepared the report, were quick to emphasize that the proposals remained at a conceptual level and that individual buildings had not been designed.

“There’s a series of issues that are academic and not for us to judge upon,” said David McGregor, the firm’s managing director, referring to ongoing dialogue within the University over what schools and departments will move across the river.

Over the summer and fall, Harvard officials will shop the report around to professors, students, and Allston residents for comment. Later, the University must work with the Boston Redevelopment Authority to update its master plan for Allston.

Harvard last changed that plan in 1998, a year after announcing that the school had secretly purchased 52 acres of Allston land through a front company.

Today’s report does not include a timetable for planning or construction. But it does divide Harvard’s Allston holdings into two zones, one available for building by 2010, and another­—which is currently composed mainly of rail yards—that will be constrained for more than five years.

Kathy Spiegelman, Harvard’s top Allston planner, said that the land available in five years includes some tenants whose leases will expire before 2010.

“By no means is this the project of a single decade, or, I suspect, a single generation,” said University President Lawrence H. Summers, speaking in a conference call with reporters today.

But the preliminary designs reinforce several widely-circulated proposals for the development of Allston. Undergraduate Houses, graduate schools and housing, laboratories, and an enhanced Charles River crossing are all components of the report.

A SPACE FOR SCIENCE

One of the administration’s top priorities appears to be the construction of laboratory space to house cutting-edge initiatives like the Harvard Stem Cell Institute.

In April, the Allston Science and Technology Task Force recommended that Harvard build two 500,000-square-foot science facilities.

“The University’s goal is to move forward expeditiously with plans for [the] first building,” today’s report reads. And Summers said he “would not be surprised” to see laboratory construction towards the beginning of Allston development.

The report plots three potential sites for science facilities: one opposite Western Avenue from the 213-unit Charlesview apartment complex; a second between Charlesview and Harvard Business School (HBS) centered on Ohiri Field, and a third using parts of both sites.

THE NEW RIVER HOUSES

The report also details the potential sites for four undergraduate Houses­­—to hold a total of 1,500 students—on the south shore of the Charles River.

Among the proposals, first reported by The Crimson last week, is one that places Houses between Harvard Stadium and the river, a spot currently occupied by College athletic facilities.

Another plan appears to appropriate existing HBS dormitories next to Soldiers Field Road for Houses. Still another would build new Houses on empty land between HBS buildings near the Weeks Footbridge.

Summers said, however, that expanded undergraduate housing in Allston did not mean the College was trying to swell its student ranks.

“The priority for Harvard College now has to be increasing the faculty-student ratio...we’ve never contemplated the possibility of growing the College over the horizon of the next decade,” Summers said.

THE NEXT CONNECTION

Whatever components of the University eventually relocate to Allston, planners say that a reliable link between the two campuses will be essential.

Currently, cars and pedestrians cross the busy Larz Anderson bridge connecting John F. Kennedy and North Harvard Streets. Pedestrians can also use the Weeks Footbridge to the east. But that bridge, built in 1924, fails to comply with the Americans with Disabilities Act, according to McGregor, Cooper, Robertson’s managing partner.

The report sketches possible improvements to both bridges, including aligning the Weeks Footbridge with DeWolfe Street and adding a lane for transit.

But two other proposals suggest constructing a new crossing entirely. One plan would extend the existing MBTA bus tunnel in Harvard and Brattle Squares underneath the Charles to emerge near Harvard Stadium.

And another plan would erect a bridge on Harvard property between the two existing bridges. It would permit cars to drive from Mill Street, between Gore and Standish Halls of Winthrop House, to East Drive on the current HBS campus.

Spiegelman said that whatever the crossing, Harvard’s mode of transit for crossing the river—buses or light rail have both been discussed—has not been decided.

A NEW LANDSCAPE

Another improvement that the report suggests will be likely in any case is a revamping of Allston’s landscape.

“Allston needs more and improved green spaces, and better access to them,” the report reads.

“Part of the issue is to make the connectivity quicker. [Another part] is to make it a much more enjoyable experience,” said Alan Altshuler, the dean of the Graduate School of Design and a member of Harvard’s Master Planning Advisory Committee.

Accordingly, the report outlines several measures to free up green space and provide a more pleasant trip for travelers from Barry’s Corner (the intersection of North Harvard Street and Western Avenue) past the Larz Anderson Bridge.

A canal dug through the current athletic fields northwest of Harvard Stadium could manage surface water and provide a place for skating and hockey in winter, according the report. And if Houses are built near the athletic facilities or HBS, the report suggests that Soldiers Field Road could be rerouted underground to allow pedestrians direct access to the river.

CAMPUS AND COMMUNITY

Harvard’s provisional report is more narrowly focused than the North Allston Strategic Framework for Planning, which the city of Boston released last October.

That report called for a tight integration of Harvard’s Allston campus and existing North Allston communities.

While today’s Harvard report mostly focuses on its own campus, some sketches show graduate schools or cultural centers replacing the Charlesview apartments northeast of Barry’s Corner.

Harvard is currently negotiating with Charlesview to relocate the complex to another area in Allston or Brighton, but some Charlesview residents have expressed dissatisfaction at Harvard’s dealings.

Ray Mellone, the chair of the Harvard Allston Task Force and an Allston resident, said that he had the report but had not read it yet.

—Staff writer Brendan R. Linn can be reached at blinn@fas.harvard.edu.