Harkness Tower may be getting some competition — though not for several years.

According to the University’s latest plans for the two new residential colleges, targeted to be open by fall 2015, one of the towers in the northern college may rival Harkness not only in size, but in sound: At 190 feet, the tower on the west side of the college will now stand 26 feet shorter than Harkness, University Planner Laura Cruickshank said, but like Branford College’s belltower, the new tower, too, could one day house bells.

Although Yale does not yet have the money to start construction on the colleges, it does have enough in donations to pay for continued design work by architects from School of Architecture Dean Robert A.M. Stern’s ARC ’65 firm and University planners. The Office of Development secured enough gifts over the summer to see the design process through to completion, allowing Stern to spend the next year and a half refining and updating his original plans with details as small as the woodwork in individual suites, administrators said.

“We’re moving forward to a more detailed stage,” University President Richard Levin said, “a stage when we’re starting to look very specifically at how each floor is arrayed, all the suites, common rooms, detailing, woodwork, trim.”

The architects and planners have been meeting regularly to push the proposed designs from the conceptual phase to a more concrete stage, Stern said. New renderings released two weeks ago show a few subtle changes from the illustrations Yale released in May 2009, but among the most visible are the colleges’ three towers, one in the south college and two in the north college, which are now considerably taller.

The towers have been made taller so they will be more visible from central campus, as well as to better fit the scale of the surrounding buildings and the proportions of the colleges themselves, Yale major projects planner Alice Raucher said.

“The towers were placed strategically to make visual connections from the colleges to central campus,” Raucher said.

As for turning the northwest tower into a belltower, Cruickshank said her staff is currently studying the possibility.

A group of students and alumni have expressed interest in installing bells, Levin said, adding that the tower would house ringing bells instead of the carillon that sits inside Harkness.

“I think if you’re going to have modern medieval towers, you want to have music emanating from them,” Levin said. “I don’t think the logic was any deeper than that.”

But most things remain the same as when Stern first unveiled his vision for residential colleges 13 and 14: Both colleges, which will house 425 beds each, will be built of brick with stone embellishments, and both will have one main courtyard and a few smaller courtyards. All student bedrooms will be singles, Levin said, and most suites will be quads or sextets, some in the towers themselves. (Elevators in both colleges will make all student suites fully accessible, Raucher added.)

Stern will present the nearly finalized renderings to the Yale Corporation at its annual April meeting, Raucher said. If the Corporation approves the plans, the architects and planners will move into the construction documents phase, developing the designs to the point where they can serve as blueprints for construction, she added.

Before even entering the construction documents phase, the architects are consulting with engineers, landscape architects and electricians, all with an eye to making sure the buildings can be built efficiently, Stern said.

“We’re not just going in with a blind eye,” he said.

In the meantime, the University must also continue to win support from the city for the projects. Yale plans to formally file plans with the city this fall to obtain zoning approval, Associate Vice President for New Haven and State Affairs Michael Morand ’87 DIV ’93 said.

And, of course, Yale still has the monumental task of raising enough funds — about $500 million — to pay for both colleges.

A few major donors provided the funds for ongoing design work over the summer, but no major gifts for the colleges’ construction came in, Vice President for Development Inge Reichenbach said, adding that the summer is normally a slow time for soliciting gifts from donors, many of whom go on vacation in July and August. By the time design work is finished in spring 2012, Levin said, administrators hope to have raised enough to break ground.

The colleges will take 30 months to build, Cruickshank said. That timeline means workers will have to start construction by March 2013 if the colleges are to be ready for incoming freshmen in fall 2015.

But Levin said Yale officials are wary of breaking ground before they have the money to fund the projects. So, he cautioned, that timeline is still shifting. And unlike the School of Management, which may sell bonds to raise money to speed construction of its new campus, the University will not take on more debt to make sure the colleges are built quickly, he said.

Yale has already taken on about $1 billion in debt in the past year and a half. To sell even more bonds might jeopardize its triple-A credit rating, the highest designation possible, credit analysts have said.

“We don’t have room in our budget to carry the debt,” Levin said.

Before the endowment’s 24.6 percent tumble in 2009, officials had planned to raise money to cover half the colleges’ cost and borrow the rest. The colleges were originally slated to open in 2013.