By the time Bulldog Days rolls around next year, prefrosh and their parents may have an easier time finding hotel rooms in New Haven.

Expansion proposals from both the Marriott Courtyard Hotel on Whalley Avenue and the Colony Inn on Chapel Street will come before the City Plan Commission tonight for approval. The Marriott will seek permission to add 47 new rooms to its 160-room hotel, and the Colony will seek a positive referral from the City Plan Commission to the Board of Zoning Appeals for permission to reduce the number of on-site parking spaces from 219 to 101 — clearing the way for a plan to add 40 rooms to the 86-room hotel, City Plan Commission Director Karen Gilvarg said.

The expansion of Elm City hotels comes in the midst of a national slump in the hotel industry and is a positive indicator of the health of New Haven’s economy, Executive Director of the Town Green Special Services District Scott Healy ’97 said.

“The hotel industry … changed after Sept. 11,” Healy said. “People were really traveling much closer to home. Occupancy rates started to decrease. It happened here as well. [The hotel expansion] is actually a signal that New Haven’s hotel industry is holding its own and expanding naturally.”

Michael Morand, Yale’s associate vice president for New Haven and State Affairs, said the expansions should benefit from an ever-growing New Haven hotel market.

“Both expansions and renovations indicate that investors recognize New Haven as a good market,” Morand said. “There is every reason to believe that the market to serve overnight guests will continue to grow in the years ahead. These two projects will provide an incentive to existing properties to maintain high quality and encourage other investors to look at New Haven.”

But Steven Paganelli, president of the Greater New Haven Convention and Visitors Bureau, said occupancy levels in New Haven have restricted hotels from making bolder expansion moves. Since average hotel occupancy levels in New Haven run just below 70 percent — the minimum a hotel needs to stay profitable — hotels are reluctant to sink too much cash into bricks and mortar, Paganelli said.

“Because of where the occupancy level is … you haven’t seen large-scale hotel development,” he said. “You’re seeing these modest expansions of existing properties, which is much more cost-effective for developers.”

New Haven hotels do sell out on occasion, Paganelli said, especially when Yale-related events such as Bulldog Days, Commencement and Parents Weekend swamp the Elm City with visitors. But the customer base Yale provides is too transient to support an increase in large-scale hotel development, he said, and New Haven will need to look to other sources for a consistent stream of hotel clientele.

“One of the critical pieces to make [development viable] is an expansion of the corporate business base here,” he said. “A lot of the hotels do business in corporate transient travel, and that’s the kind of addition that the market would need to justify that kind of project.”

In recent years, hotel development in the New Haven region has been primarily focused on surrounding areas such as Orange, Milford and Branford, Paganelli said.

“Within the city of New Haven there haven’t been real expansions in recent years, so this is kind of new activity,” Paganelli said. “There have been a lot of hotel expansions outside the city … [but] the city itself has had more of a stable hotel industry.”

Two years ago, Mayor John DeStefano Jr. proposed building a luxury hotel and conference center on the site of the soon-to-be demolished New Haven Memorial Coliseum as part of the $230 million Gateway Project, but a feasibility study released in February determined that the location would not be ideal for a full-service luxury hotel.