Two bills were introduced in the D.C. Council yesterday that would strengthen the city's so-called linkage program by forcing developers to help create low- and moderate-income housing in return for obtaining street and alley closings.

Such closings, in which the city gives developers control over city-owned rights of way, are often required for major development projects.

Under the linkage program, the city arranges for a developer to contribute to a needy cause, such as low-cost housing, in exchange for obtaining concessions from the city.

One bill, introduced by Council Chairman David A. Clarke, would give developers a choice of building the housing or contributing the equivalent amount to a housing trust fund to be created by the council.

In addition, the bill would require commercial developers to pay $5 for each extra square foot of building space they are granted beyond the existing zoning. That money would be invested in low- or moderate-income housing.

A bill introduced by council member Betty Ann Kane (D-At Large) would require the council to charge the fair market value for all closed streets and alleys that are owned by the city or the federal government. Under current law, the council may do so, but no such fee has yet been assessed.

Kane said the council last year closed streets and alleys valued at more than $3.7 million. If her bill had been in effect last year, Kane said, the city would have raised $1.7 million.