Investment firm Community Development Trust announced Sept. 30 a partnership with the Austin Affordable Housing Corp., a nonprofit subsidiary of the Housing Authority of the City of Austin, to acquire two market-rate properties totaling 642 units: The Bridge at Center Ridge, 701 Center Ridge Drive, and The Bridge at Tech Ridge, 12800 Center Lake Drive. CDT and AAHC will preserve half of the units in each property for households earning less than 80 percent of the area annual median income. Center Ridge: 512- 634-8487. Tech Ridge: 512-634-8468. www.bridgeatcenterridge.com, www.bridgeattechridge.com