The American Trucking Associations Inc., a trade association that has been in the same block since 1945, is seeking to expand its facilities at 1616 P St. NW on adjacent land on P, O and 17th streets.

The proposed $8 million planned unit development expansion is scheduled to be considered today at a public hearing by the D.C. Zoning Commission.

ATA, which has occupied its own building at 1616 P since 1960, wants to build a comparably sized, sixstory office to the west on what now is a parking lot. Part of the site is zoned SP for high-rise office, but another part, closer to 17th

Street and the Berkley House apartment on the corner, is zoned R-5-D.

The total ATA expansion also would include a two-story building fronting on both 17th and O streets. Owned by ATA, that part of the property is occupied by three town houses on O Street, a liquor store in an old building at the corner of 17th and O and a garage and gas station on 17th.

The Berkley apartments and three old town houses to the south of it on 17th Street are not part of the ATA holding.

Donald Tender, managing director for finance and administration of ATA, said yesterday that the trade association originally located in the building at 16th and P in 1945 and stayed there until building a new headquarters at 1616 P 19 years ago. ATA recently sold the corner building.

"Our home has been in this block for 33 years," Tender said. "Like other trade associations, we have grown and now have more than 400 employes of ATA and several affiliated organizations.We simply need more office space and also want to have meeting rooms on our site. ATA is not a developer; it simply wants to grow right here in the District."

Tender said site plans developed by the VVKR Partnership of Alexandria now include first-floor commercial space along the 17th Street side of the proposed two-story building to the rear of the present building because of a suggestion made by the former staff of the Municipal Planning Office of the District. He said a bank branch and a drug store were mentioned as tenants to serve the neighborhood.

However, because of the R-5-D zoning for some of the area, there is neighborhood pressure for some residential construction in the new building. "That would involve a change of plans and direction." Tender said, "and delay a start, but we will go along with what is wanted."

According to present plans, all parking would be underground, and part of an existing alley in back of 1616 P would be closed.