Conoco Inc. and Flying J Inc., based here, say they will undertake an aggressive plan to develop a national chain of travel plazas and truck stops.

Under the agreement, Conoco will acquire a 50 percent interest in Flying J's 33 existing travel plazas and will help build an indefinite number of additional plazas, said Conoco spokesman Carlton Adams.Neither company would comment specifically on plans for expansion, but development will be aggressive and will occur as the economy allows, said Phillip Adams, executive vice president for Flying J. "We've had a supply relationship with them (Conoco) for some time, and we would like to grow a little more aggressively in that area.

"We're in this for the long term, and our growth rate will reflect the marketing strategies of both companies," Phillip Adams said. "Conoco brings to the partnership not only its well-founded experience in the oil industry but a brand name recognized for quality products."

Conoco General Manager Rick Hamm of the branded and retail marketing operations called the venture "natural" for the company. Flying J's history as a customer and its reputation in the truck-stop industry enhanced the agreement, he said.

Flying J will operate the truck stops. The diesel islands will be branded Flying J, and gasoline will be branded with the Conoco insignia.

Both brand names will be displayed in roadside signs.

Consumers should notice the change sometime in the next three months, Adams said.

Typical travel plazas will consist of gasoline and diesel fueling facilities, a restaurant, a convenience store, showers and phones.