As a mass communications major at Southern Adventist University, Donnie Keele studied ways to send messages out to large groups of people.

On Tuesday, he put his training into practice, sending out a very special message to everyone passing between Bonny Oaks and Ooltewah on Interstate 75, including one very surprised bride-to-be.

“I thought I’d just do something that would have a good story to tell at the end,” he said.

With the help of about 25 friends and family members, Mr. Keele proposed to Rachel Hopkins, his girlfriend of two years, by pretending his car broke down, convincing her to come pick him up and, from a newly constructed overpass, unfurling a banner asking her to marry him.

“She said yes — fantastically enough,” he said.

Mr. Keele, a graduate who works as the university’s assistant chaplain, knew it would take a grand effort to surprise his future wife.

“I think, for the most part, not a lot of people knew because I find things out,” said Ms. Hopkins, a senior at Southern Adventist.

Several times over the last two weeks, Mr. Keele told Ms. Hopkins his Ford Contour was showing minor problems. The car ran fine, but friends excused the untruths.

“It was trickery, but it was his only hope for any kind of surprise for Rachel,” said Ben Stitzer, a senior classmate of Ms. Hopkins who was in on the scheme.

Ms. Hopkins, who was on the Southern Adventist campus when she got the call, initially tried to find someone else to go help her husband-to-be after his breakdown. But Mr. Keele insisted she had to come.

“He was kind of being a jerk on the phone,” she said, explaining that all was forgiven once the 25-foot sign was unrolled.

While she was driving to see Mr. Keele, a TDOT employee paid him a visit.

“I told him what I was doing and he was like, ‘Oh, cool’ and then rolled on,” Mr. Keele said.

Mr. Keele said the couple agreed they wanted a fun story to tell about their engagement, and the story already is being retold.

“I’ll probably tell it another 20 times before the day is over,” Ms. Hopkins said Tuesday.

She said she was looking at dates in May for the couple’s wedding.

As for the wedding planning, Mr. Keele said the hardest part for him is done.

“She’s working on that,” he said.