WATERVILLE — Despite earlier police warnings not to block traffic, a line of cars waited on Kennedy Memorial Drive on Wednesday to turn into the J&S Oil car wash, and another, smaller line had formed in the median coming the opposite way.

The car wash at J&S Oil is the only in-bay automatic car wash in this service-center city that has a population of about 16,000. The next closest automatic car wash is about 6 miles away in the neighboring town of Fairfield next to the Purple Cow House of Pancakes off Route 201.

Frustration over backups and long waits at the city’s only automatic car wash has highlighted a simmering problem that involves city planning, economic development and police enforcement along one of the main traffic arteries in Waterville.

Waterville Police have long been receiving complaints about the traffic issue, according to Chief Joseph Massey, who asked residents to stay out of the way of traffic and wait in the parking lot instead. Police are going to start patrolling the area and warning people to move their cars if they’re idling in line on Kennedy Memorial Drive, which is also Route 137. The next step will be issuing tickets for obstructing a public way, Massey said.

Karen Snyder of Waterville said she was waiting 10 minutes and watched more than 10 cars turn from the line waiting in the road into the business before her, while she waited in the median on Wednesday. People were cutting her off and she was fed up.

“It stinks,” she said. “They need to open another one. … I hope they do something.”

Snyder normally wouldn’t wait in the line, but she had a friend in the car with her and she had a coupon for a free wash, she said. She prefers the automatic wash to self-serve, where she said she feels like she has to race the clock. She ends up spending more money using the self-serve car wash just to get enough time to do it right, she said.

In 2015, Jerald Hurdle had proposed to build an automatic, 24-hour car wash on Kennedy Memorial Drive, but the proposal failed because the property was not in an allowable zone and residents who closely abutted the property worried about the disturbance it would create.

City Planner Ann Beverage said the trick would be to find a lot that is large enough and in a commercial B, C or D zone, though the city is flexible with rezoning, she said, as long as it is appropriate.

Despite the attempt to add a second automatic car wash in the city and the long line pouring out onto the road, the company that owns J&S Oil and its car wash says Waterville isn’t big enough to sustain two such businesses.

“We don’t do enough business,” said Richard Smith, vice president of Nouria Energy, a Massachusetts-based company that owns multiple convenience stores, car washes and pet washes across New England, including the J&S Oil and Xpress Stop in Waterville. “I wish we had lines like that all the time, but we don’t.”

According to Smith, the reason for the backups is simple. The car wash was recently bought and changed to a Golden Nozzle Car Wash, a company that owns a chain of 29 car washes spread throughout New England. To celebrate that, the company sent out about 75,000 coupons for free car washes to surrounding businesses within 6 miles last week.

Because of the bad weather, people now have limited time to use their coupons, he said, which expire Tuesday.

“You won’t see that much more moving forward,” Smith said.

While he acknowledged that lines do form a couple of times in the winter because of bouts of bad weather, he said it’s been a whole week of lines because of the coupon.

Asked whether the monthly special, which gives customers unlimited car washes for $19.99, was also adding to the volume, he said the program actually helped make the process more efficient, because there’s no need to run credit cards, and the cars can just go right through.

“We have had long lines of traffic backing up as far back as last year,” Massey said. “It’s a great car wash. Everyone likes it. This didn’t just come about because of those coupons and a free car wash, but it certainly exasperated it.”

Massey thinks the problem worsened after recent heavy snow in the region, which lured drivers to the car wash, coupled with the $19.99 monthly promotion.

The only other car wash in Waterville is at Kennebec Express Lube, but it’s temporarily closed for renovations.

Chet Ficker, the owner since 2012, said they’re rebuilding the floors of the four self-serve car wash bays after the heating failed over a year ago. They plan to reopen the car wash in mid-March and hope the extra bays will help relieve the demand.

People seem to prefer automatic car washes to self-serve ones. Nouria Energy’s Smith said they get more customers through their automatic car wash versus their self-serve washes. Ficker said he probably gets about half the cars an automatic wash does.

“I think the trend for people right now is they like the automatic, they like the simplicity,” Ficker said. “But it costs the user twice as much.”

Ficker’s car wash cost $3 for more than four minutes, and it will probably be similar with the new system, he said. Still, Ficker said he’d love to put an in-bay automatic in his business — but the starting cost would be $250,000.Twitter: madelinestamour