CAMDEN, Maine — There is a simple truth that Maine small towns would do well to learn and embrace, Dan Burden says. The lower the speed of vehicles passing through, the higher the retail sales at downtown shops and restaurants.

Burden, a national expert in making downtowns pedestrian-friendly, was the guest speaker at workshops hosted by The Friends of Midcoast Maine in Thomaston on Monday and in Camden on Tuesday.

Slowing down traffic is much more complicated than posting lower speed limits, though, as workshop participants learned.

A group of 30 participants ventured out of the town office building Tuesday morning onto Washington Street to see downtown Camden through Burden’s eyes. The tour had barely begun when Burden stopped everyone. Out came a carpenter’s tape measure and Burden noted the width of the travel lane of the one-way side street was 10 feet.

Most travel lanes should be 10 feet wide in downtowns, he said, though transportation planners typically have built them at 13 feet. Burden measured the parking spaces on the street at 8 feet; too wide, he said.

“We still have that duty to move traffic,” he said. “But the first rule is for the traffic to obey the rules of the community.”

When some participants suggested that Maine’s Department of Transportation might not agree, Burden assured them they’d “be surprised how much change you’re in charge of.”

Narrowing street width is just one way to get drivers to slow down. Psychological “traffic-calming” cues such as adding street plantings, different colored paving and edging and islands have come into common use in many parts of Maine. But in the walking tour, Burden revealed finer points of boosting downtown economic and cultural viability.

While working for Florida’s state transportation department, he observed that traffic engineers drove through the intersections they planned to modify. After insisting they walk through and around intersections, the designs got better, he said.

“You’re going to be the pioneers,” he said, not the DOT.

Downtown Camden scored many points with Burden, but rather than praise town leaders, he noted where improvements could be made. Stopping on Elm Street in front of the Rite Aid, which the town planning board mandated have a pitched roof with dormer windows, he doled out praise.

“This is one of the better Rite Aids I’ve seen in America,” Burden said. Then he quizzed participants: “What’s the ugliest thing on this street?” After a moment with no responses, he pointed to the trash receptacles. Residents defended them, noting that the flower boxes that sit atop them have not yet been filled.

Later, in a slideshow, Burden showed trash receptacles from other towns, including some topped with copper and decorated with thought-inspiring quotes.

One phrase participants heard over and over during Burden’s presentation was back-in, diagonal parking. Most Maine downtowns have a mix of parallel and diagonal parking spots but few if any have parking that requires drivers to back in diagonally.

Such parking schemes create more spaces, and, according to Burden, are the easiest and safest for drivers to use.

“Every off-street parking space created takes three times as much space as on-street parking,” he said.

Roundabouts, also known as rotaries, also were a theme Burden touched on repeatedly.

He recommended Camden consider creating a small roundabout at the Union Street/U.S. Route 1 intersection at the southern gateway to the town and a very small, perhaps elliptical roundabout where Route 1 intersects with Route 52 and Main Street at the northern gateway. Both could have centers with pavers that are raised a few inches, thereby allowing big trucks to roll over them as needed.

Roundabouts move 30 percent more traffic in a given time than intersections with stop lights and stop signs, he said, and cut personal injury crashes by 90 percent.

“Gateways should draw people out of their cars from that point on,” he said, with plantings, information kiosks and banners, all tools to signal the entrance to a walkable, interesting downtown.

Burden also described how sidewalks with the right “furniture,” such as benches, and tree canopies of the right height can draw travelers out of their cars. He recounted how a pretty fountain once led to him look for half an hour for a parking spot in a downtown, which led to him shopping there and buying a $1,000 camera lens.

“Now, I needed a new lens, but I didn’t need to buy it there,” he said.

Though Burden conceded that some of his recommendations required significant investment, he said that businesses reap far greater profits when the downtowns that host them are vibrant and and pedestrian-friendly.

The workshops also were hosted by the Penobscot Bay Chamber of Commerce and the towns of Camden and Thomaston.