Traffic lights are to be installed beside the scenic Clachan Bridge on Scotland’s wild Argyll coast despite fears it will be a “desecration” of a nationally-significant heritage site.

Known since the early 19th century as the “Bridge over the Atlantic” the 233-year-old crossing from the mainland to the Isle of Seil attracts visitors eager to boast of their trans-oceanic journey, but there are concerns motorists on green will soon act aggressively towards pedestrians on what is a much-photographed landmark.

“There was no contact from the council,” fourth-generation islander Sarah Nicholson said. “We only found out about the plan when workmen started digging up the road.”

The next traffic lights south will be 35 miles away in Lochgilphead, the base for Agyll and Bute council, which is spending at least £35,000 on the installation.

Located 13 miles south-west of Oban and built in 1792, Clachan Bridge is a signposted tourist attraction, with visitors often getting out of cars and buses to walk over the narrow tidal channel that opens out into the north Atlantic. The footway on the humpback bridge fades to almost nothing, leaving pedestrians to share the narrow road with motorists who currently negotiate the crossing carefully.

With a width barely able to cope with today’s SUVs, the council says it has to install traffic lights on the bridge for “road safety”. However, the Guardian has found reports of just three collisions at the bridge in the 25 years between 1999 and 2024, each described as only “slight” in severity.

Police Scotland “supports the initiative to reduce the risk of road traffic collisions at this location” but admits it “has not provided any advice regarding cyclists or horses, pedestrians, tourists using the bridge”.

Residents and a local councillor say the scheme has been implemented without consultation, without evidence, and without input from heritage bodies. The bridge is part of a historic landscape, they say, and argue that the intervention risks damaging the bridge’s bucolic setting and the visitor experience.

Local councillor and seventh-generation islander Julie McKenzie organised a petition against the traffic scheme, which swiftly gathered 1,500 signatures, three times more than the area’s population.

“If Clachan Bridge was a crash hotspot, there’s nobody in this community who would be against a traffic calming measure,” she said. She also has heritage objections. From the inn opposite the bridge, McKenzie said the council did not consult Historic Environment Scotland (HES) before beginning work either side of the bridge.

In response, a HES spokesperson said: “It is for the planning authority to decide what consents are needed for a particular proposal.”

HES guidance states that “key views to or from the historic asset or place” should be preserved.

Cathy Craig, CEO of Argyll & the Isles Tourism Cooperative (AITC), said any changes should be “carefully considered, with close collaboration between the local authority and the community, to ensure the character, beauty and visitor experience of the area are preserved”.

Nicholson said installing traffic lights would be detrimental to tourism because motorists would believe they had signal-sanctioned priority, making walking across the bridge more perilous.

These fears are well founded, believes Grant Baxter of Fife, who has spent 30 years as a chartered planner in Scottish local government.

“Somebody in a car or a bus or a lorry, [will think]: ‘I’ve now got the green light, there’s nobody stopping me.’”

Baxter added it had long been official Scottish government policy to prioritise pedestrians.

“The pedestrian is at the top of the road hierarchy and the car is at the bottom. Installing traffic lights is a 1980s-style intervention that completely fails for this location.”

In response to a request for comment, a Argyll and Bute spokesperson said: “We are currently developing a design for traffic lights that would support all users of the bridge.”

In a statement published on its website at the start of April, Argyll and Bute council said: “The council is taking steps to improve the safety of Clachan Bridge for those who use it by installing traffic lights, in the approach to the bridge. This action follows concerns from the public and the council, which is also supported by Police Scotland, regarding safety risks to bridge users; and more widely about the risk of a collision on the bridge cutting off access to and from the Isle of Seil.”

The council also apologised for delayed engagement with the community and set out its reasoning for not carrying out an impact assessment, concluding that “the proposal complies fully with the council’s statutory duties under the Islands (Scotland) Act 2018”.

Standing by the bridge, McKenzie and Nicholson suggested that cheaper, less intrusive measures could address any perceived risks without damaging the bridge’s historic and scenic setting. They said periodic trimming of foliage on the approach to bridge would improve sight lines for all concerned at a fraction of the cost of traffic lights.