THE more cyclists on the road, the lower the risk of collisions.

That was the finding recently in the first American study to examine the relationship between cycling rates and safety, and it appears to correlate with patterns already observed in Europe, Canada and Australia.

It might seem counter-intuitive but repeated studies have found that the number of collisions per cyclist tends to decrease the more people take up cycling; the so-called "safety in numbers" effect.

The theory goes that the more drivers expect to encounter cyclists on the road the more cautious they become.

The latest study, conducted by civil engineers at the University of Colorado, focuses on Boulder, a city with one of the highest cycling rates in the US at 12 per cent of journeys. (For comparison, the Scottish Government wants 10 per cent of journeys to be made by bike by 2020, from one per cent in 2008.)

It compared the number of motorist-cyclist collisions at traffic-lighted junctions against both the volume of total traffic passing through the crossroads and the number of cyclists. It was discovered that the junctions with the lowest volume of cyclists per day - fewer than 200 - were "high-risk" zones where cyclists were up to six time more likely to be struck by a vehicle than junctions with more than 600 cyclists per day.

Wesley Marshall, an assistant professor of civil engineering and co-author of the study, said: "Other studies have hypothesized that when drivers expect to see a significant number of bicyclists on the street, their behavior changes. They are more likely to look over their shoulder for a bicyclist before taking a right turn."

Prof Marshall added that "cities with a high level of bicycling are not just safer for cyclists but for all road users".

In Australia, when the number of cyclists in Western Australia almost doubled from 220,000 in 1982 to 400,000 in 1989 - an increase of 82 per cent - the number of cyclists killed or seriously injured rose by only 22 per cent, from 123 to 150.

Even more dramatic changes emerged in Finland where a national drive to promote cycling saw the number of journeys taken by bike increase by 72 per cent against a 75 per cent drop in cyclist deaths.

These trends have bolstered those who argue against the introduction of a compulsory helmet law, a policy that has been shown to deter people from taking up cycling. So what has been the trend in Scotland?

According to the latest road casualty statistics for Scotland, there were 882 pedal cyclist casualties in 2013. This included 148 people who were seriously injured and 13 fatalities.

The same report states that the number of cyclists on Scotland's roads has grown by 24 per cent in the past 10 years, yet the 2003 figures are pretty similar: 800 cyclist casualties, 123 seriously injured and 14 fatalities. On that basis it appears Scotland is conforming to the international trend and, if the Scottish Government can meet its cycling target, Scotland's roads should be safer for everyone by 2020.