The TCS London Marathon is one of the hundreds of marathons around the world that feature a blue line around the course. This got runABC reporter Alan Newman thinking... 

What's the history of this feature? Does it show the runners the correct route? Does it mark the shortest possible route? Is it always a blue line? Is it always a single, solid line? And what's it made of, so that it can be easily removed?

Let's start at the beginning. The first record of a marathon route marking line being used was at the Melbourne Olympics in 1956 – and it was green! Some of it could still be seen for more than 25 years. Its stated purpose was to assist competitors from all nations to follow the route in training and competition. By the time of the Montreal Olympics in 1976, the line had become blue and this has remained the standard colour to differentiate between white road markings and yellow lines that have become synonymous with parking restrictions.

It is often said that following the blue line means running the shortest distance from start to finish, as this is where the course is measured. Not quite so, according to 1982 London Marathon champion Hugh Jones, an expert international course measurer and Secretary of the Association of International Marathons (AIMS) since 1996. 

Jones was involved in painting the blue line that was first used for the 1985 London Marathon and had to incorporate some 'tweaks' to avoid it causing problems when the three separate starts merged and also to give suitable clearance at drink stations, on the tighter corners, and more recently to prevent runners being directed through ‘mist stations’ they may wish to avoid.

Jones said: "If runners wish to take drinks or run under the cooling spray they should have to slightly depart from the blue line to do so." In this excellent blog on the subject, Jones reckons the London Marathon blue line is likely to be 70 metres over distance for the reasons stated. 

Over the years, the solid blue line has become a broken line to save costs and for a better appearance, as any imperfections in laying the solid line are immediately obvious in a TV long shot. And it is usually a single line, although several events where Adidas was the sponsor have used three, thinner lines for commercial reasons! 

Finally, the lines are conventional road marking paint and are laid and subsequently removed by specialist trucks using high-pressure hoses and a solvent, usually as soon as the tail-enders pass through and before the paint has really had the chance to 'take hold'.

So now you know why your next marathon will have a probably broken blue line for the entire route.   

Image courtesy Berlin Marathon on Facebook