In 2009, blue lights were installed at the end of platforms on Tokyo's Yamanote railway line to reduce the incidence of suicide. As a result of the success of these lights (suicides fell by 74 percent at stations where the blue lights were installed), similar colored lighting was installed at Gatwick Airport train platforms.
Although rarely found in the natural world apart from bodies of water and sky, blue is the color most preferred by people everywhere, and is a rare example among colors in having a similar meaning around the world. Universally, blue imparts trust, strength, serenity, and protection.
Although black and white photography is often favored when the artist's aim is to focus on design and structure without the distraction of color, the color blue also works well in helping to highlight the intricacies of the tree while also conveying the strength, serenity, and protection it provides.