Back in February, we wrote about a proposed device called the LightLane that would create a laser projected mobile bike lane for cyclists navigating the streets at night. Now Streetsblog directs us to a conceptual design for a low tech, daytime version. Conceived as part of the Power to the Pedal Competition, the Contrail – named for its similarity to condensation trails left by aircraft – would give bicyclists the ability to leave a chalk trail across the concrete to effectively “carve out” an ad hoc bike lane on any street and create a lasting visual record of their travels [...]