Abstract: A road surface friction detector for use in a vehicle. The detector provides information regarding the integrity of a road surface to an operator of the vehicle. The detector is made up of three main parts, a sensor unit, a display unit and a microprocessor unit. The sensor unit is made up of a first sensor unit and a second sensor unit. The first sensor unit contains a first light source which directs light at the road surface to be reflected back to a first light receiver. The amount of light that returns to the first light receiver corresponds to various conditions on the road. The second sensor unit is made up of a second light source, second light receiver and a reflective element. The second light source directs light at the reflective element which is located between the second light source and the road. The light from the second light source is then reflected off of the reflective element to the second light receiver.