There are standard roadway maintenance practices and regulations that departments must abide by to create a safe operating environment. Friction is the resisting force of motion between two surfaces when they are in contact. The friction generated between any two surfaces is important in reconstruction since friction converts kinetic energy to heat, noise and deformation and damage of materials. Friction analysis can determine the speed of a car. A record of these conditions helps establish whether slippery or wet roads affected the accident.
Road conditions are critical to establishing the drag and speed at the time of the accident.
Many people overestimate their seeing ability at night and very often the headlights are insufficient to reveal potential collisions in time for the operator to avoid them. The materials used in the construction of roadway surfaces often reflect light in different ways. The road surface has a significant effect on the drivers recognition of objects and vehicles on the road. Ambient lighting, headlights, moisture conditions and other factors make up a complex set of conditions that determine whether an object or roadway geometry is visible. Pedestrians are often hit at night because the road is not adequately lit or the victim is wearing dark clothing.