It takes time to hire an accident reconstructionist. Care should be taken in order to preserve evidence that can be short-lived. Witness and party memories fade over time. Skid marks fade over time. Snow removal or another accident can alter, add, or change gouge marks in the pavement. Take pictures, measurements, and field sketches of road width, the number of lanes, location of curves, permanent fixtures, skid marks. Photograph close up and far away the location of unmoved debris: this is extremely critical. Remember, however, your sketch could end up in evidence at trial. Do not write anything that you do not want others to read.