This SAE Recommended Practice provides guidelines for procedures and practices used to obtain and record measurements and to analyze the results of the critical speed method. It is for use at accident sites using manual or electronic measurements. The method allows for many unique factors and the recommended procedure will permit a consistent use of the method in order to reduce errors and uncertainty in the results. The results from the critical speed formula should always, when possible, be compared to other accident reconstruction methodologies. When different accident reconstruction methods are used, the uncertainty of each method should be analyzed and presented.