An ERD file is a data file used by various programs used to analyze the profiles of roads, such as ProVAL and EP (Engineering Plotter). It may contain road profiles, vehicle simulation output, vehicle test data, and measurements of vehicle component behavior.

The ERD format consists of two parts: Header - Stores information about how post-processing tools should read the data. Data - Stores numbered data, which may be in text or binary form. If the data part is stored in text form, both the header and data parts are contained in one ERD file. If the data part is stored in binary form, the header part is stored as plain text in an ERD file separate from the data part, which is stored in a .BIN file. Both the ERD and BIN file must bear the same name and be placed in the same folder in order to be read by a program. The ERD format was developed by the Engineering Research Division (ERD) of the University of Michigan Transportation Research Institute (UMTRI). It was originally only used by RoadRuf, a road profile analysis program. However, it was eventually adopted as a standard data format for analyzing and measuring road profiles.