Two-third rule than freight trains. On such tracks, the two-third rule applies to freight trains. The two-third rule means that the speed limit for a freight train is generally about two-thirds of the speed limit for an EMU. For example, the Dartford Loop Line has a speed limit of 60 mph for EMUs between Lee and Crayford. A freight train on this track is therefore limited to two-thirds of 60 mph, i.e. 40 mph. Two-third rule Two-third rule is British railway safety rule. For safety reasons, speed limits are imposed on trains running on a railway line. Many factors can affect the
One-third hypothesis theory. One-third hypothesis The one-third hypothesis (OTH) is a sociodynamic idea—advanced by Hugo O. Engelmann—that asserts that a group's prominence increases as it approaches one-third of the population and diminishes when it exceeds or falls below one-third of the population. As the one-third hypothesis was stated originally by Hugo O. Engelmann in a letter to the "American Sociologist" in 1967: "...we would expect that the most persistent subgroups in any group would be those which approximate one-third or, by similar reasoning, a multiple of [i.e., a power of] one-third of the total group. Being the most persistent, these groups also