Block Mechanism of Left-turned Flow at Signal-Controlled Roundabout

The "left-turn with two stops" control method, being an organically combined method between signal control and roundabouts has been greatly applied in some of the Chinese cities, resulting in certain traffic and social efficiency. In the meanwhile, because of the short time in putting forward the theory, it appears, to some extent, immature up till now, especially that the essential problem concerning the block mechanism of signal-controlled roundabout influences the left-turned flow still needs further discussion from the point of theory. It is from the above background that this text gives it good study to the block types and emission regularities resulted from the left-turned vehicles at signal-controlled roundabouts, trying to make a quantizing calculation about such retardation in which delay is taken as objective function and to obtain the calculative formula for average delay of individual left-turned vehicle at signal-controlled roundabouts.