I have learned these in undergraduate classes, but later I did not do this direction when I was doing scientific research, and I forgot it after a long time. Recently, I did an internship related to signal control, so I had to pick it up, or I would be laughed at. The content mainly refers to this article , which is well written and comprehensive. Next, I will summarize and record these concepts.
1. Phases and Phases
Definition of phase : One or several traffic streams obtain the exact same signal light color display at any moment, then the continuous timing of obtaining different light colors (green light, yellow light, all red) is called a signal phase. To put it simply, a phase is a right of way. For example, for a typical four-phase intersection, first go straight north-south, then turn left after north-south, then go straight east-west, then turn left east-west. The vehicle obtains the right of way, and the right of way is given to other directions during other periods of a cycle. This is a phase.
Definition of phase : The "right of way" at the intersection is allocated to each phase in turn, and each conversion of the "right of way" is called a signal phase, and several times of handover of the right of way in a signal cycle are several signal phases. To put it simply, a signal stage is a period of time when the signal timing does not change. For a typical four-phase intersection, the time period when the north-south straight line is green and the other direction is red is the period, and the period is the concept of a period of time.
The picture in the article shows the difference between phase and aspect very well. A phase is a right of passage, and a phase is a period of time with constant timing.
2. Lap phase
An overlapping phase is one or more traffic streams that start/end another phase in advance before the end of a certain phase (or in other words, one or more traffic streams that end/start the previous phase before a certain phase starts). Still take the four-phase intersection as an example, first turn north-south and go straight, then turn north-south and turn left, then turn east-west and go straight, then turn east-west and turn left. Now suppose we make a slight modification, first let the north-south go straight, then go straight to the south, the light is still green, go straight to the north, turn red, and then let the north-south turn left at the same time, and then only let the north-south turn left, the latter is unchanged, let the east and west go straight, and then put Things turn left. At this time, we found that the south side goes straight across the first and second phases of the original four phases, and this phase becomes an overlapping phase. Since the overlapping phase is generally short, it can be considered as a total of four phases instead of a single phase. phase, plus an overlapping phase. Of course, it can be considered as five phases. It is also easy to understand when it is necessary to overlap the phase. There are many through vehicles in the south, and it is more important, and there are not many left-turning vehicles in the north, so an overlap phase can be set. At this time, going straight to the south is also considered a permitted aspect , because it is not the exclusive right of way for going straight at this time, but will conflict with turning left to the north. In the same way, if only going straight north-south before, then going straight north-south is a protective aspect .
3. Key lane group
The key lane group is the traffic flow combination with the largest sum of flow ratios in a cycle. That is, the combination of traffic flow that is most likely to cause secondary queuing. For example, for the figure below, the key lane group is the sum of the flow ratios of a certain traffic flow in phase 1 + a certain traffic flow in phase 2 + a certain traffic flow in phase 3, and these traffic flows are exactly one cycle.
4. References
Dahua Letter Control | Phase & Phase: https://www.sohu.com/a/406651193_389742
For details, see the article in the link. This article can be used as a reading supplement to help you understand quickly.