第1章 企业成本费用的构成
The Keep-Right-Except-To-Pass Rule
Summary
As for the first question, it provides a traffic rule of keep right except to pass, requiring us to verify its effectiveness. Firstly, we define one kind of traffic rule different from the rule of the keep right in order to solve the problem clearly; then, we build a Cellular automaton model and a Nasch model by collecting massive data; next, we make full use of the numerical simulation according to several influence factors of traffic flow; At last, by lots of analysis of graph we obtain, we indicate a conclusion as follow: when vehicle density is lower than 0.15, the rule of lane speed control is more effective in terms of the factor of safe in the light traffic; when vehicle density is greater than 0.15, so the rule of keep right except passing is more effective In the heavy traffic. As for the second question, it requires us to testify that whether the conclusion we obtain in the first question is the same apply to the keep left rule. First of all, we build a stochastic multi-lane traffic model; from the view of the vehicle flow stress, we propose that the probability of moving to the right is 0.7and to the left otherwise by making full use of the Bernoulli process from the view of the ping-pong effect, the conclusion is that the choice of the changing lane is random. On the whole, the fundamental reason is the formation of the driving habit, so the conclusion is effective under the rule of keep left. As for the third question, it requires us to demonstrate the effectiveness of the result advised in the first question under the intelligent vehicle control system. Firstly, taking the speed limits into consideration, we build a microscopic traffic simulator model for traffic simulation purposes. Then, we implement a METANET model for prediction state with the use of the MPC traffic controller. Afterwards, we certify that the dynamic speed control measure can improve the traffic flow .
Lastly neglecting the safe factor, combining the rule of keep right with the rule of dynamical speed control is the best solution to accelerate the traffic flow overall.
Key words：Cellular automaton model Bernoulli process Microscopic traffic
simulator model The MPC traffic control
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第1章 企业成本费用的构成
Content
Content .............................................................................. 2 1. Introduction ...................................................................... 3 2. Analysis of the problem ........................................................... 3 3. Assumption ........................................................................ 3 4. Symbol Definition ................................................................. 3 5. Models ............................................................................ 4
5.1 Building of the Cellular automaton model .................................... 4
5.1.1 Verify the effectiveness of the keep right except to pass rule ......... 4
5.1.2 Numerical simulation results and discussion ............................ 5 5.1.3 Conclusion ............................................................ 8
5.2 The solving of second question .............................................. 8
5.2.1 The building of the stochastic multi-lane traffic model ................ 9 5.2.2 Conclusion ............................................................ 9
5.3 Taking the an intelligent vehicle system into a account ...................... 9
5.3.1 Introduction of the Intelligent Vehicle Highway Systems ............. 9 5.3.2 Control problem ....................................................... 9 5.3.3 Results and analysis................................................... 9 5.3.4 The comprehensive analysis of the result .............................. 10
6. Improvement of the model ......................................................... 11 6.1 strength and weakness ...................................................... 11
6.1.1 Strength ............................................................. 11
6.1.2 Weakness ............................................................. 11
6.2 Improvement of the model ................................................... 11
7. Reference ........................................................................ 13
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第1章 企业成本费用的构成
1. Introduction
As is known to all, it’s essential for us to drive automobiles, thus the driving rules is crucial important. In many countries like USA, China, drivers obey the rules which called “The Keep-Right-Except-To-Pass (that is, when driving automobiles, the rule requires drivers to drive in the right-most unless they are passing another vehicle)”.
2. Analysis of the problem
For the first question, we decide to use the Cellular automaton to build models, then analyze the performance of this rule in light and heavy traffic. Firstly, we mainly use the vehicle density to distinguish the light and heavy traffic; secondly, we consider the traffic flow and safe as the represent variable which denotes the light or heavy traffic; thirdly, we build and analyze a Cellular automaton model; finally, we judge the rule through two different driving rules, and then draw conclusions.
3. Assumption
In order to streamline our model we have made several key assumptions The highway of double row three lanes that we study can represent multi-lane freeways.
The data that we refer to has certain representativeness and descriptive Operation condition of the highway not be influenced by blizzard or accidental factors
Ignore the driver's own abnormal factors, such as drunk driving and fatigue driving
The operation form of highway intelligent system that our analysis can reflect intelligent system
In the intelligent vehicle system, the result of the sampling data has high accuracy.
4. Symbol Definition
i The number of vehicles t The time
3
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第1章 企业成本费用的构成
5. Models
By analyzing the problem, we decided to propose a solution with building a cellular automaton model.
5.1 Building of the Cellular automaton model
Thanks to its simple rules and convenience for computer simulation, cellular automaton model has been widely used in the study of traffic flow in recent years. Let xi(t)be the position of vehicle iat time t, vi(t) be the speed of vehicle
iat time t, pbe the random slowing down probability, and R be the proportion of trucks and buses, the distance between vehicle i and the front vehicle at time tis:
gapi?xi?1(t)?xi(t)?1, if the front vehicle is a small vehicle. gapi?xi?1(t)?xi(t)?3, if the front vehicle is a truck or bus.
5.1.1 Verify the effectiveness of the keep right except to pass rule In addition, according to the keep right except to pass rule, we define a new rule called: Control rules based on lane speed. The concrete explanation of the new rule as follow:
There is no special passing lane under this rule. The speed of the first lane (the far left lane) is 120–100km/h (including 100 km/h)；the speed of the second lane (the middle lane) is 100–80km8/h (including80km/h)；the speed of the third lane (the far right lane) is below 80km/ h. The speeds of lanes decrease from left to right.
Lane changing rules based lane speed control
If vehicle on the high-speed lane meets v?vcontrol, gapif(t)?min(vi(t)?1,vmax),
gapib(t)?gapsafe, the vehicle will turn into the adjacent right lane, and the speed of the vehicle after lane changing remains unchanged, where vcontrol is the minimum speed of the corresponding lane.
The application of the Nasch model evolution
Let Pd be the lane changing probability (taking into account the actual situation that some drivers like driving in a certain lane, and will not take
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第1章 企业成本费用的构成
the initiative to change lanes), gapif(t) indicates the distance between the vehicle and the nearest front vehicle, gapib(t) indicates the distance between the vehicle and the nearest following vehicle. In this article, we assume that the minimum safe distance gap safe of lane changing equals to the maximum speed of the following vehicle in the adjacent lanes.
Lane changing rules based on keeping right except to pass
In general, traffic flow going through a passing zone (Fig. 5.1.1) involves three processes: the diverging process (one traffic flow diverging into two flows), interacting process (interacting between the two flows), and merging process (the two flows merging into one) [4].
Fig.5.1.1 Control plan of overtaking process
(1) If vehicle on the first lane (passing lane) meets gapif(t)?min(vi(t)?1,vmax) and gapib(t)?gapsafe, the vehicle will turn into the second lane, the speed of the vehicle after lane changing remains unchanged. 5.1.2 Numerical simulation results and discussion
In order to facilitate the subsequent discussions, we define the space occupation rate asp?(NCAR?3?Ntruck)/3?L, whereNCAR indicates the number of
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