CN108765988B - Intersection signal dynamic optimization method for internet data - Google Patents
Intersection signal dynamic optimization method for internet data Download PDFInfo
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Abstract
The invention discloses an internet data-oriented intersection signal dynamic optimization method, which mainly comprises three stages of basic timing principle design, internet data processing and timing scheme generation: the basic timing principle design mainly gives basic parameters such as a phase division principle, the shortest pedestrian time and the like; the internet data processing is mainly used for calculating a traffic operation index and an operation state grade for signal optimization on the premise that the average travel speed of each direction of the intersection is provided only by the internet; the timing scheme generation is based on the set basic principle and the estimated traffic running state, the period calculation and the phase time design are carried out, the complete signal timing scheme of the intersection is finally obtained, and dynamic optimization is continuously carried out according to new data. The invention provides an Internet data application-oriented method on the premise that the traditional detection information is lacked at the intersection, so that the efficiency of a real-time timing scheme of the intersection signal lamp is improved, and the fluctuation and the accident condition of the traffic demand are effectively coped with.
Description
Technical Field
The invention relates to the technical field of urban intelligent traffic systems, in particular to a crossing signal dynamic optimization method for internet data.
Background
In the face of the rapidly increasing urban motor vehicle holding capacity and the travel demand of residents, the urban traffic supply capacity is far smaller than the traffic demand increase, in addition, accidents occur frequently, the traffic jam of small and medium-sized cities gradually begins to aggravate, and part of core areas are easy to cause regional jam or local traffic paralysis, especially in the morning and evening rush hours, afternoon before holidays leave holidays, large activities and the like. When urban road network construction, traffic engineering design and infrastructure construction tend to be stable, the first-choice countermeasures for further improving traffic operation efficiency are concentrated on signal control optimization. At present, under the influence of urban economy, society and other factors, the detection of traffic information in small and medium-sized cities has the characteristics of few detection points, incomplete information, difficult control of data quality and the like, so that dynamic optimization of a crossing signal timing scheme has a plurality of difficulties.
The existing urban intersection signal dynamic optimization method is mainly summarized into the following categories: (1) timing control mainly adopts a preset period and a preset split ratio, is suitable for the condition of relatively stable and regular traffic flow, mostly takes the traffic flow as a model optimization input parameter, and solves a control target according to the pre-estimated vehicle average delay, for example, the Webster method and the Miller method are the most commonly used optimization methods. The method mainly depends on the acquired historical traffic flow information and does not consider the fluctuation condition of the traffic flow demand. (2) The induction control is that detectors are usually installed in half or all directions of the intersection to detect the arrival condition of the vehicle in real time, and whether the green light time of the current phase is prolonged by one step length or is terminated is judged according to the arrival condition. The method is mainly suitable for the condition that the traffic flow difference in each direction of the intersection is large, the traffic flow information needs to be detected in real time, the situations of arrival, delay and queuing of traffic flows in other directions are not considered when the green light time in one direction is prolonged, and meanwhile, the method cannot be suitable for a coordination control scene without a fixed period concept. (3) The self-adaptive control is to regard the traffic system as an uncertainty system, establish the relationship between various parameters and a signal timing scheme by detecting multiple traffic parameters such as flow, delay, queuing length, parking times and the like in real time, so as to solve the dynamic optimization adjustment of an optimal or suboptimal control scheme, such as TRANSYT, SCOOT, SCATS, Synchro, OPAC and other control systems or methods. The method can well adapt to the fluctuation situation of traffic demand, calculates a good timing scheme according to an expected control target, but has more detectors and data sources which need to be installed, more complex models, more calculation and time resources, and a plurality of limitations on the application range.
With the rapid development and great popularization of the internet plus technology, the method provides rich, comprehensive, space-time continuous and individualized traffic running state information for the urban traffic network, and is also an important basis for optimizing intersection signal timing. The traditional signal timing optimization method mostly depends on traffic flow information of intersections and cannot directly apply traffic running states provided by the Internet.
Disclosure of Invention
The invention aims to overcome the defects and shortcomings of the prior art, provides an internet data-oriented intersection signal dynamic optimization method, researches the timing characteristics of intersection signals, establishes a rule-based single intersection signal dynamic control method only depending on limited and incompletely accurate data resources provided by the internet under the condition of no other additional detection information, realizes quick solution, further improves the utilization efficiency of intersection space-time resources, responds to traffic demand change and unexpected traffic events, slows down urban traffic jam to a certain extent, and reduces travel cost.
The purpose of the invention is realized by the following technical scheme: an intersection signal dynamic optimization method facing internet data comprises the following steps:
s1, designing a basic timing principle to reduce time-space conflict and ensure pedestrian crossing safety during intersection signal control;
s2, judging whether the current time is an integral multiple of the signal optimization interval, if so, processing the acquired Internet data into a data format required by signal optimization, and calculating a traffic operation index and an operation condition grade; otherwise, go directly to step S3;
s3, judging whether signal optimization is needed at the current moment according to the appointed conditions, and if so, turning to the step S4; otherwise, jumping to step S6;
s4, dynamically optimizing the signal period, and performing period optimization according to the calculated traffic operation index and the operation condition grade on the basis of the current signal timing of the intersection;
s5, after the period is set, the split ratio of each phase is optimized according to the fluctuation of the traffic operation index and the operation condition grade, and a complete signal timing scheme is formed;
and S6, updating the time, and sending the original signal timing scheme or the newly generated timing scheme to the signaler for implementation.
Preferably, in step S2, the processing of the acquired internet data into a data format required for signal optimization includes the following steps:
firstly, defining a signal optimization interval as a time interval of a dynamic optimization primary signal timing scheme, excluding phase and phase sequence design, and recording as T1And is an integer multiple of the period; and calculating and storing the average value in the current interval based on the signal optimization intervalThe average stroke speed;
secondly, for the average travel speed of the current signal optimization interval, data preprocessing is carried out, wherein the data preprocessing comprises data restoration and smoothing.
Finally, defining the grade of traffic running conditions according to the processed average travel speed of each inlet direction and steering type of the intersection, and dividing the grade into three grades of smoothness, slowness and congestion;
the basic principle of the grade division of the traffic running condition is as follows:
[4]when v (k) is not less than 0.67vfMeanwhile, the grade of the traffic running condition is smooth and is marked as 0; wherein v (k) represents the mean travel speed acquired at the k-th signal optimization interval, if no data is acquired
Instead of this, the user can,
a predicted average travel speed representative of a current k-th signal optimization interval; v. offRepresenting the traffic flow travel speed in a free flow state on a road section;
[5]when 0.33vf≤v(k)＜0.67vfMeanwhile, the grade of the traffic running condition is slow and is marked as 1;
[6]when v (k) < 0.33vfIn time, the grade of the traffic running condition is congestion and is marked as 2;
meanwhile, a traffic operation index, which is defined as a ratio of the free flow speed to the actual average travel speed, is calculated.
Specifically, when no data is collected in the current signal optimization interval, the data restoration needs to perform smoothing processing by using historical data, and the algorithm method of the restored average travel velocity meter in the current signal optimization interval is as follows:
in the formula (I), the compound is shown in the specification,
a predicted average travel speed representative of a current k-th signal optimization interval; v (k-1) is the average travel speed actually acquired in the k-1 signal optimization interval;
representing the predicted value of the average travel speed in the optimization interval of the k-1 signal; alpha represents a smoothing coefficient, and parameter calibration is performed by a least square method.
Specifically, the smoothing process means that when the average travel speed of the current signal optimization interval exceeds the actual possible speed range, the maximum free flow speed is required to be used instead.
Preferably, in step S3, if the following rule is satisfied, the activation signal optimization is required:
[4]current time of day
When the current is over;
[5] when the levels of the traffic running conditions corresponding to the phases are not completely the same;
[6]when in use
When the current is over;
in the formula, n is an integer; mod (nT)1,TC) A remainder part representing a numerical value obtained by dividing the first term by the second term in parentheses; t isCRepresenting the signal period adopted by the intersection at the current moment; tti (k) represents the traffic running index average for all phases of the current signal optimization interval; beta represents the control expectation of the user on the operation index.
Specifically, beta is less than or equal to 0.2.
Preferably, in step S4, the dynamic optimization of the signal period depends on the signal period, the traffic operation index and the operation condition level at the current time, and is specifically calculated as follows:
[1] during peak periods, the formula for updating the period is as follows:
TC(k+1)＝max(min(TC′(k+1),Tmax),Tmin) (2)
in the formula, TC(k +1) represents a signal period value of the (k +1) th signal optimization interval;
optimizing an identification bit for the kth signal when the operating condition grade of the ith phase is smooth, wherein the value is 1 if the operating condition grade of the kth phase is smooth, and the value is 0 if the operating condition grade of the kth phase is smooth; t isΔA step value adjusted once for each phase;
optimizing an identification bit for the kth signal at an interval with the ith phase operating condition grade being congestion, wherein if the operation condition grade is congestion, the value is 1, and if not, the operation condition grade is 0; i represents the number of phases; eta indicates that the operating conditions of the phases are all slow and
if so, the value is 1, otherwise, the value is 0; max (,) represents taking the function of both maxima; min (,) represents taking the minimum function of both; t ismaxAnd TminRespectively representing the maximum value and the minimum value of the signal period allowed to be adopted by the intersection; the early peak period refers to that the working hours specified by the local people government are delayed by one hour before and one hour after each working hour; the late peak period refers to that the off-duty time specified by the local people government is delayed by one hour before and one hour after work;
[2] during off-peak periods, the formula for periodic updates is as follows:
TC(k+1)＝max(min(TC″(k+1),Tmax),Tmin) (4)
in the formula (I), the compound is shown in the specification,
an identification bit with the kth signal optimization interval and the ith phase operation condition grade being slow is provided, if the identification bit is slow, the identification bit is 1, otherwise, the identification bit is 0;
all the operation condition grades of all the phases are smooth and meet
If so, it is 1, otherwise, it is 0.
Preferably, in step S5, after the period is set, a complete signal timing scheme is formed, wherein the yellow light time is determined according to the characteristics of the city driver and the intersection characteristics; the full red time is determined according to the shape of the intersection and the driving speed of a driver at the intersection;
and optimizing the green time of each phase, wherein the specific calculation method comprises the following steps:
[1] during peak hours, the green time for the ith phase is as follows:
[2] during off-peak hours, the green time for the ith phase is as follows:
and (4) checking the optimized green light time according to the formula (6) and the formula (7) to ensure the equivalent relation of the period, the green light time, the yellow light time and the full red time.
Further, the green time of the last phase I is corrected, and the specific formula is as follows:
in the formula (I), the compound is shown in the specification,
representing the yellow light time of the (k +1) th signal optimization interval and the ith phase, and taking the same phase and not less than 3 s;
indicating the full red time for the ith phase.
Preferably, in step S1, the basic principle of signal timing includes the following:
(4) the premise of the design of the left-turn special phase is that a special left-turn lane is provided and any one of the following conditions is met;
a) when the left-turn single lane flow is 100-;
b) when the left-turn single lane flow exceeds 200 pcu/h;
c) traffic accidents occur 5 times or more per year in three years on average, and accident cause analysis can avoid the accident intersections by setting a special left-turn phase;
d) the death traffic accidents occur 1 time or more per year in three years on average, and the accident cause analysis can avoid the intersection where the accident occurs by setting a special left-turn phase;
(5) the premise of adopting single import release is that any one of the following conditions is met:
a) the difference of the flow of the single lane for straight and left turn in the opposite direction is not less than 100-200 pcu/h; and the difference of the flow of the single lane for straight and left turn in the same direction is not more than 100-200 pcu/h;
b) for intersections without a left-turn special lane, traffic accidents occur 5 times or more per year in three years on average, and the accident reason analysis can avoid the intersections with the accidents by setting a single-inlet release phase; or the death traffic accidents occur 1 time or more per year in three years on average, and the accident reason analysis can avoid the intersection where the accidents occur by setting a single-inlet release phase;
(6) the principle of setting the upper and lower limits of the period refers to the following requirements:
a) the maximum period consideration factors comprise the psychological bearing capacity of a driver and the distance between the upstream road section and the downstream road section, so that the road section overflow caused by overlarge period is prevented;
b) the minimum period needs to meet the safe crossing time of the pedestrians in all directions;
for intersections without detectors, the internet cannot provide the traffic flow involved in the process, and the traffic flow is obtained through manual investigation and used as historical experience information to design the phase and the phase sequence.
Compared with the prior art, the invention has the following advantages and beneficial effects:
(1) the invention provides an Internet data application-oriented method on the premise that the traditional detection information is lacked at the intersection, so that the efficiency of a real-time timing scheme of the intersection signal lamp is improved, and the fluctuation and the accident condition of the traffic demand are effectively coped with.
(2) The invention respectively provides customized optimization targets aiming at the traffic demand and the congestion condition of the difference between the peak time and the off-peak time, respectively realizes the balance of the running condition grades in all directions of the intersection at the peak time and the off-peak time, and maximally reduces the waste of space-time resources in the directions.
(3) The intersection dynamic optimization method provided by the invention does not depend on traffic flow data required by the traditional timing method, can timely, accurately and reliably estimate the signal timing scheme according to the traffic operation index and the operation condition grade obtained by the data processing algorithm, and can provide beneficial help for traffic management and control, traffic guidance and travel planning.
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FIG. 1 is a schematic flow diagram of an example method.
Detailed Description
The present invention will be described in further detail with reference to examples and drawings, but the present invention is not limited thereto.
Example 1
On the premise that only internet traffic running state information exists at an intersection, and under the scene that a traditional signal timing strategy cannot directly apply the data, a single intersection signal real-time optimization method facing internet data (average travel speed) is provided. The intersection signal dynamic optimization method adopts a periodic optimization method, which not only meets the signal timing optimization requirement of the intersection, but also can consider the constraint requirement that the period between adjacent intersections is kept consistent when trunk road or area coordination control is required in the future. In the initial condition setting, basic criteria and parameter requirements of signal timing optimization are provided for any given optimized intersection; in the period optimization, whether the intersection is an intersection in a coordination network or an independent intersection is distinguished, and stepping dynamic optimization is carried out on the basis of the existing signal period; in phase optimization, symmetrical release or import single release is designed based on the difference of the running states of the same-direction traffic and opposite-direction traffic; in phase green light time optimization, the green light time of each phase is dynamically optimized in real time based on the traffic running state of the current phase and the states of other phases, and the air release and congestion imbalance are reduced.
An internet data-oriented intersection signal dynamic optimization method mainly comprises three stages of basic timing principle design, internet data processing and timing scheme generation: the basic timing principle design mainly gives basic parameters such as a phase division principle, the shortest pedestrian time and the like; the internet data processing is mainly to eliminate gross error of data and repair missing data on the premise of only average travel speed of each direction of the intersection provided by the internet, and calculate traffic operation index and operation state grade for signal optimization; the timing scheme generation is based on the set basic principle and the estimated traffic running state, the period calculation and the phase time design are carried out, the complete signal timing scheme of the intersection is finally obtained, and dynamic optimization is continuously carried out according to new data.
The method specifically comprises the following steps:
s1, designing a basic timing principle, and mainly meeting the requirements of reducing time-space conflicts and ensuring the safety of pedestrian crossing during intersection signal control.
S2, judging whether the current time is an integral multiple of the signal optimization interval, if so, processing the acquired Internet data into a data format required by signal optimization, and calculating a traffic operation index and an operation condition grade; otherwise, go directly to step S3;
the mainstream internet in China can provide traffic data which mainly comprises average travel speed, and indexes such as traffic operation indexes and congestion levels evolved according to the speed. Lack of information acquisition for all vehicles in transit does not provide accurate sample rate information. The embodiment preferably uses the average crossing travel speed provided by the internet as the only reliable data source for subsequent signal timing optimization.
First, defining a signal optimization interval as a time interval for dynamically optimizing a one-time signal timing scheme (excluding phase and phase sequence design), denoted as T1In seconds and is an integer multiple of the period. And on the basis of the signal optimization interval, calculating and storing the average travel speed in the current interval.
Secondly, for the average travel speed of the current signal optimization interval, data preprocessing is carried out, wherein the data preprocessing comprises data restoration and smoothing.
The data restoration is that when no data is collected in the current signal optimization interval, historical data needs to be adopted for smoothing, and the algorithm method of the restored average travel speed meter in the current signal optimization interval comprises the following steps:
in the formula (I), the compound is shown in the specification,
a predicted average travel speed (unit: km/h) representing the current kth signal optimization interval; v (k-1) is the average travel speed (unit: km/h) actually acquired in the k-1 signal optimization interval;
representing the predicted value (unit: km/h) of the average travel speed in the optimization interval of the kth-1 signal; alpha stands for smoothingAnd (4) calibrating parameters by a least square method.
The smoothing process means that when the average travel speed of the current signal optimization interval exceeds the actual possible speed range, the maximum free flow speed is required to be used for replacing.
And finally, defining the grade of the traffic running condition according to the processed average travel speed of each inlet direction and steering type of the intersection, and dividing the grade into three grades of smooth, slow and congested. Meanwhile, a traffic operation index is calculated, which is defined as the ratio of the free flow speed to the actual average travel speed.
The basic principle of the grade division of the traffic running condition is as follows:
[7]when v (k) is not less than 0.67vfAnd in time, the grade of the traffic running condition is smooth and is marked as 0. Where v (k) represents the mean travel speed (in km/h) acquired at the kth signal optimization interval, if no data is acquired
Replacing;
[8]when 0.33vf≤v(k)＜0.67vfIn time, the traffic operating condition is slow, and is marked as 1. Wherein v isfRepresenting the traffic flow travel speed (unit: km/h) in a free flow state on a road section;
[9]when v (k) < 0.33vfIn time, the grade of the traffic running condition is congestion and is marked as 2;
s3, judging whether signal optimization is needed at the current moment, and if so, turning to the step S4; otherwise, the process jumps to step S6.
If the following rule is satisfied at the same time, the start signal optimization is required:
[7]current time of day
When the current is over;
[8] when the levels of the traffic running conditions corresponding to the phases are not completely the same;
[9]when in use
When the current is over;
in the formula, n is an integer; mod (nT)1,TC) A remainder part representing a numerical value obtained by dividing the first term by the second term in parentheses; t isCRepresenting the signal period adopted by the intersection at the current moment; tti (k) represents the traffic running index average for all phases of the current signal optimization interval; beta represents the user's control desire for the operational index, and is typically ≦ 0.2.
And S4, dynamically optimizing the signal period, and performing period optimization according to the calculated traffic operation index and the operation condition grade on the basis of the current signal timing of the intersection.
In step S4, the dynamic optimization of the signal period mainly depends on the signal period, the traffic operation index, and the operation status level at the current time, and is specifically calculated as follows:
[1] during peak periods, the formula for updating the period is as follows:
TC(k+1)＝max(min(TC′(k+1),Tmax),Tmin) (2)
in the formula, TC(k +1) represents a signal period value (unit: s) of the (k +1) th signal optimization interval;
optimizing an identification bit for the kth signal when the operating condition grade of the ith phase is smooth, wherein the value is 1 if the operating condition grade of the kth phase is smooth, and the value is 0 if the operating condition grade of the kth phase is smooth; t isΔStep values adjusted once for each phase, in seconds;
optimizing an identification bit for the kth signal at an interval with the ith phase operating condition grade being congestion, wherein if the operation condition grade is congestion, the value is 1, and if not, the operation condition grade is 0; i represents the number of phases; eta indicates that the operating conditions of the phases are all slow and
if so, the value is 1, otherwise, the value is 0; max (,) represents taking the function of both maxima; min (,) represents taking the minimum function of both; t ismaxAnd TminRespectively representing the maximum value and the minimum value of the signal period allowed to be adopted by the intersection. The early peak period refers to that the working hours specified by the local people government are delayed by one hour before and one hour after each working hour; the late rush hour is one hour delay before and after the off-duty time specified by the local people's government.
[2] During off-peak periods, the formula for periodic updates is as follows:
TC(k+1)＝max(min(TC″(k+1),Tmax),Tmin) (4)
in the formula (I), the compound is shown in the specification,
an identification bit with the kth signal optimization interval and the ith phase operation condition grade being slow is provided, if the identification bit is slow, the identification bit is 1, otherwise, the identification bit is 0;
all the operation condition grades of all the phases are smooth and meet
If so, it is 1, otherwise, it is 0.
And S5, after the period is set, optimizing the green signal ratio of each phase according to the fluctuation of the traffic operation index and the operation condition grade to form a complete signal timing scheme.
In step S5, on the premise of cycle optimization, optimization of the split ratio of each phase is performed, and the split ratio of each phase is optimized mainly depending on the fluctuation of the traffic operation index and the level of the operation condition. The yellow light time is determined according to the characteristics of urban drivers and the characteristics of intersections and is usually not less than 3 s; the full red time depends on the shape of the intersection and the usual driving speed at the driver's intersection.
After the period is set, a complete signal timing scheme is formed.
The optimized time of the invention is mainly the green time of each phase, and the specific calculation method is as follows:
[1] during peak hours, the green time for the ith phase is as follows:
[2] during off-peak hours, the green time for the ith phase is as follows:
in the step S5, the optimized green time is checked according to the formula (6-7), and the equivalence relation among the period, the green time, the yellow time, and the full red time is ensured. In the invention, the green time of the last phase I is corrected, and the specific formula is as follows:
in the formula (I), the compound is shown in the specification,
representing the yellow light time of the (k +1) th signal optimization interval and the ith phase, and taking the same phase and not less than 3 s;
indicating the full red time for the ith phase.
And S6, updating the time, and sending the original signal timing scheme or the newly generated timing scheme to the signaler for implementation.
In step S1, the basic principle of signal timing mainly includes the following:
(7) the premise of the design of the left-turn special phase is that a special left-turn lane is provided and any one of the following conditions is met;
a) when the left-turn single lane flow is 100-;
b) when the left-turn single lane flow exceeds 200 pcu/h;
c) traffic accidents occur 5 times or more per year in three years on average, and accident cause analysis can avoid the accident intersections by setting a special left-turn phase;
d) the death traffic accidents occur 1 time per year or more in three years on average, and the accident reason analysis can avoid the intersection where the accident occurs by setting a special left-turn phase.
(8) The premise of adopting single import release is that any one of the following conditions is met:
a) the difference of the flow of the single lane for straight and left turn in the opposite direction is not less than 100-200 pcu/h; and the difference of the flow of the single lane for straight and left turn in the same direction is not more than 100-200 pcu/h;
b) for intersections without a left-turn special lane, traffic accidents occur 5 times or more per year in three years on average, and the accident reason analysis can avoid the intersections with the accidents by setting a single-inlet release phase; or the death traffic accidents occur 1 time per year or more in three years on average, and the accident reason analysis can avoid the intersection where the accidents occur by arranging the single-inlet release phase.
(9) The principle of setting the upper and lower limits of the period is suggested to refer to the following requirements:
a) the maximum period is mainly based on the consideration of factors such as the psychological bearing capacity of a driver, the distance between an upstream road section and a downstream road section (the phenomenon that the road section overflows due to overlarge period) and the like, and the maximum period of the medium and small-sized cities is recommended to be not more than 180 s;
b) the minimum period is mainly to meet the safe crossing time of the pedestrians in all directions.
For intersections without detectors, the internet cannot provide the traffic flow involved in the process, and the traffic flow is obtained through manual investigation and used as historical experience information to design the phase and the phase sequence.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.
Claims (8)
1. An internet data-oriented intersection signal dynamic optimization method is characterized by comprising the following steps:
s1, designing a basic timing principle to reduce time-space conflict and ensure pedestrian crossing safety during intersection signal control;
s2, judging whether the current time is an integral multiple of the signal optimization interval, if so, processing the acquired Internet data into a data format required by signal optimization, and calculating a traffic operation index and an operation condition grade; otherwise, go directly to step S3;
s3, judging whether signal optimization is needed at the current moment according to the appointed conditions, and if so, turning to the step S4; otherwise, jumping to step S6;
s4, dynamically optimizing the signal period, and performing period optimization according to the calculated traffic operation index and the operation condition grade on the basis of the current signal timing of the intersection;
s5, after the period is set, the split ratio of each phase is optimized according to the fluctuation of the traffic operation index and the operation condition grade, and a complete signal timing scheme is formed;
s6, updating time, and sending the original signal timing scheme or the newly generated timing scheme to the signal machine for implementation;
in step S4, the dynamic optimization of the signal period depends on the signal period, the traffic operation index, and the operation status level at the current time, and is specifically calculated as follows:
[1] during peak periods, the formula for updating the period is as follows:
TC(k+1)＝max(min(T′C(k+1),Tmax),Tmin)
in the formula, TC(k +1) represents a signal period value of the (k +1) th signal optimization interval;
optimizing an identification bit for the kth signal when the operating condition grade of the ith phase is smooth, wherein the value is 1 if the operating condition grade of the kth phase is smooth, and the value is 0 if the operating condition grade of the kth phase is smooth; t isΔA step value adjusted once for each phase;
optimizing an identification bit for the kth signal at an interval with the ith phase operating condition grade being congestion, wherein if the operation condition grade is congestion, the value is 1, and if not, the operation condition grade is 0; i represents the number of phases; eta indicates that the operating conditions of the phases are all slow and
if so, the value is 1, otherwise, the value is 0; beta represents the control expectation of the user on the operation index, and max (,) represents a function of taking the maximum value of the two; min (,) represents taking the minimum function of both; t ismaxAnd TminRespectively representing the maximum value and the minimum value of the signal period allowed to be adopted by the intersection; the early peak period refers to that the working hours specified by the local people government are delayed by one hour before and one hour after each working hour; the late peak period refers to that the off-duty time specified by the local people government is delayed by one hour before and one hour after work; tti (k) represents the traffic running index average for all phases of the current signal optimization interval; TTI (k-1) represents the traffic running index average of all phases of the last signal optimization interval;
[2] during off-peak periods, the formula for periodic updates is as follows:
TC(k+1)＝max(min(TC″(k+1),Tmax),Tmin)
in the formula (I), the compound is shown in the specification,
an identification bit with the kth signal optimization interval and the ith phase operation condition grade being slow is provided, if the identification bit is slow, the identification bit is 1, otherwise, the identification bit is 0;
all the operation condition grades of all the phases are smooth and meet
If so, it is 1, otherwise, it is 0.
2. The internet data-oriented intersection signal dynamic optimization method according to claim 1, wherein in step S2, the processing of the acquired internet data into a data format required for signal optimization specifically includes the following steps:
firstly, defining a signal optimization interval as a time interval of a dynamic optimization primary signal timing scheme, excluding phase and phase sequence design, and recording as T1And is an integer multiple of the period; calculating and storing the average travel speed in the current signal optimization interval on the basis of the signal optimization interval;
secondly, carrying out data preprocessing, including data restoration and smoothing, on the average travel speed of the current signal optimization interval;
finally, defining the grade of traffic running conditions according to the processed average travel speed of each inlet direction and steering type of the intersection, and dividing the grade into three grades of smoothness, slowness and congestion;
the basic principle of the grade division of the traffic running condition is as follows:
[1]when v (k) is not less than 0.67vfMeanwhile, the grade of the traffic running condition is smooth and is marked as 0; wherein v (k) represents the mean travel speed acquired at the k-th signal optimization interval, if no data is acquired
Instead of this, the user can,
a predicted average travel speed representative of a current k-th signal optimization interval; v. offRepresenting the traffic flow travel speed in a free flow state on a road section;
[2]when 0.33vf≤v(k)＜0.67vfMeanwhile, the grade of the traffic running condition is slow and is marked as 1;
[3]when v (k) < 0.33vfIn time, the grade of the traffic running condition is congestion and is marked as 2;
meanwhile, a traffic operation index, which is defined as a ratio of the free flow speed to the actual average travel speed, is calculated.
3. The internet-data-oriented intersection signal dynamic optimization method of claim 2, wherein when no data is collected in the current signal optimization interval, the data restoration is to perform smoothing processing by using historical data, and the average travel speed meter algorithm method of the restored current signal optimization interval is as follows:
in the formula (I), the compound is shown in the specification,
a predicted average travel speed representative of a current k-th signal optimization interval; v (k-1) is the average travel speed actually acquired in the k-1 signal optimization interval;
representing the predicted value of the average travel speed in the optimization interval of the k-1 signal; alpha represents a smoothing coefficient, and parameter calibration is performed by a least square method.
4. The method for dynamically optimizing intersection signals based on internet data as claimed in claim 2, wherein the smoothing process is to replace the average speed of travel of the current signal optimization interval with the maximum free flow speed when the average speed of travel of the current signal optimization interval exceeds the actual possible speed range.
5. The method for dynamically optimizing intersection signals based on internet data as claimed in claim 1, wherein in step S3, if the following rule is satisfied, the signal optimization is required to be started:
[1]current time of day
When the current is over;
[2] when the levels of the traffic running conditions corresponding to the phases are not completely the same;
[3]when in use
When the current is over;
in the formula, T1Defining a time interval for dynamically optimizing a primary signal timing scheme for a signal optimization interval, wherein the time interval does not comprise phase and phase sequence design; n is an integer; mod (nT)1,TC) A remainder part representing a numerical value obtained by dividing the first term by the second term in parentheses; t isCRepresenting the signal period adopted by the intersection at the current moment; tti (k) represents the traffic running index average for all phases of the current signal optimization interval; beta represents the control expectation of the user on the operation index.
6. The method for dynamically optimizing intersection signals for internet data according to claim 5, wherein β is less than or equal to 0.2.
7. The method for dynamically optimizing intersection signals for internet data according to claim 1, wherein the green time of the last phase I is corrected by the following formula:
in the formula, TC(k +1) represents the signal period value of the (k +1) th signal optimization interval,
represents the green time of the (k +1) th signal optimization interval and the ith phase,
represents the (k +1) th signal optimization interval, the green time of the (I) th phase, I represents the number of phases,
representing the yellow light time of the (k +1) th signal optimization interval and the ith phase, and taking the same phase and not less than 3 s;
indicating the k +1 signal optimization interval, the full red time of the ith phase.
8. The method for dynamically optimizing intersection signals based on internet data as claimed in claim 1, wherein in step S1, the basic principles of signal timing include the following:
(1) the premise of the design of the left-turn special phase is that a special left-turn lane is provided and any one of the following conditions is met;
a) when the left-turn single lane flow is 100-;
b) when the left-turn single lane flow exceeds 200 pcu/h;
c) traffic accidents occur 5 times or more per year in three years on average, and accident cause analysis can avoid the accident intersections by setting a special left-turn phase;
d) the death traffic accidents occur 1 time or more per year in three years on average, and the accident cause analysis can avoid the intersection where the accident occurs by setting a special left-turn phase;
(2) the premise of adopting single import release is that any one of the following conditions is met:
a) the difference of the flow of the single lane for straight and left turn in the opposite direction is not less than 100-200 pcu/h; and the difference of the flow of the single lane for straight and left turn in the same direction is not more than 100-200 pcu/h;
b) for intersections without a left-turn special lane, traffic accidents occur 5 times or more per year in three years on average, and the accident reason analysis can avoid the intersections with the accidents by setting a single-inlet release phase; or the death traffic accidents occur 1 time or more per year in three years on average, and the accident reason analysis can avoid the intersection where the accidents occur by setting a single-inlet release phase;
(3) the principle of setting the upper and lower limits of the period refers to the following requirements:
a) the maximum period consideration factors comprise the psychological bearing capacity of a driver and the distance between the upstream road section and the downstream road section, so that the road section overflow caused by overlarge period is prevented;
b) the minimum period needs to meet the safe crossing time of the pedestrians in all directions;
for intersections without detectors, the internet cannot provide the traffic flow involved in the process, and the traffic flow is obtained through manual investigation and used as historical experience information to design the phase and the phase sequence.
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