CN105679032A - Traffic control subsegment division method in city traffic flow oversaturation state - Google Patents

Abstract

The invention relates to a traffic control subsegment division method in a city traffic flow oversaturation state, which is provided specific to the characteristics of traffic flow in large scale city road network oversaturation state, and realizes subsegment division on intersections of similar passage states in a road network based on a city traffic congestion formation mechanism. According to the constantly changing traffic flow in an oversaturation state, the method performs dynamic division, and provides reliable basic conditions for the realization of a signal control algorithm in an oversaturation state; according to the real time detection data of each intersection and section in the road network, the method can automatically identify intersection and section congestion states, and dynamically divide oversaturation subsegments according to the intersection and section congestion states. The method can effectively perform subsegment division on a city oversaturation road network, has the automatic and real-time dynamic oversaturation subsegment division effect which is better than traditional single oversaturation subsegment division, and provides an effective division method for the road network in a city oversaturation state.

Description

A kind of traffic control sub-area division method under urban traffic flow hypersaturated state

Technical field

The present invention relates to wisdom field of traffic, particularly relate to a kind of traffic control sub-area division method under urban traffic flow hypersaturated state.

Background technology

Along with the development of urban economy, vehicle guaranteeding organic quantity presents the state of increase fast, and urban road increases limited and slow, the normal traffic trip in city is caused seriously to be obstructed, traffic congestion takes place frequently, vehicle transport efficiency significantly declines, and affects the normal trip of city resident, governs economic development. Special in big city, supersaturation traffic congestion has become normality. Supersaturation traffic congestion and the following problem such as environmental pollution and energy shortage have become the great problem affecting urban development and civil plantation level.

As extremely important means of Modern City Traffic management, whether the quality of Controlling Traffic Signals in Urban Roads design optimization will decide dredging that urban road vehicle runs to a great extent. But the traffic efficiency of vehicle under supersaturation traffic behavior is extremely low, energy consumption is very big. Therefore designing the control of the signal under city supersaturation traffic behavior is the emphasis administering Urban traffic.

Complicated city road network is under supersaturation traffic behavior, in road network administrative area, different zones has different traffic characteristic (comprising trafficm ode structure, the volume of traffic, the flow direction etc.), it carries out total tune is very difficult, because general road network cooperation control needs the unified signal period, and make time signal period of crossings all in city equal or become multiple relation to be unrealistic. It is thus desirable to span of control is divided into different control areas, corresponding control program is designed according to the traffic flow feature of self in each control area, namely needs to divide control work zone under hypersaturated state.

As the prerequisite of supersaturation traffic behavior signal coordinated control, under supersaturation traffic behavior, the division methods in subarea has following feature: if 1. having similar traffic character between adjacent crossing, they then should be divided in same control work zone, continuous to guarantee that traffic flow runs.2. need to judge to be divided into adjacent crossing the evacuation whether same control work zone contributes to supersaturation stream; 3. need to consider to join in supersaturation control work zone by crossing lower for some saturation ratios, to allow saturated wagon flow obtain the continuous release of fast and stable, alleviate supersaturation traffic behavior.

1) supersaturation traffic behavior sub-area division method has achievement in research both at home and abroad, SCATS system carries out adaptive control using subsystem (sub-system) form as minimum coordination unit, the concept in its subsystem and subarea, when traffic flow changes time, its subarea is readjusted by each crossing traffic situation and their dependencys each other. and two is defining of control texture scope claimed according to supersaturation control strategy. and Tongji University's poplar twilight is from differentiation supersaturation section, taking the relational degree between crossing as quantizating index, set up and validate association degree computation model, and by defining blocked-off region, zone of transition and normality district and dissipation district propose the method for dynamically partitioning of traffic control community under hypersaturated state. but the hypersaturated state identification at crossing is not considered in above-mentioned research in time, and block up and spread to face again to line by point, therefore can affect the effect of division.

Summary of the invention

The present invention overcomes above-mentioned weak point, object is to provide a kind of traffic control sub-area division method under urban traffic flow hypersaturated state, present method is according to the real-time detector data at crossing each in road network and section, automatically identify crossing and section jam level, more dynamically divide supersaturation subarea with the jam level in crossing, section; Can promptly and accurately identify supersaturation crossing in time and dynamically divide subarea, be conducive to improving signal controlling efficiency under supersaturation traffic behavior.

The present invention achieves the above object by the following technical programs: a kind of traffic control sub-area division method under urban traffic flow hypersaturated state, comprises step as follows:

(1) calculate according to the real-time detector data in crossing and section in each phase place of single intersection and flow mostly to saturation ratio, queuing ratio that each phase place flows mostly to section, upstream;

(2) the queuing ratio utilizing each phase place to flow mostly to section, upstream calculates section congestion degree;

(3) judge that each phase place of single intersection flows mostly to saturation ratio, queue up in section, upstream and than whether all reach respective threshold value, if all reaching threshold value, then using this crossing as sub-area division starting point; Otherwise terminate; Wherein threshold value is default;

(4) judge to be connected with sub-area division starting point crossing the real-time section congestion degree in section, if real-time section congestion degree reaches threshold value, then joins in this subarea by the crossing that section and two ends thereof are connected, performs next step after taking out the crossing newly adding subarea; If without the connected section reaching threshold value, sub-area division terminates, and this crossing is divided into separately a subarea; Wherein threshold value is default;

(5) the starting point single or multiple crossings newly adding subarea extended as subarea successively, extract the real-time section congestion degree in the section that is connected with crossing, if the real-time congestion degree in section exceedes threshold value, then this section and connected crossing thereof are joined in subarea, take out the crossing newly adding subarea, enter step (6); If without reaching threshold value section, then terminating the diffusion in subarea, sub-area division terminates; Wherein threshold value is default;

(6) repeated execution of steps (5), until sub-area division terminates.

As preferably, the formula flowing mostly to saturation ratio in each phase place of described step (1) calculating single intersection is as follows:

$x_{i,j}=\frac{q_{i,j}}{C_i}=\frac{q_{i,j}}{{\mathrm{\λ}}_i{q}_{s,i}}$

Wherein, q_i,jFor the traffic flow flowing mostly to j arrival stop line of phase place i, unit is veh/h;C_iFor the traffic capacity of phase place i, unit is PCU/h; λ_iFor the green letter of phase place i compares; q_s,iFor the saturated flow of phase place i, unit is PCU/h.

As preferably, in described step (1), the calculation formula of the queuing ratio that each phase place flows mostly to section, upstream is as follows:

$l=\frac{L}{L_R}$

Wherein, L be phase place flow mostly to section, upstream after phase place green light terminates queuing length, L_RFor the length in section.

As preferably, definition and the calculation formula of described step (2) section congestion degree are as follows:

C=max (l₁, l₂)

$l_1=\frac{L_1}{L_{R1}}$

$l_2=\frac{L_2}{L_{R2}}$

Wherein, C is the section between two adjacent crossings, l₁、l₂For the section R that Liang Ge direction, this section is corresponding₁、R₂Queuing ratio.

The useful effect of the present invention is: (1) present method can identify supersaturation crossing timely and accurately and dynamically divide subarea, is conducive to improving signal controlling efficiency under supersaturation traffic behavior; (2) supersaturation road network in city being carried out effective sub-area division, multi-class supersaturation sub-area division effect is better than the single supersaturation sub-area division of tradition.

Accompanying drawing explanation

Fig. 1 is the city road network schematic diagram in the embodiment of the present invention.

Embodiment

Below in conjunction with specific embodiment, the present invention is described further, but protection scope of the present invention is not limited in this:

Embodiment: as shown in Figure 1, one has the city road network at 12 crossings, and there is care testing device in each crossing and section for detecting the volume of traffic needed for each: the green letter ratio of the flow direction that crossing respectively flows to, the length of the queuing of vehicle, crossing signal. Having the flow direction (also likely only having a flow direction) that two main between any two crossings, be designated as a section, there is a real-time crowding in every bar section. First assume that in these 12 crossings, multiple crossing reaches the traffic behavior of supersaturation, concrete determination methods following 1) shown in, A crossing is one of them, wherein the crowding in the section that AB, BC, AD, DE, EF represent exceedes threshold value, and in road network, other section crowdings all do not exceed threshold value. Following step is assumed first from the A of crossing, divide subarea.

A kind of traffic control sub-area division method under urban traffic flow hypersaturated state: according to real-time traffic, the queuing ratio flowing mostly to saturation ratio, connected section of dynamic calculation crossing phase place, all cross the calculating to this two indices, identify the crossing of the state of reaching capacity, and then the crowding of combining road carries out the division in subarea, step is as follows:

1) by define and calculate flow to saturation ratio, section queuing than the supersaturation traffic behavior identifying single intersection:

First calculate in each phase place of single intersection and flow mostly to saturation ratio:

$x_{i,j}=\frac{q_{i,j}}{C_i}=\frac{q_{i,j}}{{\mathrm{\λ}}_i{q}_{s,i}}$

In formula: q_i,jFor the traffic flow (veh/h) flowing mostly to j arrival stop line of phase place i, C_iFor the traffic capacity (PCU/h) of phase place i, λ_iFor the green letter ratio of phase place i, q_s,iFor the saturated flow (PCU/h) of phase place i;

Then the queuing ratio that each phase place flows mostly to section, upstream is calculated:

$l=\frac{L}{L_R}$

In formula: L be phase place flow mostly to section, upstream after phase place green light terminates queuing length, L_RFor the length in section.

Can judge: work as x_i,jTime bigger, it is possible to think that the wagon flow amount of this flow direction is bigger. Work as x_i,jWhen being greater than a threshold value, it is possible to think the state of reaching capacity. Work as x_i,jTime less, then two kinds of situations may occur, one is that wagon flow amount is natively smaller, and two is because the traffic behavior that crossing reaches supersaturation causes lower wagon flow dissipation degree, it is thus desirable to the queuing situation by vehicle is in addition dialectical, namely works as x_i,jWhen being less than certain threshold value, such as x_i,j<0.3, then also to be got the queuing flowing mostly to the corresponding section, upstream of j than l, if queuing up than being greater than certain threshold value, such as l>0.1, then can judge that this flow direction has been in hypersaturated state.

2) definition and calculating section crowding:

C=max (l₁,l₂)

$l_1=\frac{L_1}{L_{R1}}$

$l_2=\frac{L_2}{L_{R2}}$

In formula: C is the section between two adjacent crossings, l₁、l₂For the section R that Liang Ge direction, this section is corresponding₁、R₂Queuing ratio.

3) sub-area division is carried out:

Step1: the isolated intersection traffic state identification method in 2 carries out traffic status identification in all crossings in road network to specifying as requested, puts into a set M by all crossings reaching hypersaturated state_kIn. Make i=j=k=0;

Step2: at set M_kIn choose any one crossing and (m might as well be designated as_k) as the division starting point in single subarea;

Step3: by m_kA set A is put at crossing_i, note a_i,sFor A_iIn the s crossing element;

Step4: get crossing a_i,sThe congested in traffic degree l in connected section, judges the crowding threshold value l whether each section crowding is definite more than successively_omax, by l > and l_omaxSet B is put at the crossing that section is connected;

Step5: judge whether A_iIn all crossings all processed through Step4, if not, enter Step6, if yes then enter Step7;

Step6: make s=s+1, returns Step4;

Step7: judge whether i > 0, if, then order set C=B-A_i∪A_i-1, if not, make C=B-A_i;

Step8: judge whether set C is empty, if not empty, then carries out next step. If it is empty, then Step10 is entered;

Step9: make i=i+1, puts into set A by crossing in set C_i, clear empty set B, C, make s=0 return to Step4;

Step10: make T_j=A₀∪A₁∪...A_i, k=k+1, j=j+1, make M_k=M_k-1-M_k-1∩T_j-1;

Step11: judge M_kWhether it is empty, then returns to Step2 if not empty. Then carry out next step if it is empty;

Step12: divide end and obtain subarea: T₁,T₂...T_j。

By above method, the subarea that contains ABCDEF crossing finally can be obtained.

The know-why being specific embodiments of the invention and using described in above, if the change done according to the conception of the present invention, its function produced does not exceed specification sheets yet and accompanying drawing is contained spiritual time, protection scope of the present invention must be belonged to.

Claims (4)

1. the traffic control sub-area division method under a urban traffic flow hypersaturated state, it is characterised in that, comprise step as follows:

(1) calculate according to the real-time detector data in crossing and section in each phase place of single intersection and flow mostly to saturation ratio, queuing ratio that each phase place flows mostly to section, upstream;

(2) the queuing ratio utilizing each phase place to flow mostly to section, upstream calculates section congestion degree;

(3) judge that each phase place of single intersection flows mostly to saturation ratio, queue up in section, upstream and than whether all reach respective threshold value, if all reaching threshold value, then using this crossing as sub-area division starting point; Otherwise terminate; Wherein threshold value is default;

(4) judge to be connected with sub-area division starting point crossing the real-time section congestion degree in section, if real-time section congestion degree reaches threshold value, then joins in this subarea by the crossing that section and two ends thereof are connected, performs next step after taking out the crossing newly adding subarea; If without the connected section reaching threshold value, sub-area division terminates, and this crossing is divided into separately a subarea; Wherein threshold value is default;

(5) the starting point single or multiple crossings newly adding subarea extended as subarea successively, extract the real-time section congestion degree in the section that is connected with crossing, if the real-time congestion degree in section exceedes threshold value, then this section and connected crossing thereof are joined in subarea, take out the crossing newly adding subarea, enter step (6); If without reaching threshold value section, then terminating the diffusion in subarea, sub-area division terminates; Wherein threshold value is default;

(6) repeated execution of steps (5), until sub-area division terminates.

2. the traffic control sub-area division method under a kind of urban traffic flow hypersaturated state according to claim 1, it is characterised in that: the formula flowing mostly to saturation ratio in each phase place of described step (1) calculating single intersection is as follows:

$x_{i,j}=\frac{q_{i,j}}{C_i}=\frac{q_{i,j}}{{\mathrm{\&lambda;}}_i{q}_{s,i}}$

Wherein, q_i,jFor the traffic flow flowing mostly to j arrival stop line of phase place i, unit is veh/h; C_iFor the traffic capacity of phase place i, unit is PCU/h; λ_iFor the green letter of phase place i compares; q_s,iFor the saturated flow of phase place i, unit is PCU/h.

3. the traffic control sub-area division method under a kind of urban traffic flow hypersaturated state according to claim 1, it is characterised in that: in described step (1), the calculation formula of the queuing ratio that each phase place flows mostly to section, upstream is as follows:

$l=\frac{L}{L_R}$

Wherein, L be phase place flow mostly to section, upstream after phase place green light terminates queuing length, L_RFor the length in section.

4. the traffic control sub-area division method under a kind of urban traffic flow hypersaturated state according to claim 1, it is characterised in that: definition and the calculation formula of described step (2) section congestion degree are as follows:

C=max (l₁, l₂)

$l_1=\frac{L_1}{L_{R1}}$

$l_2=\frac{L_2}{L_{R2}}$

Wherein, C is the section between two adjacent crossings, l₁、l₂For the section R that Liang Ge direction, this section is corresponding₁、R₂Queuing ratio.