CN101246514A - City fast road intercommunicated overpass simulation design system and method for establishing design model - Google Patents

Abstract

The invention discloses a simulating design system for city expressway interchanges, comprising: data acquisition, model calibration, a data-out module, an evaluation and analysis module connecting with the model calibration module and data-out module respectively, and a data amendment module connecting between the evaluation and analysis module and the model calibration module. Meanwhile a model building and design method using the design system is disclosed too, which comprises: collecting the characteristic parameter of the traffic flow of typical expressway basic sections, interchange triage/confluence area, cutting area and various ramps; building the corresponding database and traffic capacity theoretical analysis model; demarcating and amending a speed and density model with determinate service level; building a traffic capacity analysis model suiting the traffic flow characteristic of the city expressway interchanges. Designers can carry out the adaptability analysis of the interchanges for communications using the design model, so as to conduct the design of the lectotype of the city expressway interchanges.

Description

The method that city expressway interchange simulation design system and foundation design a model

Technical field

The present invention relates to a kind of city expressway interchange planning and design system, especially relate to a kind of simulation design system that is used for the city expressway interchange.

Background technology

City expressway (urban expressway) is built for satisfying high capacity in the city, long distance, rapid transit, dividing strip, the roadnet that adopts totally-enclosed, full-overpass, all or part of control to come in and go out continuously in the middle of being provided with.The through street provides each interregional function of carrying out quick, safe, comfortable traffic trip in the city for vehicle.And hinge type interchange is the important transport node in the system of through street, is the key that maximum function be brought into play in the decision through street can.Therefore whether most important the scientific rationality of the scale of hinge type interchange and form is.

At present, since socioeconomic fast development, the city extension, population and land scale constantly enlarge, and trans-regional in the city, branch is formed a team, passenger-cargo traffic of long distance increases considerably, and has increased the traffic pressure of present situation road network.For the contradiction between the transport need of alleviating sharp increase and the limited road traffic facility.Though build in a large number in the whole nation through street in recent years, to the through street systematic research, particularly the research of the traffic stream characteristics of through street hinge interchange and the traffic capacity still belongs to blank.The city develops rapidly, causes the urban transportation demand rapidly to increase, and causes imbalance between supply and demand to strengthen.Especially during morning, evening peak, traffic congestion often occurs in gateway, interchange district and interwoven region, makes the interchange district become " traffic bottlenecks " location of through street system.For this reason, must carry out research to the through street interchange traffic capacity, planning, design and traffic administration with the scientific guidance city expressway, simultaneously, planning, design and traffic administration to each city traffic network will be played crucial exemplary role, and this research will remedy the blank of China in this field.

Current, the subject matter that exists at the through street interchange have following some:

1) interchange whole traffic stream characteristics in through street was not carried out systematic study as yet.Up to now, the grade separation part under the unsaturation transportation condition is paid close attention in most of research, as branch/interflow district, acceleration and deceleration track etc.These local achievements in research can not solve the problem of blocking up that whole interchange occurs under the saturated traffic behavior.Rapid growth along with the urban transportation amount, each big city, such as: the through street, Tianjin the highway section (daily traffic volume in 2007: 44738 in North-south direction, the south-north have increased nearly 25% to 41000 than 2006) of big flow just occurred in the short year that is open to traffic.After the prediction operation for many years, the volume of traffic can be tending towards state of saturation gradually on the through street, and therefore the whole traffic stream characteristics research to the city expressway interchange under the state of saturation is very necessary.

2) design phase of interchange lacks scientific basis to the computing method of the traffic capacity, and the adaptability of interchange distant view prognosis traffic volume is not still had the science assessment method.At present, calculate the interchange traffic capacity owing in the design of through street, adopt the method for " traffic capacity in all directions import track multiply by certain coefficient " usually, and branch/interflow district and weaving section capacity are not checked, often cause calculating inaccurate consequence.And if result of calculation is excessive, the scale of grade separation and cost will significantly improve, and not only take urban land, and cause the increase of construction cost and the idle waste of infrastructure; If result of calculation is low excessively, then can not satisfy the demand of volume of traffic development, reduced the adaptive faculty that the volume of traffic is changed simultaneously, do not match with road section capacity, become the traffic bottlenecks on the through street, influence urban transportation.

Determining of the scale of city expressway interchange and form should be according to the reasonable prediction value of the volume of traffic at a specified future date.The volume of traffic at a specified future date is in the traffic forecast of urban development after the regular period.The city constantly changes development, causes the road network of interchange periphery and transport need also in continuous variation, so interchange turns to the ratio of traffic also to change thereupon.Do the design scale of interchange and form have much to the adaptedness of the volume of traffic of long-range forecasting? should take what scheme and measure during incompatibility? these problems all need research.In addition, at present still none is fit to analyze strong instrument of the through street interchange traffic capacity in the analysis software of lot of domestic and foreign, therefore explores a cover city expressway interchange Traffic Capacity Analysis by research and forecasting software also is general demand.

In sum, improve the computing method of the interchange traffic capacity, rationally determine the scale and the form of interchange, to the adaptability that improves interchange, save urban land, reduce traffic noise, improve urban environment etc. and all have crucial meaning.

3) domestic through street and urban road cross-over design rules are worked out, and the design of through street interchange lacks standard and instructs.It is not long that China builds time of through street, the planning of through street and ingredient-interchange thereof and design, still be in a large number at present put into practice, experience accumulation and theoretical research stage.Through street and urban road cross-over design rules establishment speed are slow, and in the design of through street interchange, the designer is mostly with reference to data at home and abroad and other technical standards such as " specification of the highway route design ", " urban road design specificationss ".In use find some indexs of domestic standard and be not suitable for through street interchange design, mainly show: " specification of the highway route design " index is too high, and the city expressway interchange is because the urban land restriction can not reach its requirement; Indexs of correlation such as " urban road design specificationss " is corresponding again low excessively, and the through street interchange will satisfy the high speed branch of vehicle/collaborate and interweave, and is obviously improper with reference to above codes and standards.And do not provide interchange Traffic Capacity Analysis computing method and service level index system in the standard, external reference does not meet China's specific national conditions again, therefore how to improve interchange Traffic Capacity Analysis computing method and service level index system, instruct the planning and design of through street to become the task of top priority.

Summary of the invention

In order to solve the problems of the technologies described above conscientiously, the invention provides the method that a kind of city expressway interchange simulation design system and foundation design a model, utilize this design system and design a model the traffic capacity problem of city expressway interchange is studied, emergency measure with evaluation analysis interchange reply traffic congestion, improve interchange traffic capacity computing method, replenish and improve the city expressway design discipline, it is more objective to be used for, scientifically instruct the planning and the design of city expressway, improve the city expressway interchange traffic capacity, improve city expressway interchange design level, fill up the blank of China's city expressway interchange traffic capacity research.And solve simultaneously that existing some technical matters provides following some scientific basis in the above-mentioned prior art:

1) proposes the traffic capacity of interchange, determine to provide scientific and rational foundation for the type selecting of newly-built through street interchange and linear index;

2) propose the capacity and level-of-service analytical standard, be used for estimating newly-built and built interchange traffic flow running quality, assess roading, design and Managed Solution;

3) set up interchange emulation planning and designing method.By the emulation experiment platform, predict respectively that in future the ruuning situation under the annual traffic situation predicts to planning to build, built interchange, in time find the problem in planning, the design, become the new method of grade separation planning and design;

4) research of the through street interchange traffic capacity will provide the basic data of science for revising related city through street design standards and rules.

In order to solve the problems of the technologies described above, city expressway interchange simulation design system of the present invention be achieved ground technical scheme be: comprise data acquisition module, model calibration module and data outputting module, also comprise the evaluation analysis module that connects with model calibration module and data outputting module respectively, between evaluation analysis module and model calibration module, also be connected with the data correction module; The described Traffic Flow Simulation Models module of setting up comprises traffic characteristics theoretical model and traffic simulation software.

A kind of method of setting up city expressway interchange simulation design system model among the present invention may further comprise the steps:

(A) utilize the interior traffic characteristics flow data of highway section, branch/interflow district, interwoven region and ring road substantially in data collecting module collected interchange typical case district:

(B) draw the traffic stream characteristics data of actual traffic situation according to the above-mentioned data that collect;

(C) according to above-mentioned data scaling empirical model and the realistic model that collects, and set up forecast model, comprising:

(C-1) utilize the traffic stream characteristics theoretical model that the above-mentioned data that collect are carried out theoretical analysis;

Basic capacity to basic highway section, shunting zone, interflow district and interwoven region carries out theoretical analysis: according to becoming to follow the saturation headway between the two cars of front and back in the fleet of relaxation state mutually on two tracks in the shunting zone that collects, application of formula (1-1) is carried out the calculating of shunting zone and interflow district basic capacity respectively:

$C=\frac{3600}{\stackrel{\‾}{t}}---(1-1)$

In the formula (1-1): C---the branch/interflow district traffic capacity, pcu/h.,

---average minimum time headway, s;

The basic traffic ability of interwoven region: C _i=3600 λ _ImaxM _i(1-2)

$C=\underset{i}{\mathrm{\Σ}}{C}_i---(1-3)$

In formula (1-2) and the formula (1-3):

C---the total traffic capacity of interwoven region;

C _i---the traffic capacity in i track;

λ _Imax---the desirable maximum in the i track rate of sending a car, by formula ${\mathrm{\λ}}_{1\·\max }=\min \{{\widetilde{\mathrm{\λ}}}_{1\max },C_0\}$ And formula ${\mathrm{\λ}}_{2\·\max }=\min \{{\widetilde{\mathrm{\λ}}}_{2\max },C_0\}$ Determine, wherein: C ₀---the basic capacity in every track;

m _i---the possibility size that effective neutral in i track is utilized, determine by formula (1-4) and formula (1-5),

$m_1=1-\frac{Q_1\·r_1-{\tilde{Q}}^2}{Q_1\·r_1}---(1-5)$

(C-2) demarcate empirical model and realistic model respectively according to the above-mentioned data that collect, comprising:

(1) according to the above-mentioned data that collect empirical model is demarcated and is revised, thereby set up following each regional forecast model:

Interchange shunting zone Forecasting Model of Density:

K _R＝0.484+0.00013Q _R+0.011Q ₁₂-0.0183L _D (2-1)

Interchange shunting zone speed prediction model:

V _R＝V _FF-(V _FF-50)(1.15+0.0002Q _R-0.008V _FR) (2-2)

Interchange interflow district Forecasting Model of Density:

K _R＝1.1+0.0059Q _R+0.0074Q ₁₂-0.01278L _A (2-3)

Interchange interflow district speed prediction model:

$V_R=V_{\mathrm{FF}}-(V_{\mathrm{FF}}-50)(0.78+0.01e^{(Q_{R12}/1000)}-0.004(L_A{V}_{\mathrm{FR}}/1000)---(2-4)$

The interchange interwoven region speed prediction model that interweaves:

$V_w=24+\frac{V_{\mathrm{FF}}-16}{1+\frac{0.0192{(1+Q_R)}^{7.21}{\left(\frac{Q}{N}\right)}^{1.133}}{{\left(3.28L\right)}^{0.8}}}---(2-5)$

The non-speed prediction model that interweaves of interchange interwoven region:

$V_w=24+\frac{V_{\mathrm{FF}}-16}{1+\frac{0.0178{(1+Q_R)}^{4.19}{\left(\frac{Q}{N}\right)}^{0.997}}{{\left(3.28L\right)}^{0.75}}}---(2-6)$

(2) carry out the demarcation of Traffic Flow Simulation Models according to the above-mentioned data that collect;

(D) utilize the evaluation analysis module to judge that respectively the Traffic Flow Simulation Models of above-mentioned forecast model and demarcation compares with the traffic stream characteristics of actual traffic situation, its both error is≤10%; If judged result is returned falsity, then return above-mentioned steps (C-2), demarcate empirical model and realistic model again; If judged result is returned true value, order is carried out next step;

(E) determine capacity and level-of-service according to The above results, and export following index: the traffic capacity of determining basic highway section, shunting zone, interflow district, interwoven region and all types of ring roads by data outputting module.

Compared with prior art, the beneficial effect that the present invention had is:

(1) because the simulation design system that the present invention is used for the city expressway interchange is on the basis of all interchange forms of investigation through street, Tianjin comprehensively, be the systematic study targetedly that object launches with typical grade separation form.Finally set up Traffic Flow Simulation platform based on actual measurement driving behavior data; Explored the test method of interchange Traffic Capacity Analysis; Quantized the traffic capacity of different interchange schemes; Recommended value in city expressway interchange design objective reasonable value scope has been proposed.

(2) design system of the present invention not only can improve the design level of city expressway interchange, support for planning, design and the traffic administration of a large amount of communication projects yet to be built in the large-and-medium size cities provides valuable experience and reliable technique, and provide the basic data of science for improving city expressway design standards, city expressway design discipline and urban road intersection design discipline.

(3) utilize the simulation design system of city expressway interchange of the present invention, the designer can carry out the Adaptability Analysis of interchange to transportation conditions such as the volume of traffic of continuous variation, driving behavior, vehicle compositions.The present invention is abundant and developed current grade separation method for designing and evaluation means.

Description of drawings

Fig. 1 is the structured flowchart that the present invention is used for the simulation design system of city expressway interchange;

Fig. 2 utilizes design system shown in Figure 1 to set up the main flow chart of realistic model;

Fig. 3 utilizes the theorize interwoven region pictorial image of model of design system shown in Figure 1;

Fig. 4 utilizes realistic model shown in Figure 2 to carry out the flow process of grade separation Selection and Design;

Fig. 5 is the crossing traffic discharge diagram of Selection and Design embodiment;

Fig. 6-1, Fig. 6-2 and Fig. 6-the 3rd, three kinds of type selecting synoptic diagram of the interchange at crossing shown in Figure 4;

Fig. 7 is a crossing shown in Figure 5 grade separation traffic flow map.

Embodiment

Below in conjunction with the drawings and specific embodiments the present invention is described in further detail.

As shown in Figure 1, city expressway interchange simulation design system of the present invention, comprise data acquisition module, model calibration module, evaluation analysis module and data outputting module, the evaluation analysis module that described data acquisition module also links and connects with model calibration module and data outputting module respectively also comprising with the evaluation analysis module also is connected with the data correction module between evaluation analysis module and model calibration module; Described model calibration module comprises traffic stream characteristics theoretical model and traffic simulation software; Described traffic stream characteristics theoretical model adopts and can intert gap theory and service level theory, and described Traffic Flow Simulation Models adopts VISSIM software.Described data acquisition module comprises vehicle magnetic reflection traffic analysis, vehicle somatotype statistical system, GPS, video camera and computing machine; Described vehicle magnetic reflection traffic analysis adopts NC-97 type vehicle magnetic reflection traffic analysis, and described vehicle somatotype statistical system adopts MetroCount vehicle somatotype statistical system.

Utilizing above-mentioned city expressway simulation design system to set up the method that designs a model may further comprise the steps:

(A) utilize the interior relevant data of highway section, branch/interflow district, interwoven region and ring road substantially in above-mentioned data collecting module collected interchange typical case district.

Comprise following data:

---the magnitude of traffic flow, the speed of a motor vehicle, length over ends of body, time headway and density;

---axletree is through speed, flow, time headway, wheelbase and the number of axle in the moment of sensor;

---locating information, travel speed, time and the driving trace of vehicle;

---road conditions, Turning movement, traffic composition and main line and ring road interleaving process, the vehicle position of changing trains;

---changes in vehicle speed characteristic on the interior various ring roads of acceleration-deceleration characteristic and typical case district of typical vehicle;

---utilize the data of data processor intercepting random time section in the GPS, behind the rejecting invalid data, generate coordinate and time data; Make the CAD figure of vehicle driving trace according to this coordinate and time data;

(B) draw the traffic stream characteristics data of actual traffic situation according to the above-mentioned data that collect.

Described traffic characteristics data comprise such as the speed of a motor vehicle, flow, time headway and density etc.;

(C), and set up forecast model according to above-mentioned data scaling realistic model that collects (for example this realistic model adopts the VISSIM model) and empirical model, wherein:

(C-1) utilize the traffic stream characteristics theoretical model that the above-mentioned data that collect are carried out theoretical analysis.

This traffic stream characteristics theoretical model can adopt in the prior art ripe model, can intert gap theory and service level theory as adopting; Described theoretical analysis normally carries out theoretical analysis to the basic capacity of basic highway section, shunting zone, interflow district and interwoven region: comprise that (1) carry out the calculating of shunting zone and interflow district's basic capacity; (2) basic capacity by interwoven region draws the total traffic capacity of interwoven region; Its process is as follows:

According to becoming to follow the saturation headway between the two cars of front and back in the fleet of relaxation state mutually on two tracks in the shunting zone that collects, use the calculating that following formula (1-1) carries out shunting zone and interflow district basic capacity respectively:

$C=\frac{3600}{\stackrel{\‾}{t}}---(1-1)$

In the formula (1-1): C---the branch/interflow district traffic capacity, pcu/h.,

---average minimum time headway, s;

The basic traffic ability of interwoven region: C _i=3600 λ _ImaxM _i(1-2)

$C=\underset{i}{\mathrm{\Σ}}{C}_i---(1-3)$

In formula (1-2) and the formula (1-3):

C---the total traffic capacity of interwoven region;

C _i---the traffic capacity in i track;

λ _Imax---the desirable maximum in the i track rate of sending a car, by formula ${\mathrm{\λ}}_{1\·\max }=\min \{{\widetilde{\mathrm{\λ}}}_{1\max },C_0\}$ And formula ${\mathrm{\λ}}_{2\·\max }=\min \{{\widetilde{\mathrm{\λ}}}_{2\max },C_0\}$ Determine, wherein: C ₀---the basic capacity in every track;

m _i---the possibility size that effective neutral in i track is utilized, determine by formula (1-4) and formula (1-5),

$m_1=1-\frac{Q_1\·r_1-{\tilde{Q}}^2}{Q_1\·r_1}---(1-5)$

As follows with reference to Fig. 3 to the parameter declaration in above formula (1-4) and the formula (1-5):

Note AX track is numbering 1 track, and the BY lane number is 2 tracks;

Note Q ₁Be 1 track flow, r1 is that weaving vehicles account for Q on 1 track ₁Ratio,

Be the interweave flow rate of 1 lane flow on can receptible adjacent lane; Correspondingly, Q ₂, r ₂,

Be respectively weaving vehicles on the flow, 2 tracks in 2 tracks and account for the ratio, 2 lane flows of the Q2 flow rate that interweaves on can receptible adjacent lane.

(C-2) demarcate empirical model and realistic model respectively according to the above-mentioned data that collect, set up forecast model; Comprise:

(1) according to the above-mentioned data that collect empirical model is demarcated and revised, thereby set up following each regional forecast model;

(2) carry out the demarcation of Traffic Flow Simulation Models according to the above-mentioned data that collect.

Wherein: each regional prediction model is as follows:

Interchange shunting zone Forecasting Model of Density:

K _R＝0.484+0.00013Q _R+0.011Q ₁₂-0.0183L _D (2-1)

Interchange shunting zone speed prediction model:

V _R＝V _FF-(V _FF-50)(1.15+0.0002Q _R-0.008V _FR) (2-2)

Interchange interflow district Forecasting Model of Density:

K _R＝1.1+0.0059Q _R+0.0074Q ₁₂-0.01278L _A (2-3)

Interchange interflow district speed prediction model:

$V_R=V_{\mathrm{FF}}-(V_{\mathrm{FF}}-50)(0.78+0.01e^{(Q_{R12}/1000)}-0.004(L_A{V}_{\mathrm{FR}}/1000)---(2-4)$

The interchange interwoven region speed prediction model that interweaves:

$V_w=24+\frac{V_{\mathrm{FF}}-16}{1+\frac{0.0192{(1+Q_R)}^{7.21}{\left(\frac{Q}{N}\right)}^{1.133}}{{\left(3.28L\right)}^{0.8}}}---(2-5)$

The non-speed prediction model that interweaves of interchange interwoven region:

$V_w=24+\frac{V_{\mathrm{FF}}-16}{1+\frac{0.0178{(1+Q_R)}^{4.19}{\left(\frac{Q}{N}\right)}^{0.997}}{{\left(3.28L\right)}^{0.75}}}---(2-6)$

Above-mentioned formula (2-1) is to formula (2-6):

K _R---shunting zone and interflow district density, pcu/km/ln

Q---interwoven region total flow, pcu/h

Q _R---ring road flow, pcu/h

Q ₁₂---the main line outside two track flows, pcu/h

L---interwoven region length, m

L _A---acceleration lane length, m

L _D---deceleratuib lane length, m

V _R---shunting zone and interflow district speed, km/h

V _FF---main line free stream velocity, km/h

V _FR---ring road free stream velocity, km/h

V _W---the non-speed that interweaves, km/h

N---interwoven region number of track-lines;

(D) utilize the evaluation analysis module to judge that respectively the Traffic Flow Simulation Models of above-mentioned forecast model and demarcation compares with the traffic stream characteristics of actual traffic situation, that is: above result of calculation is verified by measured data, the difference of The model calculation and measured data all within the acceptable range, its both error should≤10%; If both errors surpass 10%, then return above-mentioned steps (C-2), demarcate empirical model and realistic model again; If both error≤10%, then above-mentioned calibrated model can be applicable to the speed and the density prediction in this city expressway interchange district;

(E) determine capacity and level-of-service according to The above results, export following index: the traffic capacity of determining basic highway section, shunting zone, interflow district, interwoven region and all types of ring roads by data outputting module.

Embodiment one:

That utilizes that design system of the present invention sets up designs a model by to traffic capacity theoretical analysis in the Tianjin interchange typical case district and demarcation and correction to realistic model, draw at basic highway section, through street, Tianjin, the traffic capacity value of interchange branch/interflow district, interwoven region, each quasi-representative ring road and interchange integral body, can be used as Tianjin interchange type selecting, the definite decision support of scheme, the traffic capacity recommendation of relevant interchange form sees Table 1 to table 5.

The basic road section capacity recommendation tables in table 1 through street

Design rate (km/h)	The bicycle road traffic capacity (pcu/h)	The section Four-Lane Road traffic capacity (pcu/h)
			80	2050	8200

The theoretical traffic capacity recommendation tables in table 2 interchange branch/zone of influence, interflow

Table 3 interchange five track weaving section capacity recommendation tables

The weaving volume ratio	0.1	0.2	0.3	0.4
					The traffic capacity (pcu/h)	9300	8200	7200	6400

The all types of ramp capacity recommendation tables of table 4

The whole traffic capacity recommendation tables of table 5 interchange

Traffic flow statistics model by each ingredient of city expressway interchange, and in conjunction with the decision method of service quality measurement index and service level, the present invention can determine basic highway section, through street, interchange branch/interflow district and the service level classification unified standard of interwoven region under standard conditions, thereby enrich, improve the act.std standard system, see Table 6 by the present invention's determined level of service division standard that designs a model.

The basic highway section of table 6, interchange branch/interflow district and interwoven region level of service division standard

In sum, utilize design system of the present invention, collected basic highway section, through street, the traffic flow character parameter of interchange branch/interflow district, interwoven region and various ring roads by to the district's observation of city expressway typical case interchange; Set up corresponding database and traffic capacity theoretical analysis model; Speed and the density empirical model of determining service level are demarcated and revised; Set up the Traffic Capacity Analysis model that is fit to this city expressway interchange traffic stream characteristics.And instruct the design of city expressway interchange type selecting with this model.

Embodiment two:

The pairing capacity and level-of-service that utilizes above-mentioned design system to draw, instruct the method for interchange type selecting may further comprise the steps:

(1) according to the present situation volume of traffic or prognosis traffic volume, to plan to build establish the district volume of traffic carry out the analysis of steering flow primary and secondary;

(2) according to the traffic capacity that obtains basic highway section, shunting zone, interflow district, interwoven region and all types of ring roads by realistic model, tentatively determine the form of interchange, this interchange form is the combination in any of one of following several forms or following several forms:

Cloverleaf, combined I and combined II;

Described combined I is the combination of semi-directional and directed ring road; Described combined II is directed ring road combination;

(3) utilize following formula to draw the grade separation traffic capacity data of above-mentioned determined interchange form:

---when the first shunt influence district of certain direction and Through Lane traffic capacity sum during less than downstream shunting zone and Through Lane traffic capacity sum or weaving section capacity, the traffic capacity of interchange i direction is first shunting zone and Through Lane traffic capacity sum, that is:

---when there is shunting zone in the downstream, if first shunting zone of this direction and Through Lane traffic capacity sum are greater than downstream second shunting zone and Through Lane traffic capacity sum, the traffic capacity of interchange i direction is the second shunting zone traffic capacity, Through Lane traffic capacity sum:

---when there was interwoven region in the downstream, if the first shunt influence district of this direction and Through Lane traffic capacity sum enter the main line traffic capacity sum of interwoven region greater than the downstream, the traffic capacity of interchange i direction was the main line traffic capacity that enters interwoven region:

C _i=C _Interweave-Δ C _{Ring road}(3-3)

---finally draw the traffic capacity of every kind of interchange form integral body respectively:

$C=\underset{i=1}{\overset{4}{\mathrm{\Σ}}}{C}_i---(3-4)$

Above-mentioned formula (3-1) to formula (3-4), C _iBe the traffic capacity of interchange i direction, unit is pcu/h; C _{Divide 1}, C _{Divide 2}, C _InterweaveBe divided into the traffic capacity of two shunting zones of i direction and interwoven region, unit is pcu/h; C _{Straight i}Be i Through Lane maximum throughput, when only there is a Through Lane in the shunting zone outside, consider distant effect, its maximum throughput is according to the second Through Lane value, and unit is pcu/h; Δ C _{Ring road}For each weaving volume than the import ring road flow under the condition, unit is pcu/h;

(4) establish district's distant view prognosis traffic volume according to planning to build, compare respectively, judge whether coupling, thereby determine that this plans to build the interchange design proposal of establishing the district with the traffic capacity of above-mentioned various interchange forms.

Described preliminary when determining the interchange form, comprise following situation:

(1) selection of ring road form: should turn to traffic to analyze to each according to prognosis traffic volume during the grade separation type selecting, and lay grade separation in conjunction with surrounding city landform and critical control point.The selection of left rotaring ring road form has determined the form of grade separation, should be according to the height of the size and the service level of ring road prognosis traffic volume, select directed ring road, semi-directional ring road and loop ramp successively for use, the plat and profile linear index of ring road should adapt with the volume of traffic simultaneously, and the ring road that the volume of traffic is big, the cart incorporation rate is high should have higher plat and profile linear index.

(2) selecting for use of interwoven region: when the grade separation type selecting, should as far as possible reduce interwoven region.During design, can change flexibly full clover blade profile grade separation according to transport need, loop ramp is the diagonal angle form be arranged in two quadrants, other quadrant should adopt directed and semi-directional ring road according to the descending order of the volume of traffic.

As limited in the time of must laying interwoven region by landform, should guarantee the interwoven region weaving volume than not being higher than 0.2.As if interwoven region and main line are adopted hard the separation, should guarantee that Turning movement and weaving volume are more less than all, single import and export are adopted in the processing of emphasis and through street connecting portion simultaneously, and the form turnover main line by branch/interflow improves the main line traffic capacity in this highway section.

Described preliminary when determining the interchange form, the ring road design objective is as follows:

(1) (partly) directed ring road that turns left: consider to allow to overtake other vehicles, prevent that the traffic capacity that the part slow-moving vehicle is delayed unloading to ring road from exerting an influence on ring road, for long distance, the ring road of longitudinal gradient, high absolute altitude should be arranged to two-way traffic greatly.The condition of setting is (partly) directed ring road that length surpasses 300m, and the volume of traffic is greater than 600pcu/h, and big-and-middle-sized car incorporation rate is not less than 20%.Consider safety problem simultaneously, the line of ring road river outlet is set to bicycle road inlet.

(2) loop ramp: the laying of loop ramp is bigger to the occupation of land influence of grade separation, should reduce the influence of grade separation satisfying under the efficiently current prerequisite of vehicle safety to urban land, therefore advise that the loop ramp radius of horizontal curve gets low value, R=50m, the loop ramp design speed is got 40km/h.

(3) right-hand rotation ring road: S type right-hand rotation ring road speed is higher than design rate, compares with standard form right-hand rotation ring road simultaneously, and its traffic capacity is more or less the same, and recommends to adopt when land used limits.

(4) ring road interflow: when two ring roads confluxed into a ring road, the track was reduced and is caused vehicle to scramble for roads travelling, easily cause ring road to block up.Back, suggestion ring road interflow number of track-lines is constant, pays attention to the processing of downstream ring road and main line junction simultaneously, guarantees lane balance.

Three: one city expressway interchanges of embodiment Selection and Design

According to the present situation volume of traffic or prognosis traffic volume, establish district's city expressway intersection, interior two two-way 8 tracks volume of traffic and carry out the analysis of steering flow primary and secondary planning to build: this crossing, place planning prediction in 2026 prospect traffic volume of planning to build upright interchange is shown in Figure 4.

According to the traffic capacity that obtains basic highway section, shunting zone, interflow district, interwoven region and all types of ring roads by realistic model, tentatively determine the form of interchange, this interchange form has following several scheme alternative:

Scheme one: combined I, shown in Fig. 5-1, this scheme is the diagonal angle form with loop ramp and is arranged in two quadrants, and other quadrant should adopt directed and semi-directional ring road according to the descending order of the volume of traffic.Grade separation has only shunting and interflow district, does not have interwoven region.This scheme cost estimate is 36,000 ten thousand yuan.

Scheme two: for clover blade profile grade separation, shown in Fig. 5-2, four quadrants in this scheme are loop ramp.Grade separation has interwoven region everywhere.This scheme cost estimate is 23,000 ten thousand yuan.

Scheme three: for combined I grade separation, shown in Fig. 5-3, this scheme is arranged in a direction with two loop ramps, simultaneously two main flow directions is made the semi-directional ring road.This scheme cost estimate is 32,000 ten thousand yuan.

Utilize aforesaid formula (3-1) to formula (3-5) to calculate the total traffic capacity of grade separation of above-mentioned three primary election schemes respectively:

The total traffic capacity of the grade separation of such scheme one is 25620pcu/h; The total traffic capacity of the grade separation of such scheme two is 23905pcu/h; The total traffic capacity of the grade separation of such scheme three is 30790pcu/h.

Planning to build grade separation place total volume of traffic in crossing in 2026 according to prediction is 17843pcu/h, as shown in Figure 6: the magnitude of traffic flow=(B+C+E+H) Pcu/h or (A+D+F+G) Pcu/h that this place is total; Wherein: A=M1+M2+M3; B=M4+M5+M9; C=M2+M7+M11; D=M8+M9+M10; E=M1+M6+M10; F=M4+M12+M11; G=M5+M6+M7; H=M3+M8+M12.

According to this prognosis traffic volume, compare respectively with the traffic capacity of above-mentioned various interchange forms, judge whether coupling, thereby determine the design proposal of the practicable interchange of a cover.Through checking computations, three scheme grade separation total wheel traffics are all greater than planning to build grade separation place crossing prognosis traffic volume in 2026.Wherein, scheme two is the most approaching.Consider the variability of prognosis traffic volume, traffic total amount come-up 20% back of prediction being planned to build the grade separation place is 21412pcu/h, and this is worth less than the total traffic capacity 23905pcu/h of scheme two grade separations, and the grade separation each several part all can satisfy the demand that turns to traffic in the scheme two.Therefore with the suggested design of scheme two as this crossing, place.In addition, scheme two costs reduce 13,000 ten thousand yuan than scheme one respectively, reduce 9,000 ten thousand yuan than scheme three.Therefore, think that scheme two is comparatively ideal relatively Selection and Design scheme.

Utilize design system of the present invention,, through street, Tianjin interchange has been carried out the simulation parameters demarcation according to interchange district field observation data.It is demarcated content and comprises vehicle divided lane branch vehicle desired speed, interflow district acceleration lane vehicle change trains model, interwoven region collector vehicle change trains model, typical vehicle acceleration and deceleration characteristic etc.The conclusions through measured value and simulation value, realistic model not only has good stability, and coincide better with the actual traffic stream mode, can be used as the traffic analysis platform in interchange district fully, be directly used in the traffic analysis of through street, Tianjin system.The foundation of Traffic Flow Simulation experiment porch can be analyzed the service level of planning to build interchange, and the traffic circulation situation of reproducing future directly perceived to find potential design defect, is convenient to propose innovative approach at problem.This is of great practical significance undoubtedly for the potentiality of saving investments in highway building, improving the facility effective utilization and excavating existing means of transportation.Certainly, on basis of the present invention,, can be widely used in the design of city expressway through adjusting correction factor.

In addition, it is worth noting: the speed of cart is influenced by longitudinal gradient mainly, and the cart operation will occasion a delay to other vehicles.Therefore in the grade separation design, should pay attention to analysis, suitably improve flat vertical standard for the too high direction of cart incorporation rate, to improve this place's traffic capacity to the cart incorporation rate.Also have, the outlet of interchange should be arranged on easy identification place, and unidirectional left and right commentaries on classics should be provided with unified outlet, and promptly the unidirectional gateway of grade separation should be unique.As unidirectional left and right when producing inlet and can not together come in and go out by the influence of landform, quantities, should guarantee first outlet for turning right, second outlet is for turning left, and rational traffic sign is set in time points out.

Although in conjunction with the accompanying drawings the present invention has been carried out foregoing description; but the present invention is not limited to above-mentioned embodiment; above-mentioned embodiment only is schematic; rather than it is restrictive; those of ordinary skill in the art is under enlightenment of the present invention; under the situation that does not break away from aim of the present invention, can also make a lot of distortion, these all belong to the row of protection of the present invention.

Claims (3)

1. city expressway interchange simulation design system, comprise data acquisition module, model calibration module and data outputting module, it is characterized in that, also comprise the evaluation analysis module that connects with model calibration module and data outputting module respectively, between evaluation analysis module and model calibration module, also be connected with the data correction module; The described Traffic Flow Simulation Models module of setting up comprises traffic stream characteristics theoretical model and traffic simulation software.

2. city expressway interchange simulation design system according to claim 1 is characterized in that: described data acquisition module comprises vehicle magnetic reflection traffic analysis, vehicle somatotype statistical system, GPS, video camera and computing machine; Described vehicle magnetic reflection traffic analysis adopts NC-97 type vehicle magnetic reflection traffic analysis, and described vehicle somatotype statistical system adopts MetroCount vehicle somatotype statistical system.

3. method of setting up city expressway interchange simulation design system model is characterized in that the method for utilizing simulation design system as claimed in claim 3 to set up model may further comprise the steps:

(A) utilize the data collecting module collected typical case to distinguish the following data of the interior basic highway section of interchange, branch/interflow district, interwoven region and ring road:

---the magnitude of traffic flow, the speed of a motor vehicle, length over ends of body, time headway and density;

---axletree is through speed, flow, time headway, wheelbase and the number of axle in the moment of sensor;

---locating information, travel speed, time and the driving trace of vehicle;

---road conditions, Turning movement, traffic composition and main line and ring road interleaving process, the vehicle position of changing trains;

---the acceleration-deceleration characteristic of typical vehicle is established changes in vehicle speed characteristic on the interior various ring roads in district with planning to build;

---utilize the data of data processor intercepting random time section in the GPS, behind the rejecting invalid data, generate coordinate and time data; Make the CAD figure of vehicle driving trace according to this coordinate and time data;

(B) draw the traffic stream characteristics data of actual traffic situation according to the above-mentioned data that collect;

(C) according to above-mentioned data scaling empirical model and the realistic model that collects, and set up forecast model, comprising:

(C-1) utilize the traffic stream characteristics theoretical model that the above-mentioned data that collect are carried out theoretical analysis;

---the basic capacity to basic highway section, shunting zone, interflow district and interwoven region carries out theoretical analysis:

According to becoming to follow the saturation headway between the two cars of front and back in the fleet of relaxation state mutually on two tracks in the shunting zone that collects, application of formula (1-1) is carried out the calculating of shunting zone and interflow district basic capacity respectively:

$C=\frac{3600}{\stackrel{\‾}{t}}---(1-1)$

In the formula (1-1): C---the branch/interflow district traffic capacity, pcu/h.,

---average minimum time headway, s;

The basic capacity of interwoven region: C _i=3600 λ _ImaxM _i(1-2)

$C=\underset{i}{\mathrm{\Σ}}{C}_i---(1-3)$

In formula (1-2) and the formula (1-3):

C---the total traffic capacity of interwoven region;

C _i---the traffic capacity in i track;

λ _Imax---the desirable maximum in the i track rate of sending a car, by formula ${\mathrm{\λ}}_{1\·\max }=\min \{{\widetilde{\mathrm{\λ}}}_{1\max },C_0\}$ And formula ${\mathrm{\λ}}_{2\·\max }=\min \{{\widetilde{\mathrm{\λ}}}_{2\max },C_0\}$ Determine, wherein: C ₀---the basic capacity in every track;

m _i---the possibility size that effective neutral in i track is utilized, determine by formula (1-4) and formula (1-5),

$m_2=1-\frac{Q_2\·r_2-{\tilde{Q}}^1}{Q_2\·r_2}$

$m_1=1-\frac{Q_1\·r_1-{\tilde{Q}}^2}{Q_1\·r_1}---(1-5)$

(C-2) demarcate empirical model and realistic model respectively according to the above-mentioned data that collect, comprising:

(1) according to the above-mentioned data that collect empirical model is demarcated and is revised, thereby set up following each regional forecast model:

Interchange shunting zone Forecasting Model of Density:

K _R＝0.484+0.00013Q _R+0.011Q ₁₂-0.0183L _D (2-1)

Interchange shunting zone speed prediction model:

V _R＝V _FF-(V _FF-50)(1.15+0.0002Q _R-0.008V _FR) (2-2)

Interchange interflow district Forecasting Model of Density:

K _R＝1.1+0.0059Q _R+0.0074Q ₁₂-0.01278L _A (2-3)

Interchange interflow district speed prediction model:

$V_R=V_{\mathrm{FF}}-(V_{\mathrm{FF}}-50)(0.78+0.01e^{(Q_{R12}/1000)}-0.004(L_A{V}_{\mathrm{FR}}/1000)---(2-4)$

The interchange interwoven region speed prediction model that interweaves:

$V_w=24+\frac{V_{\mathrm{FF}}-16}{1+\frac{0.0192{(1+Q_R)}^{7.21}{\left(\frac{Q}{N}\right)}^{1.133}}{{\left(3.28L\right)}^{0.8}}}---(2-5)$

The non-speed prediction model that interweaves of interchange interwoven region:

$V_w=24+\frac{V_{\mathrm{FF}}-16}{1+\frac{0.0178{(1+Q_R)}^{4.19}{\left(\frac{Q}{N}\right)}^{0.997}}{{\left(3.28L\right)}^{0.75}}}---(2-6)$

Above-mentioned formula (2-1) is to formula (2-6):

K _R---shunting zone and interflow district density, pcu/km/ln

Q---interwoven region total flow, pcu/h

Q _R---ring road flow, pcu/h

Q ₁₂---the main line outside two track flows, pcu/h

L---interwoven region length, m

L _A---acceleration lane length, m

L _D---deceleratuib lane length, m

V _R---shunting zone and interflow district speed, km/h

V _FF---main line free stream velocity, km/h

V _FR---ring road free stream velocity, km/h

V _W---the non-speed that interweaves, km/h

N---interwoven region number of track-lines;

(2) carry out the demarcation of Traffic Flow Simulation Models according to the above-mentioned data that collect;

(D) utilize the evaluation analysis module to judge that respectively the Traffic Flow Simulation Models of above-mentioned forecast model and demarcation compares with the traffic stream characteristics of actual traffic situation, its both error is≤10%;

If judged result is returned falsity, then return above-mentioned steps (C-2), demarcate empirical model and realistic model again;

If judged result is returned true value, order is carried out next step;

(E) determine capacity and level-of-service according to The above results, and export following index: the traffic capacity of determining basic highway section, shunting zone, interflow district, interwoven region and all types of ring roads by data outputting module.

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