Summary of the invention
The object of the present invention is to provide a kind of section bottleneck recognition methods based on queuing sensor information.The detection information of detecting device of it is characterized in that queuing up is basis, to exceed number that the rolling time occupation rate of threshold value occurs continuously as discriminant criterion, section traffic behavior is carried out to real time discriminating, think in the time that queue length is more than or equal to the distance of queuing detecting device and stop line, the state at detector location place is bottleneck.
The basic thought of the method is in the time that section queuing tail of the queue approaches queuing detector location, follow-up arrival vehicle approaches by queuing detector speed the speed of blocking up, and can determine and characterize the contingent time occupancy threshold value of blocking up in conjunction with effective length of wagon of different automobile types; Utilize queuing detecting device under low state of saturation, to detect the traffic flow data obtaining, statistics obtains the rolling time occupation rate under unsaturated state; Take different positive integers as slip interval, the minimum value of getting rolling time occupation rate in sliding area forms new ordered series of numbers, and utilize Johnson curve to convert time occupancy ordered series of numbers to normal state data, and then utilize the basic thought of quality control chart to determine the upper control limit of the rolling time occupation rate composition sample that exceeds threshold value of different numbers; Upper control limit under comparative analysis time occupancy threshold value and different interval, choose the minimum number that makes the control chart upper limit be less than or equal to the desired continuous rolling time occupation rate that exceeds threshold value of time occupancy threshold value, the standard that must occur as bottleneck; Bottleneck trigger condition is the number that rolling time occupation rate is greater than threshold value continuously and is more than or equal to this standard.
To achieve these goals, the section bottleneck recognition methods that the present invention proposes comprises under the calculating of rolling time occupation rate, congestion status that rolling time occupation rate threshold value is determined, bottleneck trigger condition is determined several steps.
Concrete step comprises:
C1, detect the arithmetic for real-time traffic flow parameter in this this track of section of queuing detector acquisition of track section by need, and it is carried out to pre-service obtain rolling time occupation rate.
C2, determine according to the effective length of wagon of car and the compact car speed of blocking up the contingent rolling time occupation rate threshold value of blocking up.
In formula:
---characterize the contingent time occupancy threshold value of blocking up;
tj,c---the crowded holding time of car;
t---the time scale of rolling time occupation rate;
leff, c---the effective length of wagon of car;
uj,c---the car speed of blocking up.
C3, determine bottleneck activation threshold value, determine and can differentiate the number that the rolling time occupation rate must occur time of blocking up is greater than its threshold value continuouslyn.
C4, according to the corresponding threshold value index of bottleneck, judge whether section reaches bottleneck.
C5, according to the differentiation result of c4, if judgement arrive bottleneck, trigger bottleneck control strategy, otherwise jump to step c1.
Further, the process of obtaining arithmetic for real-time traffic flow parameter in step c1 comprises:
On c11, the inner side or middle lane of upstream, section detected at needs, lay queuing detecting device in the position apart from crossing, upstream 50m, and use the mode of electric wire, optical cable or radio communication to be connected with traffic surveillance and control center.
C12, determined the time scale of rolling time occupation rate by the crowded holding time of large cart.
In formula:tj,b---the crowded holding time of large car;leff, b---the effective length of wagon of large car;uj,b---the large car speed of blocking up.
C13, calculating rolling time occupation rate.Rolling time occupation rate is with △tfor rolling interval, calculate a series of continuous time intervalstinterior time occupancy.Its computing formula is as follows:
oi=ti/T
In formula:oi---theithe individual time intervaltinterior rolling time occupation rate;
ti---theithe individual time intervaltin, vehicle takies queuing detecting device duration.
Further, in step c3, use the thought of quality control chart, determined by enumerative techniquen.
Concrete definite method is:
C31, selectionn*(n*since 1 value) new samples of minimum value composition in individual continuous time occupation ratexn*.xn*in data can be represented by the formula:
The nonnormal sample data of time occupancy of obtaining in c32, step c31 is converted to normal state data.
C33, determine samplexn*upper control limit UCL, centre line C L and the lower control limit LCL of quality control chart.
C34, definite according to the parameter of gained quality control chartnvalue.
Further, in step c31, when the time by queuing detecting device, near detector location, must not get congestion with common speed owing to being less than car when rolling time occupation rate, work asoi<tf,c/ Ttime, this sample is rejected from overall, whereintf,ccar with free stream velocity by the holding time of queuing detecting device.
Further, step c32 has utilized Johnson curve to convert nonnormal data to normal state data.With the best Johnson curve distribution of Percentiles and Shapiro-Wilk or the definite fitting data of Epps-Pulley normal state check, and then according to Johnson curve, the rule of normal state conversion is become to normal state data by nonnormal rolling time occupation rate data-switching.
Concrete steps are:
C321, determine matching conversion valuez.In order to seek best matching conversion value, at best-fitzvalue possible rangeg{z:z=0.25,0.26 ..., the interior ascending one by one inspection of carrying out of 1.25}, step-length is 0.01, amounts to 101 numerical value.First orderzvalue is 0.25.
C322, calculate in standardized normal distribution corresponding to-sz,-z,z,szdistribution probabilityq1,q2,q3,q4.s> 1,suggestionsvalue is 3.
C323, estimation
xn*in sample, correspond respectively to
q1,
q2,
q3,
q4quantile
.
for data ascending order in sample arrange the
jindividual observed reading, wherein
j=
nqi+ 0.5 (
nfor sample size).When
jnon-when whole, can adopt method of interpolation to ask
.
In formula: mod is modulo operation symbol.
C324, calculating fractile ratio QR.
QR=mn/p2
In formula:
C325, determine Johnson converting system curve form according to QR, and utilizez,m,n,p,x-z,xzcarry out the parameter in estimation curve.Whereinx-zrepresent the 1-of standardized normal distributionzquantile;xzexpression standardized normal distributionzquantile.Calculation method of parameters in concrete curve is:
Work as QR<1, Johnson curve is Sbwhen system, each parameter value is as follows.
In formula:
for inverse hyperbolic function, wherein:
,
.
Work as QR>1, Johnson curve is Suwhen system, each parameter value following formula.
Work as QR=1, Johnson curve is Slwhen system, each parameter value following formula.
In above calculating formula
,
,
,
be all Johnson parameter of curve.Calculate after each parameter, utilize Johnson converting system to carry out normal state conversion to data.
C326, the data after normal state conversion are carried out to test of normality
Work as sample sizenwhen <50, adopt Shapiro-Wilk check.Now in the level of signifianceαunder, if according to the statistic of sample calculationw<w α(w αbew'sαfractile, can obtain by tabling look-up), refuse normality assumption.
Work as sample sizenwhen >50, adopt Epps-Pulley check, under insolation level α, according to sample statistictep determines whether to refuse normality assumption.tep normalized set formula is as follows.
If the statistic being calculated by sample datatePbe more than or equal toαfractile under level, refuses normality assumption.
If refusal normality assumption, willzvalue increases by 0.01, and returns to c322; If not refusing normality assumption exportszvalue and correspondingwortep value.
C327, output
wor
tin ep value, find out
wmaximal value or
tthe minimum value of ep, corresponding
zvalue is optimal fitting conversion values, and the conversion normal state data that calculate by this value are required data-switching result
.
Further, in step c33, the rolling time occupation rate sample obtaining by c32xn*normal state transformation result, can calculate samplexn*upper control limit UCL, centre line C L and the lower control limit LCL of quality control chart.Circular is as follows.
For Suand Slcurve, has:
For Sbcurve, has:
In formula:x0.5represent 0.5 quantile of standardized normal distribution;x0.00135represent 0.00135 quantile of standardized normal distribution;x0.99865represent 0.99865 quantile of standardized normal distribution.
Further, in step c34, contrast sample
xn*uCL and the rolling time occupation rate threshold value of quality control chart
if UCL is less than or equal to
, now
n*value is bottleneck activation threshold value
n; Otherwise will
n*value increases by 1, and returns to c31 and recalculate.
Further, in step c4, if rolling time occupation rate overtime occupation rate threshold valuecontinuous number be greater thann, section is in bottleneck, otherwise judges that section is not in bottleneck.
Beneficial effect of the present invention:
1, the discriminant criterion using rolling time occupation rate as bottleneck, has improved the real-time of bottleneck identification;
2, take the queuing detection information of bottleneck road as basis, can fundamentally change the hysteresis quality take upstream monitoring information as basic trigger condition, provide prerequisite for effectively avoiding queuing up to trace back;
3, the method mainly the analysis based on data obtain bottleneck activation threshold value, can react comparatively accurately actual traffic.
Embodiment
Below in conjunction with accompanying drawing, the present invention will be described in detail.
Bottleneck recognition methods of the present invention be queue up the detection information of detecting device be basis.The method can utilize the telecommunication flow information of real-time detection to analyze section traffic behavior, differentiates in time, accurately section bottleneck, for alleviating road section traffic volume pressure, avoid queuing up and trace back phenomenon basis is provided.
With reference to figure 1, illustrate the overall procedure of the present invention to bottleneck recognition methods.This bottleneck method of discrimination is made up of hardware and software two parts, the hardware devices such as its existing data acquisition equipment, teleseme and server, have also had that rolling occupation rate is calculated, bottleneck activation threshold value is determined and judge whether to reach the computer program part of bottleneck.This bottleneck recognition methods is on the basis of queuing sensor information, realize by self-editing computer program, complete says, the judgement of determining, whether trigger bottleneck of the determining of the collection of its detecting device that comprises the steps: to queue up to traffic flow parameter, the calculating of rolling time occupation rate, the contingent rolling time occupation rate threshold value of blocking up, bottleneck activation threshold value.To the bottleneck recognition methods based on queuing sensor information be explained in detail according to time sequencing below:
Step 1, installation hardware
With reference to figure 2, queuing detecting device is installed on section.Concrete realization queuing detecting device gathers and needs to install following hardware device transport information parameter:
detecting on section, on the middle lane (or inside lane) apart from 50m place, crossing, upstream, bury the queuing detecting device that design specification is 2 × 2m underground, for the parameter information of acquisition time occupation rate.
utilize existing teleseme, server, and queuing detecting device and stream signal machine are coupled together with electric wire and/or optical cable, then teleseme and server are coupled together with electric wire and/or optical cable.
Step 2, calculating rolling time occupation rate
After section telecommunication flow information being gathered by queuing detecting device, utilize the information gathering to calculate calculating rolling time occupation rate, step is as follows:
determined the time scale of rolling time occupation rate by the crowded holding time of large car
t.
In formula:tj,b---the crowded holding time of large car;leff, b---the effective length of wagon of large car;uj,b---the large car speed of blocking up;t---the time scale of rolling time occupation rate.
rolling time occupation rate is with △tfor rolling interval, calculate a series of continuous time intervalstinterior time occupancy.Theiindividual time occupancy computing method as shown in the formula.
oi=ti/T
In formula:oi---theithe individual time intervaltinterior rolling time occupation rate;ti---theithe individual time intervaltin, vehicle takies queuing detecting device duration.Fig. 3 be witht=5 △tfor example explanationtistatistical method.
Step 3, calculate the contingent rolling time occupation rate threshold value of blocking up
Determine and characterize the contingent rolling time occupation rate threshold value of blocking up according to the effective length of wagon of car and the compact car speed of blocking up.
In formula:
---characterize the contingent time occupancy threshold value of blocking up;
tj,c---the crowded holding time of car;
leff, c---the effective length of wagon of car;
uj,c---the car speed of blocking up.
Determining of step 4, bottleneck activation threshold value
Single rolling time occupation rate can not represent near traffic behavior detecting device, in order to determine more accurately that whether section is in bottleneck, needs to determine to represent near exceeding of the traffic behavior of detecting device
the number that occurs continuously of rolling time occupation rate
n.
While there is not supersaturation due to bottleneck road, the get congestion probability of phenomenon of queuing detecting device place is very low, can represent that the UCL of the rolling time occupation rate control chart of queuing detector location place traffic behavior should be not more than
, therefore determining
ntime, from
n*=1 starts to enumerate, if do not satisfy condition
n* value increases by 1 and continues computing, until
n* arrive certain numerical value, the UCL of the quality control chart being obtained by this numerical value is less than or equal to
, now
n*value is required
nvalue.
Moreover, due to the non-normality of rolling time occupation rate sample, need to utilize Johnson curve to carry out normalize to data, and its first step is to seek best matching conversion values.
Here with reference to figure 4, the concrete steps of definite bottleneck activation threshold value have been provided.
selectn*(n*since 1 value) new samples of minimum value composition in individual continuous time occupation ratexn*.xn*in data can be represented by the formula:
When time occupancy by queuing detecting device, near detector location, must not get congestion with free stream velocity owing to being less than car when rolling time occupation rate, work asoi<tf,c/ Ttime, this sample is rejected from overall, whereintf,ccar with free stream velocity by the holding time of queuing detecting device.。
determine matching conversion value
z.In order to seek best matching conversion value, at best-fit
zvalue possible range
g{
z:
z=0.25,0.26 ..., the interior ascending one by one inspection of carrying out of 1.25}, step-length is 0.01, amounts to 101 numerical value.First order
zvalue is 0.25.
calculate in standardized normal distribution corresponding to-sz,-z,z,szdistribution probabilityq1,q2,q3,q4.Whereins> 1, suggestionsvalue is 3.
estimate
xn*in sample, correspond respectively to
q1,
q2,
q3,
q4quantile
.
for data ascending order in sample arrange the
jindividual observed reading, wherein
j=
nqi+ 0.5 (
nfor sample size).When
jnon-when whole, can adopt method of interpolation to ask
.
In formula: mod is modulo operation symbol.
calculate fractile ratio QR.
QR=mn/p2
In formula:
determine matched curve form according to QR, and estimate response curve correlation parameter and carry out normal state conversion.Several translation types of Johnson curve and various types of restriction on the parameters and variable-value scope are as shown in table 1.
Table 1 Johnson converting system
Parameter in curve can be utilizedz,m,n,p,x-z,xzestimate, whereinx-zrepresent the 1-of standardized normal distributionzquantile;xzexpression standardized normal distributionzquantile.
Work as QR<1, Johnson curve is Sbwhen system, each parameter value is as follows.
In formula:
for inverse hyperbolic function, wherein:
,
.
Work as QR>1, Johnson curve is Suwhen system, each parameter value following formula.
Work as QR=1, Johnson curve is Slwhen system, each parameter value following formula.
Calculate after parameters, can be right according to table 1xn*carry out normal state conversion.
, the data after Johnson conversion are carried out to test of normality
Work as sample sizenwhen <50, adopt Shapiro-Wilk check.Now in the level of signifianceαunder, if according to the statistic of sample calculationw<w α(w αbew'sαfractile, can obtain by tabling look-up), refuse normality assumption.
Work as sample sizenwhen >50, adopt Epps-Pulley check, under insolation level α, according to sample statistictep determines whether to refuse normality assumption.tep normalized set formula is as follows.
If the statistic being calculated by sample datatePbe more than or equal toαfractile under level, refuses normality assumption.
If refusal normality assumption,
zvalue increases by 0.01, and returns
; If accepting normality assumption exports
zvalue and corresponding
wor
tep value.
what export
wor
tin ep value, find out
wmaximal value or
tthe minimum value of ep, corresponding
zvalue is optimal fitting conversion values, and the conversion normal state data that calculate by this value are required data-switching result
.
the small probability event territory identical according to Shewhart control chart, CL, the LCL of control chart and UCL should be respectively on probability is 0.5,0.00135 and 0.99865 fractile.Therefore, when
svalue is 3 o'clock, and in standardized normal distribution, three are divided into accordingly number and correspond respectively to z=0, z=-3, the position of z=3, and can determine corresponding fractile according to the inverse function of normal state transfer function
x0.5,
x0.00135,
x0.99865.
According to final normalize result
the Johnson parameter of curve calculating, can calculate sample
xn*upper control limit UCL, centre line C L and the lower control limit LCL of quality control chart.Circular is as follows.
For Suand Slcurve, has:
For Sbcurve, has:
contrast sample
xn*quality control chart upper bound UCL value and rolling time occupation rate threshold value
if UCL is less than or equal to
,
n*value is bottleneck activation threshold value
n; Otherwise will
n*value increases by 1, and returns
recalculate.
Step 5, judge that rolling time occupation rate is greater than time occupancy threshold value
continuous number whether be greater than
nif judge that section, in bottleneck, should implement bottleneck control strategy, otherwise judge that section is not in bottleneck.