Traffic congestion evaluation method based on congestion index
Traffic congestion evaluation method based on congestion index
 CN 103,366,557 B
 Filed: 07/25/2013
 Issued: 06/22/2016
 Est. Priority Date: 07/25/2013
 Status: Active Grant
First Claim
1. based on the traffic congestion evaluation method of congestion index, it is characterised in that comprise the steps:
 1) free stream velocity in each section in obtaining 24 hours, described free stream velocity is the travel speed of vehicle in the complete unimpeded situation of the less road of the volume of traffic；
2) calculating index TTI hourage in each section, described hourage, index was that vehicle travels the ratio of the time travelling same distance needs with free stream velocity with present speed；
3) according to hourage exponential quantity size the data in whole for road network sections a certain moment are carried out cluster analysis, the principle that in exponent data hourage of systemwide net is big as far as possible according to class inherited, class, difference is the least possible determines optimal classes；
4) on the basis determine optimal classes, index hourage in all sections of road network is clustered, and obtain the maximum TTI value of each class, minimum TTI Zhi Helei center TTI value；
5) for each class is asked it comprise the average of sample gradientnorm, all kinds of mapping range in congestion index are directly proportional to its gradientnorm, and congestion index scope 010 is distributed to each class；
6) step 5 give each hourage index class be assigned with on the basis that congestion index is interval, membership function is designed in each class, it is converted into congestion index according to the numerical value of certain rule each apoplexy due to endogenous wind index hourage, and blocks up weight situation with congestion index correspondence from small to large；
Wherein, in step 3, it is determined that the step of optimal classes is as follows;
If index hourage in ith section is sample a_{i}, then
Chinese PRB Reexamination
Abstract
The invention discloses a kind of traffic congestion evaluation method based on congestion index, comprise the steps: a, according to the free stream velocity in each section in the speed data calculating road network of road network vehicle equipment offer；B, calculate index hourage in every section；C, exponent data hourage to whole sections carry out cluster analysis and obtain number of categories；D, exponent data hourage to whole sections carry out cluster analysis, it is thus achieved that exponential quantity and class center exponential quantity hourage between the exponential quantity maximum hourage of each class, minimum traveltimes；E, each class is asked the average of its sample gradientnorm, distribute all kinds of corresponding congestion index scopes by the rule being directly proportional with gradientnorm；The congestion index that each apoplexy due to endogenous wind exponential number hourage is respectively mapped to such correspondence by f, definition membership function is interval。The inventive method can be adaptive to rain, snow, mist road passage capability change make decisions blocking up, science provide jam level divide。
5 Claims

1. based on the traffic congestion evaluation method of congestion index, it is characterised in that comprise the steps:

1) free stream velocity in each section in obtaining 24 hours, described free stream velocity is the travel speed of vehicle in the complete unimpeded situation of the less road of the volume of traffic； 2) calculating index TTI hourage in each section, described hourage, index was that vehicle travels the ratio of the time travelling same distance needs with free stream velocity with present speed； 3) according to hourage exponential quantity size the data in whole for road network sections a certain moment are carried out cluster analysis, the principle that in exponent data hourage of systemwide net is big as far as possible according to class inherited, class, difference is the least possible determines optimal classes； 4) on the basis determine optimal classes, index hourage in all sections of road network is clustered, and obtain the maximum TTI value of each class, minimum TTI Zhi Helei center TTI value； 5) for each class is asked it comprise the average of sample gradientnorm, all kinds of mapping range in congestion index are directly proportional to its gradientnorm, and congestion index scope 010 is distributed to each class； 6) step 5 give each hourage index class be assigned with on the basis that congestion index is interval, membership function is designed in each class, it is converted into congestion index according to the numerical value of certain rule each apoplexy due to endogenous wind index hourage, and blocks up weight situation with congestion index correspondence from small to large； Wherein, in step 3, it is determined that the step of optimal classes is as follows; If index hourage in ith section is sample a_{i}, then


2. the traffic congestion evaluation method based on congestion index according to claim 1, it is characterized in that, described step 1) in, 24 hours are divided into y equal interval, each section is calculated the average speed of vehicle in each interval, more respectively to each section before 24 hours ask speed maximum in y interior sample the average of 15% sample as the free stream velocity in this section。

3. the traffic congestion evaluation method based on congestion index according to claim 1, it is characterised in that described step 2) in, in the way of Floating Car, obtain relevant speed, and then obtain index hourage of respective stretch, adopt formula as follows:

4. the traffic congestion evaluation method based on congestion index according to claim 1, it is characterised in that described step 4) in index hourage in all sections of road network carried out cluster include following iterative processing steps:

(1) M is arbitrarily selected as initial cluster center from n sample； (2) calculate the distance of each sample and each class central point, and according to the principle of minimum range, sample is partitioned into a certain class； (3) calculate the center of each class, the central point of class be its arrive affiliated apoplexy due to endogenous wind other the minimum point of distance sum a little； (4) judge that whether each center and the last each center clustered of current cluster be consistent, such as inconsistent return step 2, as consistent finishing iteration has clustered。


5. the traffic congestion evaluation method based on congestion index according to claim 1, it is characterised in that described step 6) in membership function be S function that the change of class center is comparatively sensitive
Specification(s)