Showing papers on "Traffic count published in 1981"

Simplified transport models based on traffic counts

Abstract: Having accepted the need for the development of simpler and less cumbersome transport demand models, the paper concentrates on one possible line for simplification: estimation of trip matrices from link volume counts. Traffic counts are particularly attractive as a data basis for modelling because of their availability, low cost and nondisruptive character. It is first established that in normal conditions it may be possible to find more than one trip matrix which, when loaded onto a network, reproduces the observed link volumes. The paper then identifies three approaches to reduce this underspecification problem and produce a unique trip matrix consistent with the counts. The first approach consists of assuming that trip-making behaviour can be explained by a gravity model whose parameters can be calibrated from the traffic counts. Several forms of this gravity model have been put forward and they are discussed in Section 3. The second approach uses mathematical programming techniques associated to equilibrium assignment problems to estimate a trip matrix in congested areas. This method can also be supplemented by a special distribution model developed for small areas. The third approach relies on entropy and information theory considerations to estimate the most likely trip matrix consistent with the observed flows. A particular feature of this group is that they can include prior, perhaps outdated, information about the matrix.

Hourly traffic volume patterns throughout the day in Melbourne

Abstract: In many urban road planning situations, for example evaluation models, it is necessary to have an indication of the hourly volume pattern throughout a day, but only the total daily volume and very little other information is available. This technical note presents a statistically based methodology for simplifying the hourly pattern by combining like hours. It also presents a simple regression model for predicting the flow in these hour groups and a strategy for incorporating growth of traffic volume. This study has been limited by the nature of the data base and it is therefore recommended that these models only be used in the absence of detailed traffic counting information (a).

The statistical assessment of transport data composed of counts

Abstract: This paper looks at an alternative method of analysis for transportation data in the form of counts which avoids the large sample problems present with other methods. Instead of examining whether the data could have been generated by a particular model or whether a particular model explains a significant amount of the data's variability the analysis tests whether the model is a sufficiently good approximation to reality. (Author/TRRL)

Analysis of routine traffic count stations to optimize locations and frequency

Abstract: This report describes a grouping of statewide permanent and key traffic counters on the basis of their geographic variations in traffic flow. Several factors were considered including the distance between clusters and urban versus rural areas. Traffic counts for a 3-year period were grouped into clusters by highway functional class for each individual parish. A computer program examines the maximum distance within a cluster and the maximum, average, and minimum distances within and between clusters. Count stations are arranged in clusters or groups of comparatively like counts. The cluster groups were examined by reviewing Louisiana parish maps that show the station locations. A computerized cluster analysis of all districts for 1977-1979 was reviewed according to highway functional classes 6, 7, and 8. An indepth review of the various cluster arrangements indicated the possibility of estimating the average annual daily traffic at some locations from sample traffic counts. A total of 111 stations could be measured less frequently by subjectively reviewing the location and proximity of the 2,290 stations, whereas a total of 1,246 stations could be read less frequently based on the objective but insensitive computerized cluster analysis. This observation confirms the need for further analysis by taking into consideration factors such as seasonal variations, geographic distribution of stations, and the number of stations existing in each cluster.

Analysis of routine traffic count stations to optimize locations and frequency : final report.

Abstract: This report describes a grouping of statewide permanent and key traffic counters on the basis of their geographic variations in traffic flow. Several factors were considered including the distance between clusters and urban versus rural areas. Traffic counts for a 3-year period were grouped into clusters by highway functional class for each individual parish. A computer program examines the maximum distance within a cluster and the maximum, average, and minimum distances within and between clusters. Count stations are arranged in clusters or groups of comparatively like counts. The cluster groups were examined by reviewing Louisiana parish maps that show the station locations. A computerized cluster analysis of all districts for 1977-1979 was reviewed according to highway functional classes 6, 7, and 8. An indepth review of the various cluster arrangements indicated the possibility of estimating the average annual daily traffic at some locations from sample traffic counts. A total of 111 stations could be measured less frequently by subjectively reviewing the location and proximity of the 2,290 stations, whereas a total of 1,246 stations could be read less frequently based on the objective but insensitive computerized cluster analysis. This observation confirms the need for further analysis by taking into consideration factors such as seasonal variations, geographic distribution of stations, and the number of stations existing in each cluster.