SVIBOR - Project code: 2-11-355


Strossmayerov trg 4, HR - 10000 ZAGREB
tel.: +385 1 459 44 44, fax: +385 1 459 44 69


SVIBOR - Collecting Data on Projects in Croatia

Project code: 2-11-355


Main researcher: RAKO, VICKO (40175)

Type of research: basic
Duration from: 01/01/91. to 12/31/95.

Papers on project (total): 18
Papers on project quoted in Current Contents: 1
Institution name: Građevinski fakultet, Zagreb (82)
Department/Institute: Department of Transportation Engineering
Address: Kačićeva 26, 41000 Zagreb
City: 10000 - Zagreb, Croatia
Fax: 385 (01) 416-621
Phone: 385 (01) 4561-222/356

Summary: Movement of vehicles within the test section is researched by a newly established method. Measurement of traffic flow is carried out on the highway section under ideal conditions with respect to roadway, traffic, and environment, respectively. Since every single vehicle is recorded according to type of vehicle, position of vehicle within a traffic flow, speed of vehicle, headway, and spacing, results of measurement enable us to establish correlation between these parameters from the aspect of highway capacity and traffic safety. The influence of both the time interval of measurement and division of traffic flow on the level of the highway capacity is established by iterative procedure. By changing the headway, which serves as a criterion for the defining of car-following within the platoon, the influence of that criterion on the rate of flow, and the highway capacity is established. The main, already known, traffic stream models are tested and new models are developed on the basis of the data evaluation comprising the relationships among the fundamental traffic stream variables. On the basis of the newly developed algorithms, and softwares and by integretion of the numerical and graphic analyses of the traffic, both the traffic within the test sections and the highway capacities are presented graphicaly. It has been assessed that the ideal capacity of a single traffic lane is 2,200 pcphpl while the ideal capacity of a two-lane two-way rural highway is 4,000 pcph.

Keywords: Highway capacity, level of service, traffic flow, fundamental traffic stream variables, measurements, traffic stream models, two-lane highway, platoon.

Research goals: This research is based on measurements and results of research ofthe traffic flow parameters on, and the capacity of, the two-lanehighways. Ideal flow which consists of passenger cars only, does not exist in the field. Consequently, up to now highway capacity is based on the hypothetical relationships within the traffic flow, i.e.,the highway capacity is assessed on the basis of correction of ideal conditions through the application of several adjustment factors. Divisions of traffic flow on a time basis that have been applied up to now used to include all fluctuation within the traffic flow, and did not provide the real basis for a highway capacity assessment. The combinations of traffic flow condition are defined by divisions of traffic flow on a functional basis, as well as from the aspect of car-following, thereby providing areal basis for highway capacity assessment. The purpose of this Project is to research the influence of each individual parameter on determination of the combinations of traffic flow condition and, indirectly, on highway capacity and the levels of service. A further aim of the Project is to provide a theoretical contribution to the study of regularity of vehicles moving within a traffic flow and to ensure the basis for generating the models of fundamental traffic stream variables on two-lane highway, as well as to define the combinations of traffic flow condition in real conditions, which is a prerequisite for forming platoons with mixed vehicles, and platoons with passenger cars only.

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Last update: 10/20/95