Traffic Flow Characteristics of an Urban Arterial Based on Different Traffic Flow Models

Four different single-regime traffic flow models (Greenshields, Northwestern, Underwood and Van Aerde) were used to develop fundamental diagram (FD) relations for an urban corridor segment in Ankara, Turkey. Fundamental diagrams were obtained using 1-min average speed and flow data digitized from 2-day video recording of the arterial segment. The model fits enabled the estimation of main traffic flow characteristics including free-flow speed (uf), jam density (kj), and flow, density and speed values at capacity (qcap, kcap, ucap). Performance of model fits was measured by R2 values, which were greater than 0.86 for all models. For lane-based fits, Van Aerde and Underwood performed better than other two models and showed significant variations among lanes in terms of uf, kj and qcap. Outermost lanes were expected to have higher uf and qcap values than inner lanes, reaching levels of 110 km/h and 2000 veh/h/ln, which are closer to intercity highway levels. Flow estimated by selected models had Mean Absolute Percentage Error (MAPE) mostly around 15% and Root Mean Square Error (RMSE) of 250 veh/h/ln; but Van Aerde model performed very well with MAPE and RMSE values less than 13% and 200 veh/h/ln, respectively. Furthermore, verification by site observation under early morning low volume and incident congestion situation supported the traffic flow estimates by Van Aerde model as the most flexible flow model successfully representing the limiting values under both free flow and very congested regimes.


Traffic Safety at Median Ditches: Steel vs. Concrete Barrier Performance Comparison Using Computer Simulation
Yücel, Ayhan; Atahan, Ali; Arslan, Turan; Sevim, Umur (MDPI AG, 2018-11-1)
In Turkey, concrete V-shaped ditches are formed at the median section of divided highways to provide drainage. Recent accidents show that these ditches actually present safety risks to vehicles entering the medians. Vehicles either cross over the ditch, roll over, or become trapped in the ditch, depending upon the mass, size, speed, and angle of the entering vehicle. To overcome this safety risk and reduce the severity of these accidents, longitudinal barriers are installed along these ditches. Currently, i...
Modeling truck traffic in Turkey
Fayyaz, Muhammad; Tüydeş Yaman, Hediye; Department of Civil Engineering (2015)
The objective of this study is to contribute to intercity road freight modeling in Turkey in general, and particularly estimation of origin-destination (O-D) matrix for intercity truck traffic, using the available freight transport data. As commodity flow data is not available for Turkey, information collected through roadside axle surveys is the main data source of this study. Firstly, the survey matrix has been estimated using roadside axle survey data from 2007-2011 period, and enlarged using link counts...
Displacement monitoring, displacement verification and stability assessment of the critical sections of the Konak tunnel, Izmir, Turkey
Yertutanol, Kadir; Akgün, Haluk; Sopaci, Evrim (Elsevier BV, 2020-07-01)
The main focus of this study is vertical displacement monitoring and verification along with preliminary support design for the four geotechnical sectors of the twin tube Konak tunnel that was constructed in a highly populated area in Izmir. The displacements of the tunnel that were obtained through numerical analysis were verified by comparing them with the displacements obtained by construction monitoring. In the study area, volcanics, pyroclastics and some sedimentary deposits (sandstone, mudstone and co...
Reliability based safety level evaluation of Turkish type precast prestressed concrete bridge girders designed in accordance with the load and resistance factor design method
Argınhan, Oktay; Caner, Alp; Yücemen, Mehmet Semih; Department of Civil Engineering (2010)
The main aim of the present study is to evaluate the safety level of Turkish type precast prestressed concrete bridge girders designed according to American Association of State Highway and Transportation Officials Load and Resistance Factor Design (AASHTO LRFD) based on reliability theory. Span lengths varying from 25 m to 40 m are considered. Two types of design truck loading models are taken into account: H30S24-current design live load of Turkey and HL93-design live load model of AASHTO LRFD. The statis...
Development of a Bridge Inspection and Management Project
Akgül, Ferhat (2010-09-24)
A research project is undertaken for the combined inspection and management of a pilot group of road bridges in Turkey based on the development of a bridge management system (BMS) for the General Directorate of Highways. The pilot study consists of visual inspections of 200 bridges and detailed inspections of 10 bridges. Visual inspections are planned to be carried out by photogrammetric techniques while detailed inspections will include techniques such as strength determination using probe test systems, ul...
Citation Formats
O. Altıntaşı, H. Tüydeş Yaman, and K. Tuncay, “Traffic Flow Characteristics of an Urban Arterial Based on Different Traffic Flow Models,” presented at the 13th International Congress on Advances in Civil Engineering, (12 - 14 Eylül 2018), İzmir, Türkiye, 2018, Accessed: 00, 2021. [Online]. Available: