Volume List  / Volume 12 (3)



DOI: 10.7708/ijtte2022.12(3).03

12 / 3 / 322 - 339 Pages


Haitham A. Al Hasanat - Department of Highway and Railway Engineering, Faculty of Civil Engineering, Budapest University of Technology and Economics, H-1111 Budapest, Műegyetem rkp.3., Hungary -

Janos Juhasz - Department of Highway and Railway Engineering, Faculty of Civil Engineering, Budapest University of Technology and Economics, H-1111 Budapest, Műegyetem rkp.3., Hungary -


The gap acceptance method is one of the most widely used to analyze the capacity of roundabouts. The critical gap has a prominent role in this approach. In every country, driver behavior and local rules are examined and implemented in the local standard for capacity estimation. Hence, a reliable technique for assessing critical gaps can be of great importance. This paper presents an experimental investigation and analysis on whether it is possible to find the correlation between video-based gap acceptance parameters and some traffic parameters in Hungary. Thirteen single-lane roundabouts with different traffic flow rates were recorded for hours in various locations in and around Budapest to estimate the gap acceptance parameter (critical gap) and relate it to circulating and entry flow or the combination of both. Using only linear regression analysis, as a first step, no strong correlation was found between the critical gap and circulating flow and a lower correlation between the critical gap and entry flow. After implementation of a gradient boosted decision tree function, a stronger correlation was found between the critical gap and circulating flow, and an improved correlation between the critical gap and entry flow. The implemented correlation model shows a promising correlation between the critical gap and traffic parameters (circulating and entry flow). Our results indicate that the critical gap has a higher correlation with the circulating flow, and with the increase of the circulating flow, the critical gap value tends to decrease.

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