<abstract xmlns="http://www.w3.org/1999/xhtml">

<p>Spirally arranged and physically separated traffic lanes in the circulatory carriageway of turbo-roundabouts force drivers to choose a particular entry lane and, subsequently, a circulatory traffic lane according to their intended destination. This specificity is taken into account in theoretical capacity models for two-lane turbo-roundabout entries typically evaluated by the lane-by-lane approach. Nevertheless, this specific path of movements is not considered in the most widely used capacity models for single-lane minor entries at oval turbo-roundabouts. In these models, only one entering traffic flow conflicted by two circulating traffic flows in front of the entry is considered. However, the entering traffic flow presents a mixed traffic flow of two movements (right-turning movement and left-turning and through movement) with different capacities due to different number of conflicting traffic streams and traffic volumes allocated into the outer and the inner circulatory lane. This fact is included in the capacity estimation for a single-lane minor entry presented in the article using the existing capacity formula for the mixed traffic flow on a shared minor lane at unsignalized intersections. The entry capacity reflects the proportion of the right-turning movement within a shared entry lane as well as the specific allocation of circulating traffic flow into the outer and the inner circulatory lane. This entry capacity is about 10 % to 30 % higher compared to a single-lane entry capacity estimated according to commonly used models described in the article. Higher entry capacity in a higher proportion of the right-turning traffic within mixed entry traffic flow is confirmed also by the results of average delays estimated by the theoretical delay model and microsimulation.</p>
</abstract>

Spirally arranged and physically separated traffic lanes in the circulatory carriageway of turbo-roundabouts force drivers to choose a particular entry lane and, subsequently, a circulatory traffic lane according to their intended destination. This specificity is taken into account in theoretical capacity models for two-lane turbo-roundabout entries typically evaluated by the lane-by-lane approach. Nevertheless, this specific path of movements is not considered in the most widely used capacity models for single-lane minor entries at oval turbo-roundabouts. In these models, only one entering traffic flow conflicted by two circulating traffic flows in front of the entry is considered. However, the entering traffic flow presents a mixed traffic flow of two movements (right-turning movement and left-turning and through movement) with different capacities due to different number of conflicting traffic streams and traffic volumes allocated into the outer and the inner circulatory lane. This fact is included in the capacity estimation for a single-lane minor entry presented in the article using the existing capacity formula for the mixed traffic flow on a shared minor lane at unsignalized intersections. The entry capacity reflects the proportion of the right-turning movement within a shared entry lane as well as the specific allocation of circulating traffic flow into the outer and the inner circulatory lane. This entry capacity is about 10 % to 30 % higher compared to a single-lane entry capacity estimated according to commonly used models described in the article. Higher entry capacity in a higher proportion of the right-turning traffic within mixed entry traffic flow is confirmed also by the results of average delays estimated by the theoretical delay model and microsimulation.

Capacity Model for Single-Lane Minor Entry at Turbo-Roundabouts

Department of Highway Engineering, Faculty of Civil Engineering

Civil and Environmental Engineering

This work is licensed under the Creative Commons Attribution 4.0 International License.

{"article-title":"Capacity Model for Single-Lane Minor Entry at Turbo-Roundabouts"}

Spirally arranged and physically separated traffic lanes in the circulatory carriageway of turbo-roundabouts force drivers to choose a particular entry lane...

Capacity Model for Single-Lane Minor Entry at Turbo-Roundabouts

Published Online: Jun 22, 2021

Page range: 318 - 326

DOI: https://doi.org/10.2478/cee-2021-0033

Keywords
Capacity, Turbo-roundabout, Mixed traffic flow, Delay

© 2021 Andrea Kociánová, published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

Capacity Model for Single-Lane Minor Entry at Turbo-Roundabouts

Published Online: Jun 22, 2021

Page range: 318 - 326

DOI: https://doi.org/10.2478/cee-2021-0033

KeywordsCapacity, Turbo-roundabout, Mixed traffic flow, Delay

© 2021 Andrea Kociánová, published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

Keywords
Capacity, Turbo-roundabout, Mixed traffic flow, Delay