Turbo roundabouts are emerging innovative intersection control designs in the US that enhance traffic safety and operational efficiency. This study investigated driver’s speed choice, acceleration profiles, and behavioral parameters (critical gap and follow-up time) at the first rotor turbo roundabout in the US. Speed profiles revealed that vehicles’ speed at the approach and circulating lanes was affected by approach traffic arrival rates and traffic flow within circulating lanes. In addition, slower speed contributed to no speed-related crashes compared with past speed-related severe crashes before the turbo roundabout installation. Observed critical gaps (4.4–5.8 s) were higher than traditional multi-lane roundabouts (4.5–5.3 s). Follow-up time (3.7–4.7 s) was also higher than traditional multi-lane roundabouts, as drivers merged more cautiously in the circulating lanes owing to the raised lane dividers within the circular lanes. Drivers on the turbo roundabout’s inner lane exhibited longer critical gaps than those on the outer lanes owing to relatively complex merging events on the inner lanes, such as crossing multiple lanes to merge into the inner circulating lane. Merging vehicles’ gap acceptance was affected by the speed of vehicles on circulating lanes, merging vehicle type (e.g., passenger car, truck), and traffic flow rate on circulating lanes. Merging vehicles tended to accept larger gaps owing to the higher speed of vehicles on circulating lanes. As expected, heavy vehicles consistently accepted larger gaps than light vehicles. Conversely, higher traffic flow on circulating lanes caused merging drivers to accept shorter gaps after a longer wait time. Circulating lanes’ flow had a statistically significant effect on critical gaps compared with traditional roundabouts, possibly owing to raised lane dividers and local driving behavior. This study’s findings contribute to understanding the turbo roundabout’s performance in the US and the potential impacts of the turbo roundabout design features on capacity estimation and microsimulation considering US driver behavior.
GiuffrèO.GranàA.TumminelloM. L.Gap-Acceptance Parameters for Roundabouts: A Systematic Review. European Transport Research Review, Vol. 8, No. 2, 2016.
3.
RodegerdtsL. A.Roundabouts: An Informational Guide, Vol. 672. Transportation Research Board, Washington, D.C., 2010.
4.
ChodurJ.BąkR.Study of Driver Behaviour at Turbo-Roundabouts. Archives of Transport, Vol. 38, No. 2, 2016, pp. 17–28.
5.
CROW (Dutch Information and Technology Platform). Turbo Roundabouts, CROW Publication No. 257, Ede, Netherlands, 2008.
6.
EasaS. M.YouQ. C.Intersection Sight Distance Requirements for Basic Turbo Roundabouts. Journal of Transportation Engineering, Part A: Systems, Vol. 149, No. 2, 2022.
7.
TianZ.TroutbeckR. J.KyteM.BrilonW.VandeheyM.KittelsonW.RobinsonB.A Further Investigation on Critical Gap and Follow-Up Time. In 4th International Symposium on Highway Capacity: Proceedings, Transportation Research Circular E-C018, Transportation Research Board, National Research Council, Washington, D.C., 2000, pp. 397–408.
8.
RosaS.KocianovaA.Accuracy of Critical Gap Estimates. Alexandria Engineering Journal, Vol. 75, 2023, pp. 565–576.
9.
MacioszekE.Analysis of Significance of Differences between Psychotechnical Parameters for Drivers at the Entries to One-Lane and Turbo Roundabouts in Poland. In Intelligent Transport Systems and Travel Behaviour (G. Sierpiński, ed.), Advances in Intelligent Systems and Computing, Vol. 505, Springer, Cham, 2017, pp. 149–161.
10.
GuerrieriM.MauroR.ParlaG.TollazziT.Analysis of Kinematic Parameters and Driver Behavior at Turbo Roundabouts. Journal of Transportation Engineering, Part A: Systems, Vol. 144, No. 6, 2018.
11.
AhmedA.SadullahA. F. M.Yahya. SA.Field Study on the Behavior of Right-Turning Vehicles in Malaysia and Their Contribution on the Safety of Unsignalized Intersections. Transportation Research Part F: Traffic Psychology and Behaviour, Vol. 42, 2015, pp. 433–446.
12.
LuomaJ.SivakM.Interactions of Environmental and Safety Measures for Sustainable Road Transportation. European Transport Research Review, Vol. 4, No. 4, 2012, pp. 189–199.
13.
TraczM.ChodurJ.GacaS.Guidelines for the Design of Road Intersections – Part II. GDDP, Warszawa, Poland, 2001.
14.
Washington State Department of Transportation. Roundabouts, M 22-01.23, Design Manual, Chapter 1320. Olympia, WA, September 2024, pp. 1–34.
15.
FortuijnL. G. H.Turbo Roundabouts. Transportation Research Record, Vol. 2096, No. 1, 2009, pp. 16–24.
16.
SilvaA. B.MarianoP.SilvaJ. P.Performance Assessment of Turbo-Roundabouts in Corridors. Transportation Research Procedia, Vol. 10, 2015, pp. 124–133. https://doi.org/10.1016/j.trpro.2015.09.062.
17.
FernandesP.RouphailN. M.CoelhoM. C.Turboroundabouts Along Corridors: Analysis of Operational and Environmental Impacts. Transportation Research Record Journal of the Transportation Research Board, Vol. 2627, No. 1, 2017, pp. 46–56. https://doi.org/10.3141/2627-06.
18.
VasconcelosL.SilvaA. B.SecoÁ. M.FernandesP.CoelhoM. C.Turboroundabouts. Transportation Research Record Journal of the Transportation Research Board, Vol. 2402, No. 1, 2014, pp. 28–37. https://doi.org/10.3141/2402-04.
19.
FortuijnL. G. H.HoogendoornS. P.Capacity Estimation on Turboroundabouts with Gap Acceptance and Flow Level Methods. Transportation Research Record Journal of the Transportation Research Board, Vol. 2517, No. 1, 2015, pp. 71–79. https://doi.org/10.3141/2517-08.
20.
BrilonW.Some Remarks Regarding the Estimation of Critical Gaps. Transportation Research Record, Vol. 2553, No. 1, 2016, pp. 10–19.
21.
National Academies of Sciences, Engineering, and Medicine. Highway Capacity Manual, 7th Edition: A Guide for Multimodal Mobility Analysis. The National Academies Press, 2022.
22.
MacioszekE.Empirical Analysis of Gap Acceptance Parameters at Roundabouts Located in Tokyo (Japan) and the Tokyo Surroundings. In Nodes in Transport Networks - Research, Data Analysis and Modelling, TSTP 2019. Lecture Notes in Intelligent Transportation and Infrastructure (E. Macioszek, N. Kang, and G. Sierpiński, eds.), Springer, 2020, pp. 3–15.
23.
ShaabanK.HamadH.Critical Gap Comparison between One-, Two-, and Three-Lane Roundabouts in Qatar. Sustainability, Vol. 12, No. 10, 2020, p. 4232.
24.
RaffM. S.HartJ. W.A Volume Warrant for Urban Stop Signs. The Eno Foundation for Highway Traffic Control, Westport, CT, 1950.
25.
TupperS. M.KnodlerM. A.JrHurwitzD. S. Connecting Gap Acceptance Behavior with Crash Experience. In Proc., 3rd International Conference on Road Safety and Simulation, Indianapolis, 14–16 September 2011.
26.
PolusA.LazarS. S.LivnehM.Critical Gap as a Function of Waiting Time in Determining Roundabout Capacity. Journal of Transportation Engineering, Part A: Systems, Vol. 129, No. 5, 2003, pp. 504–509.
27.
FitzpatrickC. D.AbramsD. S.TangY.KnodlerM. A.Spatial and Temporal Analysis of Driver Gap Acceptance Behavior at Modern Roundabouts. Transportation Research Record, Vol. 2388, No. 1, 2013, pp. 14–20.
28.
DahlJ.LeeC.Empirical Estimation of Capacity for Roundabouts Using Adjusted Gap-Acceptance Parameters for Trucks. Transportation Research Record, Vol. 2312, No. 1, 2012, pp. 34–45.
FortuijnL. G. H.Turbo Roundabouts: Estimation of Capacity. Transportation Research Record, Vol. 2130, No. 1, 2009, pp. 83–92.
31.
MacioszekE.Models of Traffic Capacity in Roundabout Inlets in Ideal Conditions. Open Access Library, Vol. 3, No. 21, 2013, pp. 1–260.
32.
DeyK.NaikB.AshrafM. T.NdeogoB. I.HossenM. A. Investigating Implementation Potentials of Turbo Roundabouts in Nevada. West Virginia University, Department of Civil and Environmental Engineering, and Ohio University, Department of Civil and Environmental Engineering, Report 732-19-803. Nevada Department of Transportation, 2024.
33.
XuF.TianZ. Z.Driver Behavior and Gap-Acceptance Characteristics at Roundabouts in California. Transportation Research Record, Vol. 2071, No. 1, 2008, pp. 117–124.
34.
GazzarriA.MartelloM. T.PratelliA.SouleyretteR. R.Estimation of Gap Acceptance Parameters for HCM 2010 Roundabout Capacity Model Applications. WIT Transactions on the Built Environment, Vol. 1, 2012, pp. 309–320.
35.
HowardJ. P. E.Lessons Learned Designing California’s First Turbo Roundabout. Proc., Western District ITE 2022 Annual Meeting, Palm Springs, CA, 2022.
36.
PorterR.GoochJ.PeachK.ChestnuttC.MooreB.BroerenP.TigelaarJ.Advancing Turbo Roundabouts in the United States: Synthesis Report, Report No. FHWA-SA-19-027. Federal Highway Administration, Office of Safety, US Department of Transportation, Washington, D.C., 2019.
37.
RaisA. H.MunirR. Vehicle Speed Estimation Using YOLO, Kalman Filter, and Frame Sampling. In Proc., 2021 8th International Conference on Advanced Informatics: Concepts, Theory and Applications (ICAICTA), Bandung, Indonesia, 2021, pp. 1–6.
38.
JadhavA.PramodD.RamanathanK.Comparison of Performance of Data Imputation Methods for Numeric Dataset. Applied Artificial Intelligence, Vol. 33, No. 10, 2019, pp. 913–933.
39.
MillerA. J.Nine Estimators of Gap Acceptance Parameters. In Traffic Flow and Transportation: Proceedings of the 5th International Symposium on the Theory of Traffic Flow and Transportation, June 16–18, 1971, Berkeley, CA. Elsevier, New York, 1972.
40.
TroutbeckR.Estimating the Critical Acceptance Gap from Traffic Movements, Physical Infrastructure Center Report. Queensland University of Technology, Brisbane, 1992, Revised 2001.
41.
BrilonW.KoenigR.TroutbeckR. J.Useful Estimation Procedures for Critical Gaps. Transportation Research Part A: Policy and Practice, Vol. 33, No. 3–4, 1999, pp. 161–186.
42.
DrewD. R.Traffic Flow Theory and Control. McGraw-Hill, New York, 1968.
43.
BelzN. P.YangA.Utilization of Gaps at Single-Lane Roundabouts. Transportation Research Record, Vol. 2672, No. 34, 2018, pp. 1–9.
44.
SavolainenP. T.GatesT. J.GuptaN.Megat-JohariM.-U.CaiQ.ImosemiS.CeifetzA.McArthurA.HagelE. C.SmaglikE. J. Evaluating the Performance and Safety Effectiveness of Roundabouts – An Update. Report No. SPR-1725. Michigan Department of Transportation, Research Administration, Lansing, MI, 2023.
45.
HasanatH. A.JuhaszJ.The Influence of Circulating and Entering Flows on Critical Gaps Value in Roundabouts. International Journal of Traffic and Transportation Engineering, Vol. 12, No. 3, 2022, pp. 322–339.
46.
HeidemannD.WegmannH.Queueing at Unsignalized Intersections. Transportation Research Part B: Methodological, Vol. 31, No. 3, 1997, pp. 239–263.
47.
BakharevaN.TarasovV. Application of Two Forms of the Erlang Distribution Law in Queueing Theory. In Proc., 2021 IEEE 8th International Conference on Problems of Infocommunications, Science and Technology (PIC S&T), Kharkiv, Ukraine, 2021, pp. 639–642.
48.
PollatschekM. A.PolusA.LivnehM.A Decision Model for Gap Acceptance and Capacity at Intersections. Transportation Research Part B: Methodological, Vol. 36, No. 7, 2002, pp. 649–663.
49.
GuerrieriM.MauroR.TollazziT.Turbo-Round About: Case Study of Driver Behavior and Kinematic Parameters of Light and Heavy Vehicles. Journal of Transportation Engineering, Part A: Systems, Vol. 145, No. 6, 2019.
50.
YinS.LiZ.ZhangY.YaoD.SuY.LiL.Headway Distribution Modeling with Regard to Traffic Status. In Proc., 2009 IEEE Intelligent Vehicles Symposium, Xi'an, China, 2009, pp. 1057–1062.
51.
AkaikeH. Information Theory and an Extension of the Maximum Likelihood Principle. In Proceedings of the 2nd International Symposium on Information Theory (B. N. Petrov and F. Csáki, eds.), Akadémiai Kiado, Budapest, 1973, pp. 267–281.
AartsL.van SchagenI.Driving Speed and the Risk of Road Crashes: A Review. Accident Analysis & Prevention, Vol. 38, 2006, pp. 215–224.
54.
MalkhamahS.TightM.MontgomeryF.The Development of an Automatic Method of Safety Monitoring at Pelican Crossings. Accident Analysis & Prevention, Vol. 37, No. 5, 2005, pp. 938–946.
55.
KeshariS.MahmudM. S.PahariS.OverallM.BabićD.CavkaM.PremoS.GatesT. J.SavolainenP. T.Evaluating Driver Response to Bridge Deck Warning Systems During Winter Weather Conditions. Transportation Research Record: Journal of the Transportation Research Board, Vol. 2679, 2024, pp. 975–992.
