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Vehicle-vehicle Interactions at Roundabouts and their Implications for the Entry Capacity - A Methodological Study with Applications to Two-lane Roundabouts

Hagring, Ola LU (1998) In Bulletin / University of Lund, Lund Institute of Technology, Department of Traffic Planning and Engineering 159.
Abstract (Swedish)
Popular Abstract in Swedish

Avhandlingen behandlar kapacitet i cirkulationsplatser. Kapaciteten för ett körfält i en tillfart kan beräknas med teorin för kritiska tidsavstånd. Denna bygger på interaktioner mellan fordon med företräde (överordnade fordon) och fordon som skall lämna företräde (underordnade fordon). Det kritiska tidsavståndet är det minsta tidsavstånd mellan två överordnade fordon som en underordnad förare behöver för att korsa eller ansluta till den överordnade fordonsströmmen. Om det finns flera överordnade fordonsströmmar (såsom är fallet i en tvåfältig cirkulationsplats) brukar det kritiska tidsavståndet beräknas som om det vore endast en fordonsström. Detta görs genom att strömmarna överlagras. I... (More)
Popular Abstract in Swedish

Avhandlingen behandlar kapacitet i cirkulationsplatser. Kapaciteten för ett körfält i en tillfart kan beräknas med teorin för kritiska tidsavstånd. Denna bygger på interaktioner mellan fordon med företräde (överordnade fordon) och fordon som skall lämna företräde (underordnade fordon). Det kritiska tidsavståndet är det minsta tidsavstånd mellan två överordnade fordon som en underordnad förare behöver för att korsa eller ansluta till den överordnade fordonsströmmen. Om det finns flera överordnade fordonsströmmar (såsom är fallet i en tvåfältig cirkulationsplats) brukar det kritiska tidsavståndet beräknas som om det vore endast en fordonsström. Detta görs genom att strömmarna överlagras. I avhandlingen har en metod utarbetats för att skatta separata kritiska tidsavstånd för de olika överordnade fordonsströmmarna. Metoden, som är en maximum-likelihood metod, har testats genom simulering och visat sig ge tillförlitliga resultat. Den har sedan använts på data från svenska cirkulationsplatser. Det kan då visas att de kritiska tidsavstånden för de båda överordnade strömmarna skiljer sig åt (statistiskt signifikant) och att det kritiska tidsavståndet för den överordnade ström som är längst bort alltid är minst. Förare som befinner sig det högra körfältet i tillfarten och som inte interagerar med den bortre överordnade fordonsströmmen påverkas även av denna, vilket visar sig genom att det skattade kritiska tidsavståndet är stort (signifikant skilt från noll och i nivå med det kritiska tidsavståndet för den närmaste överordnade strömmen). (Less)
Abstract
Problem: The thesis deals with the capacity of two-lane roundabouts and with vehicle-vehicle interactions there.



Method: The interactions and the corresponding capacity are modelled by gap-acceptance theory. Various components of this theory are discussed, models for headways in the multi-lane case and for the estimation of critical gaps for the two major streams being developed and being applied to field data. The headway models were derived from renewal theory and were then applied to field data collected in Swedish roundabouts. Parameters of the headway distributions were estimated by maximum likelihood, the method of moments and least squares. The resulting distributions were tested by goodness-of-fit tests, using... (More)
Problem: The thesis deals with the capacity of two-lane roundabouts and with vehicle-vehicle interactions there.



Method: The interactions and the corresponding capacity are modelled by gap-acceptance theory. Various components of this theory are discussed, models for headways in the multi-lane case and for the estimation of critical gaps for the two major streams being developed and being applied to field data. The headway models were derived from renewal theory and were then applied to field data collected in Swedish roundabouts. Parameters of the headway distributions were estimated by maximum likelihood, the method of moments and least squares. The resulting distributions were tested by goodness-of-fit tests, using the D-statistic. Finally, a validation study was carried out.



The method for estimating of critical gaps was based on a maximum-likelihood model for a situation involving one major stream only. This model was extended to two major streams and was then tested by descriptive sampling and Monte Carlo simulation. Bootstrap was also used for control of the parameter estimates given by the model. Finally, the model was applied to field data from Swedish roundabouts.



Results: It was found that the Cowan M3 distribution could be employed for modelling the major flow in roundabouts, although in the validation test several of the samples were rejected. Minor-stream vehicles were impeded by vehicles in both the major streams. The strength of the impediment was measured by the size of the critical gaps. The critical gaps for a driver were significantly larger for the near major lane than for the far one, irrespective of which of the two minor lanes the driver was driving in. For driver turning to the right, the critical gap in the far lane was so large that it was evident that these drivers were influenced by drivers in the far lane, despite they not physically interacting with them. The correlation between the critical gaps was negative, a result that can be explained by some sort of risk compensation taking place or, what appears more likely, by ecological correlation. (Less)
Please use this url to cite or link to this publication:
author
opponent
  • Professor Troutbeck, Rod, Queensland University of Technology, Brisbane, Australia
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Samhällsvetenskaper, Social sciences, maximum likelihood, headways, critical gaps, driver behaviour, capacity, Gap acceptance, two-lane roundabouts, Technological sciences, Teknik
in
Bulletin / University of Lund, Lund Institute of Technology, Department of Traffic Planning and Engineering
volume
159
pages
208 pages
publisher
Department of Traffic Planning and Engineering, Lund Institute of Technology
defense location
V:A, John Ericssons väg 1, Lund, Sweden
defense date
1998-05-29 10:15
external identifiers
  • other:ISRN: LUTVDG/(TVTT-1016)/1-208/1998
ISSN
0346-6256
language
English
LU publication?
yes
id
295d87fb-a300-430b-b9a9-c5b0023a4a56 (old id 18865)
date added to LUP
2007-05-24 12:37:21
date last changed
2016-09-19 08:44:57
@phdthesis{295d87fb-a300-430b-b9a9-c5b0023a4a56,
  abstract     = {Problem: The thesis deals with the capacity of two-lane roundabouts and with vehicle-vehicle interactions there.<br/><br>
<br/><br>
Method: The interactions and the corresponding capacity are modelled by gap-acceptance theory. Various components of this theory are discussed, models for headways in the multi-lane case and for the estimation of critical gaps for the two major streams being developed and being applied to field data. The headway models were derived from renewal theory and were then applied to field data collected in Swedish roundabouts. Parameters of the headway distributions were estimated by maximum likelihood, the method of moments and least squares. The resulting distributions were tested by goodness-of-fit tests, using the D-statistic. Finally, a validation study was carried out.<br/><br>
<br/><br>
The method for estimating of critical gaps was based on a maximum-likelihood model for a situation involving one major stream only. This model was extended to two major streams and was then tested by descriptive sampling and Monte Carlo simulation. Bootstrap was also used for control of the parameter estimates given by the model. Finally, the model was applied to field data from Swedish roundabouts.<br/><br>
<br/><br>
Results: It was found that the Cowan M3 distribution could be employed for modelling the major flow in roundabouts, although in the validation test several of the samples were rejected. Minor-stream vehicles were impeded by vehicles in both the major streams. The strength of the impediment was measured by the size of the critical gaps. The critical gaps for a driver were significantly larger for the near major lane than for the far one, irrespective of which of the two minor lanes the driver was driving in. For driver turning to the right, the critical gap in the far lane was so large that it was evident that these drivers were influenced by drivers in the far lane, despite they not physically interacting with them. The correlation between the critical gaps was negative, a result that can be explained by some sort of risk compensation taking place or, what appears more likely, by ecological correlation.},
  author       = {Hagring, Ola},
  issn         = {0346-6256},
  keyword      = {Samhällsvetenskaper,Social sciences,maximum likelihood,headways,critical gaps,driver behaviour,capacity,Gap acceptance,two-lane roundabouts,Technological sciences,Teknik},
  language     = {eng},
  pages        = {208},
  publisher    = {Department of Traffic Planning and Engineering, Lund Institute of Technology},
  school       = {Lund University},
  series       = {Bulletin / University of Lund, Lund Institute of Technology, Department of Traffic Planning and Engineering},
  title        = {Vehicle-vehicle Interactions at Roundabouts and their Implications for the Entry Capacity - A Methodological Study with Applications to Two-lane Roundabouts},
  volume       = {159},
  year         = {1998},
}