Skip to main content

Capacity and Level of Service at Unsignalized Intersections Final Report Volume 1 - Two-Way-Stop-Controlled Intersections (1996) / Chapter Skim
Currently Skimming:

Chapter Three. Candidate Models
Pages 29-34

The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.


From page 29...
... of all inconsistencies found in the literature regarding the relationship of critical gaps to other parameters (such as traffic volumes, delays, delays at the stop line as service times of the imbedded queuing system, and geometric characteristics of intersections that are normally studied at different sites under different traffic volumes) might not actually exist but may instead result Dom inconsistencies in the estimation procedures.
Read the entire page →
From page 30...
... An iterative procedure provides an estimated critical gap, as well as the estimated variance of He critical gap. 6.0 5.9 - x x ,,,: x ~ 5.9 x x x x In x X x 58¢ x ~ y x x 5.7 x x xx 57 ~1 ~1 ~ 1 ~ 1 ~ 1 ~ 1 ~1 ~1 ~ 0 100 200 300 400 500 600 700 800 900 Major Street Volume, veh/hr ~ = S.8 sac x Estimated Values Figure 17.
Read the entire page →
From page 31...
... Both the Harders model and the Siegioch model yield nearly identical estimates of capacity despite somewhat different formulations. Troutbeck has extended both of these models to account for non-random or platooned major stream flow patterns and for multiple lanes on the major sheet.
Read the entire page →
From page 32...
... DELAY MODELS There are four general categories of models for estimating average vehicle delay at TWSC intersections: gap acceptance models, queueing theory models, empirical models, and hybrid models based on t~me-dependent flows. Models for estimating average vehicle delay based on gap acceptance theory were developed by Harders and SiegIoch.
Read the entire page →
From page 33...
... . theoretically sound easily validated with field data practical and easily applied by the practitioner produce sufficient and appropriate measures of effectiveness as output relevant in terms of common situations encountered by He practitioner.
Read the entire page →
From page 34...
... The theoredcal basis of the models based on gap acceptance theory lead to the selection of the SiegIoch and Harders models, wid1 ~e corrections proposed by Troutbeck to account for vehicle platoon~g for test~ng agamst field data. The emp~ncal models would be calibrated only if the gap acceptance models were subsequently found to inadequately replicate field data.
Read the entire page →

Key Terms

  • gap acceptance
  • major street
  • critical gaps
  • maximum likelihood
  • likelihood method

  • estimation procedure
  • street volume
  • acceptance theory
  • field data
  • delay models

  • estimation procedures
  • traffic volumes
  • acceptance models
  • twsc intersections
  • major stream

  • minor street
  • estimated values
  • subsequently found
  • estimating average
  • candidate models

  • estimation method
  • traffic streams
  • cntical gaps
  • state conditions
  • theoretically sound

  • capacity model
  • hue value
  • gap estimation
  • empirical models
  • flow patterns


    • This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
    More information on Chapter Skim is available.