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CE 578 Highway Traffic Operations

CE 578 Highway Traffic Operations. Lecture 7: Two-lane highway performance. Objectives. Application of operations performance measures Relate measures to field observation Roughly identify means to obtain measures. What are we trying to do with performance measures?.

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CE 578 Highway Traffic Operations

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  1. CE 578 Highway Traffic Operations Lecture 7: Two-lane highway performance

  2. Objectives • Application of operations performance measures • Relate measures to field observation • Roughly identify means to obtain measures

  3. What are we trying to do with performance measures? • How well does the facility serve the public? • Assess performance that addresses different issues • passing demand and supply • speed impeded by geometry • speed impeded by traffic

  4. How should we obtain two-lane highway performance? • field measurement • expensive • only for existing facilities • closer to reality • modeling • more cost effective • supports alternative analysis • must be validated

  5. What are some useful performance measures? • Average Travel Speed (ATS) • Percentage of free flow speed (PFFS) • Percent Time Spent Following (PTSF) • Percent delay (PD)

  6. Roadway and Traffic Stream Characteristics • horizontal curves impeding speed • horizontal curves impeding sight distance • vertical curves impeding sight distance • grade impeding vehicle performance • entering traffic • exiting traffic • intersection traffic control (yield, stop, signalized) • passing traffic control • auxiliary lanes • traffic volume • opposing traffic volume • heavy vehicles

  7. How do we accommodate varying characteristics? • Create highway homogenous segments • Homogeneous operational effects within a segment • Possess input data required to assess performance

  8. Defining Segments and Their Borders? • Grade • Intersection • Auxiliary lanes • Horizontal curves • Passing zones • Volume level

  9. Modeling Performance • Stochastic micro-simulation • Washburn • TWOPAS • Paramics • Deterministic model • Romana • Poulus • Troutbeck • Highway Capacity Manual (HCM)

  10. Assignment • Stochastic micro-simulation • Read paper by Yu • How does this paper address the problem non-homogeneous highway characteristics? • What additional segment types would you add, in addition to the ones they define? Why? • Deterministic model • Read paper by Romana • Why would a speed-flow model be useful? Does this one look reasonable? Explain. • Read paper by Polus • What is(are) the performance measure(s) that Polus proposes? • What are the steps that you would take to implement them?

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