1 / 12

Topic 5 Platoon and Dispersion

Topic 5 Platoon and Dispersion. TRANSYT-7F MODEL. TRANSYT is a computer traffic flow and signal timing model, originally developed in UK. TRANSYT-7F is a U.S. version of the TRANSYT model, developed at U of Florida (Ken Courage)

jermaine-haney
Download Presentation

Topic 5 Platoon and Dispersion

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Topic 5 Platoon and Dispersion

  2. TRANSYT-7F MODEL • TRANSYT is a computer traffic flow and signal timing model, originally developed in UK. • TRANSYT-7F is a U.S. version of the TRANSYT model, developed at U of Florida (Ken Courage) • TRANSYT-7F has an optimization component and a simulation component. • The simulation component is considered as a macroscopic traffic simulation, where vehicles are analyzed as groups. • One of the well known elements about TRANSYT-7F’s traffic flow model is the Platoon Dispersion model.

  3. WHY MODEL PLATOON DISPERSION? • Platoons originated at traffic signals disperse over time and space. • Platoon dispersion creates non-uniform vehicle arrivals at the downstream signal. • Non-uniform vehicle arrivals affect the calculation of vehicle delays at signalized intersections. • Effectiveness of signal timing and progression diminishes when platoons are fully dispersed (e.g., due to long signal spacing).

  4. PLATOON DISPERSION MODEL • For each time interval (step), t, the arrival flow at the downstream stopline (ignoring the presence of a queue) is found by solving the recursive equation

  5. PLATOON DISPERSION Flow rate at interval t, qt 100 % Saturation 50 0 Time, sec Start Green T = 0.8 * T’ Flow rate at interval t + T, Q(T+t) 100 % Saturation 50 0 Time, sec

  6. CLOSED-FORM PLATOON DISPERSION MODEL s Flow rate, vph v 0 tq tg Time C

  7. CLOSED-FORM PLATOON DISPERSION MODEL (1~tq) For 1~tq with s flow

  8. CLOSED-FORM PLATOON DISPERSION MODEL (0~tq) (1) (2) (1) – (2)

  9. CLOSED-FORM PLATOON DISPERSION MODEL (1~tq) For 1~tq with s flow Maximum flow downstream occurs at T+tq with upstream s flow

  10. BEYOND (1~tq) From the original equation: s no longer exists, but zero flow upstream t = tq +1 ~ ∞ • This is mainly to disperse the remaining flow, Qs,max. Upstream flow is zero • The same procedure for the non-platoon flow • The final will be the sum of the two

  11. EXAMPLE • Vehicles discharge from an upstream signalized intersection at the following flow profile. Predict the traffic flow profile at 880 ft downstream, assuming free-flow speed of 30 mph, α = 0.35; β = 0.8. Use time step = 1 sec/step 3600 Flow rate, vph 1200 0 16 28 Time C=60 sec

More Related