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SIGNALISED INTERSECTIONS

SIGNALISED INTERSECTIONS. TS4273 Traffic Engineering. First Traffic Light. Traffic lights were used before the advent of the motorcar. In 1868, British railroad signal engineer J P Knight invented the first traffic light, a lantern with red and green signals.

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SIGNALISED INTERSECTIONS

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  1. SIGNALISED INTERSECTIONS TS4273 Traffic Engineering

  2. First Traffic Light • Traffic lights were used before the advent of the motorcar. In 1868, British railroad signal engineer J P Knight invented the first traffic light, a lantern with red and green signals. • It was installed at the intersection of George and Bridge Streets in front of the British House of Commons to control the flow of horse buggies and pedestrians. http://www.didyouknow.cd/trafficlights.htm

  3. Prinsip-prinsip desain simpang bersinyal • Suatu persimpangan membutuhkan lampu lalulintas jika waktu tunggu rata-rata kendaraan sudah lebih besar daripada waktu tunggu rata-rata kendaraan pada persimpangan dengan lampu lalulintas.

  4. Prinsip-prinsip desain simpang bersinyal Waktu tunggu rata-rata kendaraan pada persimpangan bersinyal dipengaruhi oleh: • Arus lalulintas pada masing-masing arah, • Waktu antara kedatangan kendaraan dari masing-masing arah, • Keberanian pengemudi untuk menerima waktu antara yang tersedia guna menyeberangi jalan.

  5. Unsignalised Signalised Delay Traffic Flow Prinsip-prinsip desain simpang bersinyal

  6. Scope of IHCMSignalised Intersection Analyses • Isolated, fixed-time controlled signalised intersections with normal geometry layout (four-arm and three-arm) and traffic signal control devices. • Coordinated traffic signal control is normally needed if the distance to adjacent signalised intersections is small (< 200m).  Persimpangan Raya Darmo – Polisi Istimewa & Raya Darmo – RA Kartini.

  7. Objectives of IHCMSignalised Intersection Analyses • To avoid blockage of an intersection by conflicting traffic streams, thus guaranteeing that a certain capacity can be maintained even during peak traffic conditions;

  8. Objectives of IHCMSignalised Intersection Analyses • To facilitate the crossing of a major road by vehicles and/or pedestrians from a minor road; • To reduce the number of traffic accidents caused by collisions between vehicles in conflicting directions.

  9. Potential Conflict at Intersections

  10. Primary and Secondary Conflictis in a Four-Arm Signalised Intersections

  11. Street A Street B Time Sequence for Two-Phase Signal Control

  12. Time Sequence for Four-Phase Signal Control

  13. Street A Street B Time Sequence for Two-Phase Signal Control

  14. Purpose of the Intergreen Period • Warn discharging traffic that the phase is terminated.  Amber Period (for urban traffic signal in Indonesia is normally 3,0 sec) • Certify that the last vehicle in the green phase which is being terminated receives adequate time to evacuate the conflict zone before the first advancing vehicle in the next phase enters the same area.  All-Red Period

  15. Signal Phasing Arrangements • Introducing more than two phases normally leads to an increase of the cycle time and of the ratio of time allocated to switching between phases (especially for isolated and fixed-controlled).

  16. Signal Phasing Arrangements • Although this may be beneficial from the traffic safety point of view, it normally means that the overall capacity of the intersection is decreased.

  17. Basic Model for Saturation Flow (Akcelik 1989)

  18. Basic Model Saturation Flow • Discharge rate starts from 0 at the beginning of green and reaches its peak value after 10-15 sec • Effective Green = Displayed Green Time – Start Loss + End Gain • Start loss  End gain  4,8 sec (MKJI p.2-12) • Effective Green = Displayed Green Time

  19. Basic Model Saturation Flow • Base saturation flow is different between Protected approach and Opposed approach • For protected approach  S0 = 600 x We • For opposed approach  S0 in Indonesia usually lower where there is a high ratio of right turning movements, compare with Western models.

  20. Perhitungan Arus Jenuh Metode Time Slice Arus jenuh/jam  (3.600/5)x4,5 = 3.240 smp/jam Jika lebar lajur = 4,0m  (3.240/4) = 810 smp/jam/m Maka  S = 810 x We

  21. Traffic Safety Considerations • Traffic accident rate for signalised intersections has been estimated as 0,43 accidents/million incoming vehicles as compare to 0,60 for unsignalised intersections and 0,30 for roundabouts.

  22. STEP A-1: Geometric, Traffic Control and Environmental Conditions • General information (date, handled by, city, etc.) • City size (to the nearest 0,1 M inhabitants) • Signal phasing & timing • Left turn on red (LTOR) • Approach code • Road environment and level of side friction • Median • Gradient • Approach width (to the nearest tenth of a meter)

  23. Geometry of Signalised Intersection

  24. STEP A-2: Traffic Flow Conditions Q = QLV + (QHV x pceHV) + (QMC x pceMC)

  25. STEP B-1: Signal Phasing and Timing • If the number and types of signal phases are not known, two-phase control should be used as a base case. • Separate control of right-turning movements should normally only be considered if a turning-movement exceeds 200 pcu/h and has a separate lane.

  26. STEP B-1: Signal Phasing and Timing • Early start = leading green one approach is given a short period before the start of the green also in the opposing direction (usually 25%-33% from total green time) • Late cut-off = lagging green  the green light in one approach is extended a short period after the end of green in the opposing direction. • The length of the leading and the lagging green should not be shorter than 10 sec.

  27. STEP B-2: Intergreen time and lost time Only for planning purposes !!!

  28. STEP B-2: Intergreen time and lost time For operational and design analysis !!! • LEV, LAV distance from stop line to conflict point for evacuating and advancing vehicle (m) • lEV  length of evacuating vehicle (m) • VEV, VAV  speed of evacuating and advancing vehicle (m/sec)

  29. STEP B-2: Intergreen time and lost time • VAV  10m/sec (motor vehicles) • VEV  10m/sec (motor vehicles) • VEV  3m/sec (un-motorised) • VEV  1,2m/sec (pedestrians) • lEV  5m (LV or HV) • lEV  2m (MC or UM)

  30. STEP B-2: Intergreen time and lost time • IG  Intergreen = Allred + Amber • The length of AMBER usually 3,0 sec

  31. STEP C-1: Approach Type PROTECTED (P)  Discharge without any conflict between right-turning movements and straight-through/left-turning movements.

  32. STEP C-1: Approach Type • OPPOSED (O)  Discharge with conflict between right-turning movements and straight-through/left-turning movements from different approaches with green in the same phase.

  33. STEP C-2: Effective Aproach Width (We) Without LTOR • For Approach Type P (Q = QST) • If WEXIT We x (1 - pRT - pLT)  We = WEXIT

  34. STEP C-2: Effective Aproach Width (We) • If WLTOR≥ 2m (it is assumed that the LTOR vehicle can bypass the other vehicle)  We = min { (WA-WLTOR) , (WENTRY) } • For Approach Type P (Q = QST) If WEXIT < We x (1 – pRT)  We = WEXIT

  35. STEP C-2: Effective Aproach Width (We) • If WLTOR< 2m (it is assumed that the LTOR vehicle cannot bypass the other vehicle)  We = min { (WA) , (WENTRY+WLTOR) , (Wax(1+pLTOR)-WLTOR)} • For Approach Type P (Q = QST) If WEXIT < We x (1 – pRT – pLTOR)  We = WEXIT

  36. STEP C-3: Base Saturation Flow (S) • For protected approach

  37. STEP C-3: Base Saturation Flow (S) • For Approach Type P • S0 base saturation flow (pcu/hg) • We effective width (m) • Figure C-3:1 page 2-49

  38. STEP C-3: Base Saturation Flow (S) • For Approach Type O (opposed) • QRT and QRTO (Column 14 Form SIG-II opposed discharge right-turning) • Figure C-3:2 page 2-51 for approaches without separate right-turning. • Figure C-3:3 page 2-52 for approaches with separate right-turning. • Use interpolation if approach width larger or smaller than actual We

  39. STEP C-3: Base Saturation Flow (S) • Ex: without separate right-turning lane QRT = 125 pcu/h, QRTO = 100 pcu/h Actual We = 5,4m Obtain from Figure C-3:2 p. 2-51 (We=5 & We=6) S6,0 = 3.000 (pcu/hg) ; S5,0 = 2.440 (pcu/hg) Calculate; S5,4 =(5,4-5,0)x(S6,0 - S5,0)+ S5,0 =0,4(3.000-2.440)+2.440  2.660 (pcu/hg)

  40. STEP C-3: Base Saturation Flow (S) • If right-turning movement > 250 pcu/h, protected signal phasing should be considered • For No Separate RT-lane • If QRTO < 250 pcu/h • Determine SPROV for QRTO = 250 pcu/h • Determine Actual S as • S = SPROV – [(QRTO - 250) x 8]pcu/h

  41. STEP C-3: Base Saturation Flow (S) • For No Separate RT-lane • If QRTO > 250 pcu/h • Determine SPROV for QRTO and QRT= 250 pcu/h • Determine Actual S as • S = SPROV – [(QRTO + QRT - 500) x 2]pcu/h • If QRTO < 250 pcu/h and QRT > 250 pcu/h • Determine S as for QRT = 250 pcu/h

  42. STEP C-3: Base Saturation Flow (S) • For Separate RT-lane • If QRTO > 250 pcu/h • QRT < 250 pcu/h Determine S from Figure C3:3 through extrapolation • QRT > 250 pcu/h Determine SPROV as for QRTO and QRT= 250 pcu/h • If QRTO < 250 pcu/h and QRT > 250 pcu/h • Determine S from Figure C3:3 through extrapolation

  43. STEP C-4: City Size Adjustment Factor FCS [ Table C-4:3 p.2-53]

  44. STEP C-4: Side Friction Adjustment Factor FSF [ Table C-4:4 p.2-53]

  45. STEP C-4: Side Friction Adjustment Factor FSF [ Table C-4:4 p.2-53]

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