1. UNSIGNALISED INTERSECTIONS TS4273 Traffic Engineering

2. Scope and Objectives This chapter deals with 3-arm and 4-arm unsignalised intersections which are formally controlled by the basic Indonesian traffic code rule give-way to the left. This method assumes right angled intersections in flat alignment and is valid for degree of saturation less than 0,8-0,9.

3. Traffic Safety Considerations Effect of intersection layout –3-arm with T-shape 40% lower accident rates than 4-arm. –Y-shape have 15-50% higher accident rates than T-shape. Effect of geometric design –Median (3-4m) on major road reduces the accident rates (if the road wider than 10m)

4. Traffic Safety Considerations Effect of intersection control –Yield sign control reduces the accident rates 60% compare to priority from the left –Stop sign control reduces the accident rates 40% as compared to yield sign. –Traffic signal control reduces the accident rates 20-50% compared to uncontrolled operation.

5. Performance Measures of Unsignalised Intersections Capacity (C) Degree of saturation (DS) Delay Queue probability

6. Range of Variation in Empirical Data for Input Variables (4-Arm) VariableMin.Avg.Max. Approach width (m)3,55,49,1 Left-turn ratio0,100,170,29 Right-turn ratio0,000,130,26 Minor road flow ratio0,270,380,50 Light vehicle-%295675 Heavy vehicle-%137 Motorcycle-%193367 Unmotorised flow ratio0,010,080,22

7. Range of Variation in Empirical Data for Input Variables (3-Arm) VariableMin.Avg.Max. Approach width (m)3,54,97,0 Left-turn ratio0,060,260,50 Right-turn ratio0,090,290,51 Minor road flow ratio0,150,290,41 Light vehicle-%345678 Heavy vehicle-%1510 Motorcycle-%153254 Unmotorised flow ratio0,010,070,25

8. Definition of Unsignalised Intersection Types in IHCM (4-Arm) Type Code Major road approaches Minor road approaches No. of lanesMedianNo. of lanes 4221N1 4242N1 424M2Y1 4442N2 444M2Y2

9. Definition of Unsignalised Intersection Types in IHCM (3-Arm) Type Code Major road approaches Minor road approaches No. of lanesMedianNo. of lanes 3221N1 3242N1 324M2Y1 3442N2 344M2Y2

10. STEP A-1: Geometric Conditions Date Handle by City and province Major and minor road names Case Period Sketch of intersection geometry and dimension

11. STEP A-2: Traffic Condition Sketch of turning movement flow Traffic composition pcu-factor K-factor pce-values

12. STEP A-2: Traffic Condition

13. STEP A-3: Environmental Condition City Size (p.3-29 Table A-3:1 or p.3-34 Table B-5:1) Road Environment (p.3-29 Table A-3:2 or p.3-35 Table B-6:1) Side Friction (p.3-29 Table A-3:2 or p.3-35 Table B-6:1)

14. City Size Classes CS [Table A-3:1 p.3-29] City SizeInhab. (M) Very Small  0,1 Small > 0,1 -  0,5 Medium > 0,5 -  1,0 Large > 1,0 -  3,0 Very Large> 3,0

15. Road Environment Type RE [Table A-3:2 p.3-29] Commercial Commercial land use (e.g. shops, restaurants, offices) with direct roadside access for pedestrians and vehicles Residential Residential land use with direct roadside access for pedestrians and vehicles Restricted Access No or limited direct roadside access (e.g. due to the existence of physical barriers, frontage streets etc).

16. Side Friction class SF Side friction describes the impact of road side activities in the intersection area on the traffic discharge, e.g. pedestrians walking on or crossing the carriageway, angkot and buses stopping to pick up or let off passengers, vehicle entering and leaving premises and parking lots outside the carriageway. Side friction is defined qualitatively from traffic engineering judgment as high, medium or low.

17. STEP B-1: Approach Width and Intersection Type

18. Average intersection approach width, W I : W I = (a/2+b+c/2+d/2)/4 If A is only exit: W I = (b+c/2+d/2)/3 Road entry widths: W AC = (a/2+c/2)/2 W BD = (b+d/2)/2

19. STEP B-1: Approach Width and Intersection Type Average road approach width W AC,W BD (m) W BD = (b+d/2)/2 < 5,5 No. of lanes (total for both directions)  2 W AC = (a/2+c/2)/2  5,5 No. of lanes (total for both directions)  4

20. STEP B-1: Approach Width and Intersection Type Average road approach widths W AC, W BD and Average intersection approach width W I. W AC = (W A +W C )/2 and W BD = (W B +W D )/2 W I = (W A +W C +W B +W D )/no. intersection arms.

21. STEP B-1: Approach Width and Intersection Type IT Code No. of intersection arms No. of minor road lanes No. of major road lanes 322322 324324 342342 422422 424424

22. STEP B-2: Base Capacity Value C 0 Intersection TypeBase Capacity C 0 (pcu/h) 3222.700 3422.900 324 or 3443.200 4222.900 424 or 4443.400

23. STEP B-3: Approach Width Adjustment Factor F W 422  F W = 0,70 + 0,0866 W I 424 or 444  F W = 0,61 + 0,0740 W I 322  F W = 0,73 + 0,0760 W I 324 or 344  F W = 0,62 + 0,0646 W I 342  F W = 0,67 + 0,0698 W I

24. STEP B-3: Approach Width Adjustment Factor F W 422  F W = 0,70 + 0,0866 W I 424 or 444  F W = 0,61 + 0,0740 W I 322  F W = 0,73 + 0,0760 W I 324 or 344  F W = 0,62 + 0,0646 W I 342  F W = 0,67 + 0,0698 W I

25. STEP B-4: Major Road Median Adjustment Factor F M DescriptionType M Median adjustment factor, F M No major road median.None1,00 Major road median exists, width < 3m Narrow1,05 Major road median exists, width  3m Wide1,20

26. STEP B-5: City Size Adjustment Factor F CS City SizeInhab. (M)F CS Very Small  0,1 0,82 Small > 0,1 -  0,5 0,88 Medium > 0,5 -  1,0 0,94 Large > 1,0 -  3,0 1,00 Very Large> 3,01,05

27. STEP B-6: Road Environment, Side Friction & Unmotorised AF F RSU

28. STEP B-7: Left-Turning Adjustment Factor F LT

29. STEP B-8: Right-Turning Adjustment Factor F RT 4-arm 3-arm

30. STEP B-9: Minor Road Flow Ratio Adjustment Factor F MI 422 (p MI  0,1-0,9) F MI =1,19p MI 2 -1,19p MI +1,19 424 (p MI  0,1-0,3) F MI =16,6p MI 4 -33,3p MI 3 +25,3p MI 2 -8,6p MI +1,95 444 (p MI  0,3-0,9) F MI =1,11p MI 2 -1,11p MI +1,11

31. STEP B-9: Minor Road Flow Ratio Adjustment Factor F MI 322 (p MI  0,1-0,5) F MI =1,19p MI 2 -1,19p MI +1,19 322 (p MI  0,5-0,9) F MI =-0,595p MI 2 +0,595p MI +0,74 342 (p MI  0,1-0,5) F MI =1,19p MI 2 -1,19p MI +1,19 342 (p MI  0,5-0,9) F MI =2,38p MI 2 -2,38p MI +1,49

32. STEP B-9: Minor Road Flow Ratio Adjustment Factor F MI 324 (p MI  0,1-0,3) F MI =16,6p MI 4 -33,3p MI 3 +25,3p MI 2 -8,6p MI +1,95 344 (p MI  0,3-0,5) F MI =1,11p MI 2 -1,11p MI +1,11 344 (p MI  0,5-0,9) F MI =-0,555p MI 2 +0,555p MI +0,69

33. STEP B-10: Actual Capacity C

34. STEP C-1: Degree of Saturation DS

35. STEP C-2: Delays D (Intersection Traffic Delay DT I ) DS  0,60 DT I = 2 + 8,2078DS - (1-DS) 2 DS > 0,60 DT I = [1,0504/(0,2742-0,2042DS)] - (1-DS) 2

36. STEP C-2: Delays D (Major Road Traffic Delay DT MA ) DS  0,60 DT MA = 1,8 + 5,8234DS - (1-DS) 1,8 DS > 0,60 DT MA = [1,05034/(0,346-0,246DS)] - (1-DS) 1,8

37. STEP C-2: Delays D (Minor Road Traffic Delay DT MI ) DT MI = (Q TOTAL x DT I – Q MA x DT MA ) / Q MI

38. STEP C-2: Delays D (Intersection Geometric Delay DG) DS < 1,00 DG = (1-DS) x (p T x6 + (1-p T )x3) + 4xDS DS  1,00 DG = 4

39. STEP C-2: Delays D (Intersection Delay D) D = DG + DT I

40. STEP C-3: Queue Probability

41. STEP C-4: Evaluation of Traffic Performance If the obtain DS values are too high (> 0,75), we should revise our assumptions regarding approach width etc and make a new set of calculations.

42. Perbaikan Simpang Tak Bersinyal di Indonesia Perbaikan geometri (sudut & radius tikungan) Manajemen lalulintas (rambu & marka) Pengaturan PKL (represif & preventif) Pulau lalulintas (lebar jalan > 10 m) Lebar median di jalan utama (min 3-4 m)