Horizontal Alignment Design:

Transcription

1 High way and Transportation II (Lab.) LCIV 404 Lecture Horizontal Alignment Design: ) Circular curve) شت م ان ح األفق عه ثالثح ع اصز رئ ض ح: -1 خظ يضتق ى line) ) Straight - ي ح دائزي - ي ح ا تقان ( curve (Transition - تزصى ان اصاخ ضتط ع انحصىل عه انخطىط ان ضتق ح وأ ىجذ ان ح انذائزي و اال تقان - ع ذ رصى ان اصاخ تى رص ها قذر االيكا ف line) (Center انخاصح و أ ضا جة تقه م عذد ان اصاخ يع يزاعاج أطىل و أقصز خظ. نهشارع حتى ال تعذي عه ان هك اخ 1. Try to draw the tangents considering the following: - Minimize the number of tangents as possible - The tangents must approximately be at the center line of the suggested road - Maximum length of straight line in rural highway is (0Ve), Ve in km/hr. - Minimum length of straight line between two curves have the same direction of curvature is (6Ve), Ve in km/hr. - Minimum length of straight line between two curves have different direction of curvature is (0.00). 1

2 t ). تاصتخذاو ان قهح ( (g). Measure the total angle of deflection T c Yc T1 T m T0 T. Assume Ve then from diagram choose an approximate value for circular curve radius such that min max Ve ) )يىجىدج From page 4 in the lecture note, From the graph we can find the minimum and maximum values of by assuming the design velocity. min q max min 6%.5% حاول أ ال صم إن (7%=q) تم إن (6%=q) تذنك حصم عه ق ت ل عثزا ع Min, Max ختار ق ح ت هى و فضم أ تكى انق ح أقزب q max = 6 % = (0.06) إن max وي فش انشكم حصم عه q.

3 4. Design of Transition Curve: ان ح ى اال تقان هى ي ح ى زتظ ت انخظ ان ضتق ى و ان ح ى انذائزي ف ان ح ى األفق ونه عذج خىاص أه ها إعطاء تذرج ف ان م انعزض ت أقم ف ح نه ف انخظ ان ضتق ى إنى أعهى ق ح نه ف ان ح ى انذائزي ك ا عط تذرج ف عجهح انطزد ان زكزي ت أعهى ق ح ف ان ح ى انذائزي إنى اال عذاو ف انخظ ان ضتق ى. a V c V cons tan t For circular curve 0.00 For straight line Determiner A- value (Transition curve factor ),such /<A< Calculate the length of transition curve. L t = A / Calculate the angle of transition Curve ( t). Calculate the shift (Δ ). Lt 180 τ و فضم أ تكى أقزب إن () And: Lt 4 Calculate the total length of tangent ( PTo & PT). c Lt /C γ T ( )tan( ), 1.0 C c 1 τ τ 0 τ 10 Locate ( To,and T ) by measuring the distance PTo & PT from P on both the two tangents.

4 Set out the transition curve using: And ( max = c ) y 6 L t A ه م Example: Lt=00 step = 0 (or Lt=70 step=10 ) (m) c Y (cm) Design of Circular Curve: Set out the circular curve as the following. Calculate the circular curve angle (a) - Calculate the length of circular curve (LC) Check that L C Ve 1.8 Where V Lc 180 e in km/hr. ) انخظ ان ضتق ى) Calculate the length of long chord T 1 T T1T sin ( اصتخذو ان ضطزج نق اس طىل انىتز و قار ه تانق ح ان حضىتح ) 4

5 Set out the circular curve using following formula: Y - T1T - ( ) y T1 =0 T takes the value from o to (T 1 T /) (m) T 1 T / Y (cm) Summarize the results in table : A L t τ α T L c T 1 T

6 Example: Given that: Ve =80km/h g= 45 equired: design the horizontal alignment Solution: 1) Given that the maximum speed is V e = 80km\hr; and the angle = 45 o From diagram max = 110 m (80) min 9. 7m Use = 600m Design of transition curve ) / < A < or 600/ < A < 600 Use A = 400 m q = 4.5 % ( 40 m < < 110 m) ) L t = A / = 400 /600 Use L t = 66.67m 4) L τ 600 = 1.7 o 5) Check < < 8.6 o Ok 6) L t m γ c 7) PT o = PT = T ( )tan( ) 1.0 c Lt / C where C c Lt / / m 1 τ 0 10 τ 0 τ 10 6

7 T ( )tan( ) 8.84m T m 8) Setout the transition curve y 6 * L * t (m) c=64.5 Y (m) 0.08(10) (10) Design of circular curve 9) ) Lc 04.55m 180 L c = m. ( Lc > Ve/1.8 = ok) 11) T 1 T =T = sin( /) T1 T = 0.58 m T/ = m. 1).Setout the circular curve Y - - (T/) Y (m) Y (m) ) Summary. A L t τ α T L c T 1 T 600 m 400 m m 1.7 o o 8.84 m m 0.58 m 7