karakteristik kendaraan
DESCRIPTION
materiTRANSCRIPT
Karakteristik FisikA. Tipe
i. Fast moving vehicleii. Slow moving vehicle
B. Dimensi penting untuk design geometrik jalanC. Turning Radius
i. Low speed turn kurang dari 16 km/jam tergantung pada jejak roda dan sudut perputaran.
ii. High speed turn tergantung pada superelevasi dan side friction
Gambar 1. Turning Radius Kendaraan Penumpang
Gambar 2. Turning Radius dari Truk
fevR
127
2
R = radius of curve (m)v = speed of vehicle (km/jam)e = rate of superelevationf = coeficient of side friction
D.D. DesainDesain Desain kendaraan sehubungan dengan Desain kendaraan sehubungan dengan
kemampuan melihat pengemudi dan letak kemampuan melihat pengemudi dan letak lampu harus diperhitungkan pada penentuan lampu harus diperhitungkan pada penentuan penerangan jalan.penerangan jalan.
Tabel 1. Vehicle Characteristic Affecting Road FeaturesVehicle Characteristic Affecting Elements Width of Vehicle Lane width, width of shoulders, width of
parking lots. Length of Vehicle Horizontal alignment, minimum turning
radius, extra widening on curves, passing sight distance, road capacity, parking facilities.
Height of Vehicle Clearance to be provided under bridges, subways, electric service lines, etc.
Weight of Vehicle Pavement thicness, rolling and limiting gradients, design of road bridges.
Turning Radius of Vehicle Parking manouvers, curves, intersection design, channelisation driveways, etc.
Speed of Vehicle Horizontal and vertical alignment, superelevation, limiting radius, sight distance, lane capacity, intersection design, skid resistance.
Power of Vehicle Rolling and limiting gradient, speed of vehicle in conjunction with various resistance, braking resistance.
Acceleration characteristics Time required to cross intersection, passing a vehicle, gap acceptance.
Braking characteristics Stopping distance, overtaking sight distance, traffic capacity.
Head lights of Vehicle Night operation, night accidents.
Tabel 2. Typical Maximum Dimensions and Wights of Motor Vehicles
No. Particulars Maximum limits1. Width 2.6 m 8.5 ft
2. Height 4.1 m 13.5 ft
3.
Length :Single unit truckBusTruck tractor and semi trailerOther combination
12.2 m12.2 m
16.75 m19.8 m
40 ft40 ft55 ft65 ft
4.Axle load :SingleTandem
9.1 m.t15.4 m.t
10 t17 t
5.
Maximum gross weight :2 axle truck3 axle truck3 axle combination4 axle combination5 axle combination6 axle combination
13.6 m.t13.4-20 m.t
19.0-22.7 m.t22.7-31.8 m.t32.4-38.1 m.t37.6-40.8 m.t
15 t17-22 t21-25 t25-35 t
35.8-42 t41.5-45 t
Tabel 3. AASHTO Design Vehicle Dimensions in Feet (1 ft = 0.305 m)
Design Vehicle Type
Symbol
Wheel Base
Front Overhan
g
Rear Overhan
g
Overall Length
Width Height
Passenger Car P 11 3 5 19 7 -
Single Unit Truck SU 20 4 6 30 8.5 13.5
Single Unit Bus BUS 25 7 8 40 8.5 13.5
Semi Trailer Combination (Intermediate)
WB-40 40 4 6 50 8.5 13.5
Semi Trailer Combination (large)
WB-50 50 3 2 55 8.5 13.5
Semi Trailer Full Trailer Combination
WB-60 60 2 3 65 8.5 13.5
Tabel 4. Wheel Path of Design Vehicle
Type of AASHTO Vehicle Minimum Turning Radius Minimum Inside Radius
P 24 ft 7.32 m 15.3 ft 4.67 mSU 42 ft 12.8 m 28.4 ft 8.66 m
BUS 42 ft 12.8 m 20.3 ft 6.19 mWB-40 40 ft 12.2 m 19.9 ft 6.06 mWB-50 45 ft 13.72 m 19.8 ft 6.03 m
WB-60 45 ft 13.72 m 22.5 ft 6.86 m
2.2. Karakteristik Operasional
A. Resistances and Power Requirementi. Inertia Force = mass x acceleration
Fi = mass x accelerationii. Rolling Resistance (Rr)
terjadi karena :Surface roughness of pavementIrregularities of road surfaceFriction in the moving path of vehicle
Tergantung pada tipe jalan meningkatpada jenis jalan berikut (Tabel 5) pada
kecepatan konstan (100 km/jam).
Type of surface Rolling resistance (lb/ton)
Cement concreteBituminous concreteUntreated gravelLoose gravelSoft wet ground
19202750120
iii. Air Resistance (Ra) Tergantung Pada :
Density of airSpeed of vehicleFrontal area of vehicleDirection of wind
Tabel 5. Tipe perkerasan jalan dan besar rolling resistance
Rumus : 2vAKRa Ra = air resistanceK = konstanta = 0.0017A = frontal area of vehiclev = velocity of vehicle
iv.Grade Resistance (Rg)Gaya gravitasi sebanding dengan kemiringan jalan dan berat kendaraan.Diekspresikan : 20 lbs/ton berat kendaraan per % grade.
Power RequirementPenting untuk peningkatan kecepatan dan di daerah tanjakan.Total horse power req = HP Rr + HP Ra + HP RgTotal HP
375
0017.020
55047.12047.10017.0()47.1
3
2
AVGRrVWHP
VGWVAVVWRrHP
W = berat vehicle (tonnes)V = speed (mph)Rr = rolling resistance (lbs/tonne)A = frontal area (sq – ft)G = percent gradient
B. Breaking AbilityJarak yang dibutuhkan untuk berhentinya kendaraan tergantung pada : Berat Kendaraan Tingkat Pengereman
tan2
2
fgVDb
Db = breaking distanceg = acceleration terhadap gravitasif = koefisien friksiv = speedtan = slope of gradien (G) + ….. , – …..
C. Karakteristik PercepatanData percepatan digunakan untuk menentukan karakteristik kendaraan pada situasi : Melintasi persimpangan Jarak yang dibutuhkan untuk menyiap Jarak aman, dan sebagainya
Ada 2 (dua) type percepatan :
a) Uniform Acceleration Theory
aVV
S
attVS
atVV
O
O
O
2
21
22
2
V = final speedVO = initial speeda = accelerationt = timeS = distance travelled
b) Non Uniform Acceleration Theory
O
tOt
tO
t
VVt
eV
etX
eVeV
VdtdV
log1
11
1
2
dtdV = tingkat perubahan kecepatan
, = konstan
1. Hitung HP yang dibutuhkan untuk mengatasi rolling, air dan grade resistance untuk suatu kendaraan dengan berat 3000 lbs dengan kecepatan 50 mph. Frontal area = 25 sq – ft, kemiringan jalan 1:50.
Type jalan adalah bituminuous concrete.Penyelesaian :
HP (rolling) = ..20550
47.1conbitRr
VWRr
58.3550
5047.12240300020
xxx
=
HP (air) =550
47.10017.0 2xVxAV
= 2.14550
5047.150250017.0 2
xxxx
HP (gradien) = %2550
47.15020 GxWxG
= 16.7550
47.15022403000220
xxxx
Total HP= 3.58 + 14.2 + 7.16 = 24.94
2. Suatu kendaraan bergerak dengan kecepatan 50 km/jam di belakang kendaraan lain, memutuskan untuk mendahului. Karakteristik percepatan dari kendaraan tersebut digambarkan sebagai :
sec
sec/015.022.1
t
mvVdtdv
3. Kendaraan bergerak dengan kecepatan 80 km/jam membutuhkan kurang dari 8.5 m untuk berhenti pada daerah tanjakan, kemudian bergerak turun pada kemiringan yang sama.Jika koef. Friksi = 0.55, tentukan :a. % gradienb. jarak pengereman pada turunan
(292km/hr) 81.33m/sec0.0151.22V
0.015V1.220dtdV
βt0 eβVα
dtdV m/sec89.13
36001000*5050km/jamVo
0βVαβVαlog
β1t
a.
b. Akselerasi maks jika speed=0
sec4.39km/hr/1.22m/sec0*0.0151.22
dtdV
c.
sec3.48km/hr/0.967m/sece13.89*0.0151.22dtdV 23*0.015
d. V=120km/hr=120/3.6=33.33m/sec