CE 370: Transportation Engineering Fundamentals

CE 370: Transportation Engineering Fundamentals ere are some equations that will be provided to you (if needed). Please note that you MUST know the definition of each term in the equations. I will NOT provide definitions along with the equations. Power Required to Overcome Aerodynamic Resistance 3 3 2 (horsepowers) 1100 a a R D f D R P C A V C AV hp     Coefficient of Rolling Resistance 0.01 1 ; when V is in ft./sect 147 0.01 1 ; when V is in m/sec 44.73 rl rl V f V f                 Power Required to Overcome Rolling Resistance ; (horsepower) 550 ; (N-m/sec) rl rl rl R R rl f WV hp P f WV   Maximum Tractive Effort     max max (for rear wheel drive) 1 (for front wheel drive) 1 f rl r rl W l f h L F h L W l f h L F h L           CE 370: Transportation Engineering Fundamentals Spring 2016 Engine Generated Power (Can be in Units of Horsepower or Metric System) 2 (in horsepower) 550 2 1000 e e e e e e M n hp M n P     Engine Generated Tractive Effort where is the overall gear reduction ratio is the mechanical efficiency of the drivetrain e d e d M F r      Relationship between Vehicle Spped and Engine Speed   0 2 1 is the slippage of teh drive axle (generally between 0.02 to 0.05 for passenger cars) e rn i V where i     Incorporating the Mass Factor into the Force Balance Equation 2 1.04 0.0025 0 m a rl g m F ma R R R          Geometric Design of Roadways 2 Braking Distance: 2 b v x a g G g         CE 370: Transportation Engineering Fundamentals Spring 2016 Vertical Curves     2 2 2 1 1 2 2 1 2 From Geometry: – if S < L ; (expressed in percent) 200 – if S > L 200 2 m m AS L A G G H H H H L S A        For Sag Vertical Curves Headlight Sight Distance If S < L   2 400 3.5 AS L S    If S > L 400 3.5  2 S L SA  For Sag Vertical Curves Underpass Sight DistanceIf S > L800 1 222cmH HHL SA    If S < L2800 1 22mcASLH HH   CE 370: Transportation Engineering Fundamentals Spring 2016Horizontal Curves2100vsVReg f    Degree of Curve5729.6; (Arc Definition)50; (Chord Definition)Sin2acRDRD    1tan21801 cos211cos2cos90v v svT RL RM RE RR R MSSDR                            Traffic Flow CharacteristicsGreenshield’s Model1f ju ku k ]]>