10-Traffic Characterization ( Highway Engineering Dr. Sherif El-Badawy )
•
4 likes•1,249 views
10 traffic-characterization ( Highway Engineering Dr. Sherif El-Badawy )
Recommended
More Related Content
What's hot
What's hot (20)
Viewers also liked
Viewers also liked (20)
Similar to 10-Traffic Characterization ( Highway Engineering Dr. Sherif El-Badawy )
Similar to 10-Traffic Characterization ( Highway Engineering Dr. Sherif El-Badawy ) (20)
More from Hossam Shafiq I
More from Hossam Shafiq I (20)
Recently uploaded
Recently uploaded (20)
10-Traffic Characterization ( Highway Engineering Dr. Sherif El-Badawy )
- 1. 1 Mansoura University - Faculty of Engineering – Public Works Engineering Dept. 1 Traffic Characterization Mansoura University - Faculty of Engineering – Public Works Engineering Dept. 2 Traffic Loading • Primary input to any design procedure • Issues: • Vehicle Characteristics • Weight • Wheel and axle configuration • Frequency of occurrence • Traffic Volume • Current • Future (traffic growth) • Other • Lateral wander • Often not well-defined in practice Mansoura University - Faculty of Engineering – Public Works Engineering Dept. Traffic Loads Characterization Pavement Thickness Design Are Developed To Account For The Entire Spectrum Of Traffic Loads Cars Pickups Buses Trucks Trailers Mansoura University - Faculty of Engineering – Public Works Engineering Dept. Critical Response Values et ec et ec et at surface + bottom of all bound layers (cracking) ec at midthickness of all layers + top of subgrade (rutting)
- 2. 2 Mansoura University - Faculty of Engineering – Public Works Engineering Dept. 6 Traffic Composition Mansoura University - Faculty of Engineering – Public Works Engineering Dept. 7 Axle Configuration Single Axle Single Tires Single Axle Dual Tires Tandem Axle Dual Tires Tridem Axle Dual Tires Mansoura University - Faculty of Engineering – Public Works Engineering Dept. 8 Axle Configuration
- 3. 3 Mansoura University - Faculty of Engineering – Public Works Engineering Dept. Axle Configuration Parameters Axle Width Axle Spacing Tire Pressure Dual Tire Spacing Wheel Base Mansoura University - Faculty of Engineering – Public Works Engineering Dept. FHWA Vehicle Classes 1 2 3 4 5 6 7 8 9 10 11 12 13 Mansoura University - Faculty of Engineering – Public Works Engineering Dept. Normalized Truck Distribution by Truck Class El-Badawy, et al. TRB, 2012 Mansoura University - Faculty of Engineering – Public Works Engineering Dept. Sources of Traffic Data • Weigh-in-motion (WIM) • Automatic vehicle classification (AVC) • Traffic counts
- 4. 4 Mansoura University - Faculty of Engineering – Public Works Engineering Dept. Highway Graduation Project 2011 Mansoura University - Faculty of Engineering – Public Works Engineering Dept. 15 Design Approaches •Fixed Traffic •Fixed Vehicle •Variable Traffic and Vehicle Mansoura University - Faculty of Engineering – Public Works Engineering Dept. 16 Fixed Traffic • Thickness design governed by single wheel load • Multiple wheels converted to equivalent single wheel load (ESWL) • Number of traffic repetitions is not a variable • Historical usage: • Airport pavements • Highway pavements w/ heavy wheel loads but light traffic volume • Method rarely used today Mansoura University - Faculty of Engineering – Public Works Engineering Dept. 18 Important Definitions • Standard Axle Load (SAL): A single axle with dual tires that has a weight of 18,000 lb (80 KN). • ESAL: The number of repetitions of an 18,000 lb single axle load
- 5. 5 Mansoura University - Faculty of Engineering – Public Works Engineering Dept. 19 Equivalent Single Axle Load (ESAL) • Most common standard load • Developed at the AASHO Road Test • Load equivalency factors (LEFs) • The number of ESALs needed to cause the same damage as the load in question 1 ESAL = damage caused by one 18,000 lb single axle load Mansoura University - Faculty of Engineering – Public Works Engineering Dept. Load Equivalency Factors (LEF) LEFs Can Be Based On: • Equivalent Stress or Strain at a Given Location (Mechanistic) • Equivalent Deflection at a Given Location (Mechanistic) • Equivalent Serviceability Loss (AASHTO) Mansoura University - Faculty of Engineering – Public Works Engineering Dept. LEF = EALF • Ratio of damage caused by a certain axle to that caused by the standard one. • Based on Fatigue, • LEF ≈ {Wi / Ws}4, where W = weight of axle • Based on AASHTO Equation: • For Flexible Pavements • For Rigid Pavements Mansoura University - Faculty of Engineering – Public Works Engineering Dept. AASHTO Load Equivalency Factors Load Equivalency Factor (LEF): No. of repetitions of 18-k SAL Load causing given PSI No. of repetitions of X- k Y-Axle Load for a same PSI Change for each: Pavement Type Thickness Terminal Serviceability.
- 6. 6 Mansoura University - Faculty of Engineering – Public Works Engineering Dept. ESALF • Ratio of damage caused by a certain axle to that caused by the standard one. • Based on Fatigue, • ESALF ≈ {Wi / Ws}4, where W = weight of axle • Based on AASHTO Eqn, • For Flexible Pavements, see Equation in Next Slide Mansoura University - Faculty of Engineering – Public Works Engineering Dept. AASHTO 1993 Equation for LEF for Flexible Pavement Wtx = number of applications of given axle Wt18 = number of standard axle passes (18-kips single axle) Lx = load of axle group being evaluated, kips L2 = axle code (1 for single, 2 for tandem, and 3 for tridem, 4 for quad) b18 = value of bx when Lx = 18 and L2 = 1 pt = terminal serviceability index SN = structural number LEF = load equivalency factor tx t18 W W LEF 18 t x t 22x t18 tx β G β G )4.33log(L)L4.79log(L1)4.79log(18 W W log 1.54.2 p4.2 logG t t 3.23 2 5.19 3.23 2x x L1SN )L0.08(L 0.40β Where: ESALs 12,000 lbs LEF = 0.189 28,000 lbs LEF = 0.495 28,000 lbs LEF = 0.495 Mansoura University - Faculty of Engineering – Public Works Engineering Dept. (Huang, 2004) Mansoura University - Faculty of Engineering – Public Works Engineering Dept. للطرق المصري للكود طبقا بها المسموح والحموالت المحاور أوزان
- 7. 7 Mansoura University - Faculty of Engineering – Public Works Engineering Dept. للطرق المصري للكود طبقا بها المسموح والحموالت المحاور أوزان Mansoura University - Faculty of Engineering – Public Works Engineering Dept. Mansoura University - Faculty of Engineering – Public Works Engineering Dept. Approximate Relations to Compute LEF Mansoura University - Faculty of Engineering – Public Works Engineering Dept. REGULAR MIXED TRAFFIC Equivalent Number of 18k Single Axle Loads
- 8. 8 Mansoura University - Faculty of Engineering – Public Works Engineering Dept. 31 Truck Factor = S (Number of axles * LEF)/number of vehicles Truck Factor = S LEF = 0.189 + 0.495*2 = 1.368 ESALs 12,000 lbs LEF = 0.189 28,000 lbs LEF = 0.495 28,000 lbs LEF = 0.495 Truck Factors Truck Factor (TF) = sum of all LEFs for each truck Mansoura University - Faculty of Engineering – Public Works Engineering Dept. TF = 1.5 to 2.5 According to Egyptian Code 32 Truck Factor Mansoura University - Faculty of Engineering – Public Works Engineering Dept. Truck Factors – Urban Vehicle Type Interstate Freeways Other Principal Minor Arterials Collectors Single-unit trucks 2-axle, 4-tire 0.002 0.015 0.002 0.006 - 2-axle, 6-tire 0.17 0.13 0.24 0.23 0.13 3-axle or more 0.61 0.74 1.02 0.76 0.72 All single units 0.05 0.06 0.09 0.04 0.16 Tractor semi- trailers 4-axle or less 0.98 0.48 0.71 0.46 0.40 5-axle 1.07 1.17 0.97 0.77 0.63 6-axle or more 1.05 1.19 0.90 0.64 - All multiple units 1.05 0.96 0.91 0.67 0.53 ALL TRUCKS 0.39 0.23 0.21 0.07 0.24 From MS-1, Table IV-5 Mansoura University - Faculty of Engineering – Public Works Engineering Dept. 34 Truck Factors – Rural Vehicle Type Interstate Other Principal Minor Arterials Major Collector Minor Collector Single-unit trucks 2-axle, 4-tire 0.003 0.003 0.003 0.017 0.003 2-axle, 6-tire 0.21 0.25 0.28 0.41 0.19 3-axle or more 0.61 0.86 1.06 1.25 0.45 All single units 0.06 0.08 0.08 0.12 0.03 Tractor semi-trailers 4-axle or less 0.62 0.92 0.62 0.37 0.91 5-axle 1.09 1.25 1.05 1.67 1.11 6-axle or more 1.23 1.54 1.04 2.21 1.35 All multiple units 1.04 1.21 0.97 1.52 1.08 ALL TRUCKS 0.52 0.38 0.21 0.30 0.12 From MS-1, Table IV-5
- 9. 9 Mansoura University - Faculty of Engineering – Public Works Engineering Dept. Truck Distribution - Rural Vehicle Type Interstate Other Principal Minor Arterials Major Collector Minor Collector Single-unit trucks 2-axle, 4-tire 43 60 71 73 80 2-axle, 6-tire 8 10 11 10 10 3-axle or more 2 3 4 4 2 All single units 53 73 86 87 92 Tractor semi-trailers 4-axle or less 5 3 3 2 2 5-axle 41 23 11 10 6 6-axle or more 1 1 <1 1 <1 All multiple units 47 27 14 13 8 ALL TRUCKS 100 100 100 100 100 From MS-1, Table IV-1 Mansoura University - Faculty of Engineering – Public Works Engineering Dept. 36 Truck Distribution – Urban Vehicle Type Interstate Other Principal Minor Arterials Major Collector Minor Collector Single-unit trucks 2-axle, 4-tire 52 68 67 84 86 2-axle, 6-tire 12 12 15 9 11 3-axle or more 2 4 3 2 <1 All single units 66 82 85 95 97 Tractor semi-trailers 4-axle or less 5 5 3 2 1 5-axle 28 13 12 3 2 6-axle or more 1 <1 <1 <1 <1 All multiple units 34 18 15 5 3 ALL TRUCKS 100 100 100 100 100 From MS-1, Table IV-1 Mansoura University - Faculty of Engineering – Public Works Engineering Dept. Mansoura University - Faculty of Engineering – Public Works Engineering Dept. 38 Traffic Analysis ESAL = Equivalent 18,000 lb single axle load AADTi = First year annual average daily traffic for axle i in both directions Gjt = growth factor for growth rate j and design period t fd = lane distribution factor df = directional distribution factor Ni = Number of axles FEi = Load equivalency factor for axle i Ti = Truck Factor ESAL = 365(fd)(df)(Gjt)S(AADTi)(Ni)(FEi) using LEF ESAL = 365(fd)(df)(Gjt)S(AADTi)(Ti) using Truck Factor
- 10. 10 Mansoura University - Faculty of Engineering – Public Works Engineering Dept. Percentage of truck traffic traveling in one direction 47% 53% Directional Distribution Mansoura University - Faculty of Engineering – Public Works Engineering Dept. ADT 20,000 25% trucks 75% trucks ADT 60,000 8% trucks 39% trucks 53% trucks Design for worst case!! Lane Distribution Mansoura University - Faculty of Engineering – Public Works Engineering Dept. Lane Distribution Factor N o. of Traffic Lanes in each Direction % Trucks in Design Lane 1 100 2 80–100 3 60–80 4 or more 50–75 Mansoura University - Faculty of Engineering – Public Works Engineering Dept. 42 Direction and Lane Factors (dfXfd) Number of Traffic Lanes (Two Directions) % Trucks in design lane 2 50 4 45 6 or more 40
- 11. 11 Mansoura University - Faculty of Engineering – Public Works Engineering Dept. 43 Growth Factor (G) (Huang, 1993) Based on standard compound growth equations. r r G n 11 r = growth rate n = Design period, years For annual growth rate (r=0), G = n r = 2 -7 % Egyptian Code Mansoura University - Faculty of Engineering – Public Works Engineering Dept. Example of Single Axle Growth 0 100000 200000 300000 400000 2000 2010 2020 2030 2040 Year Projectednumberof singleaxles Mansoura University - Faculty of Engineering – Public Works Engineering Dept. Example 1 - Calculation of ESALS Axle Load, kips # of Axles per 1000 trucks Single Axles 2 753 4 299 6 105 8 34 10 42 12 30 14 41 16 93 18 110 20 80 22 50 24 11 Axle Load, kips # of Axles per 1000 trucks Tandem Axles 14 1 16 5 18 15 20 20 22 36 24 42 26 84 28 92 30 50 32 12 34 8 36 4 38 2 40 1 42 1 Mansoura University - Faculty of Engineering – Public Works Engineering Dept.
- 12. 12 Mansoura University - Faculty of Engineering – Public Works Engineering Dept. Axle Load Spectra 0% 2% 4% 6% 8% 10% 12% 14% 16% 18% 0 10000 20000 30000 40000 50000 60000 70000 80000 90000 PercentAxles Axle Load, lb 000169-South,VC 9, Tandem Axles January February March April May June July August September October November December El-Badawy, et al. TRB, 2012