Presentation on theme: "By Mr.Surasak Kaewdee Transportation Engineering Dr. Kunnawee Kanitpong (Adviser) Asian Institute of Technology ANALYSIS OF TRAFFIC LOADING CHARACTERISTICS."— Presentation transcript:
By Mr.Surasak Kaewdee Transportation Engineering Dr. Kunnawee Kanitpong (Adviser) Asian Institute of Technology ANALYSIS OF TRAFFIC LOADING CHARACTERISTICS FOR MECHANISTIC-EMPIRICAL PAVEMENT DESIGN IN THAILAND
Introduction Method for the flexible pavement design 1.Empirical Method - based on past experience designs and the data generated from the field tests 2.Mechanistic – Empirical (M-E) Method - based on the use of stress, strain and deflection analysis to determine the minimum thickness of pavement
Introduction Disadvantage of the empirical design method. 1.Limited only to certain pavement materials that were developed Limited only one or two pattern. 2.The thickness design of the pavement structure using design charts will have some errors. Advantage of the M-E design method 1.The design is correct and confident anywhere and any environment condition. 2.Pavements can be designed according to any available materials. 3.The approach can provide any magnitude of wheel loads and frequencies. 4.Pavement can be designed into various patterns.
Limited Traffic Applications AXLE LOAD REPETITIONS PAVEMENT THICKNESS CurrentDesigns Projection A > 100 Million Projection B Projection C Projection B Data Limits (AASHO Road Test) Source: FHWA (2002)
Problem statement Problem load characterization in Thailand. 1.The count station counts only the number of each vehicle. 2.The Truck factors are always assumed for the new pavement design and the rehabilitated design. 3.The calculation of ESALs does not represent the existing types and categories of vehicles. 4.The new limits of axle load and gross weight for ten wheels standard trucks has been increased from 21 tons to 25 tons.
Objectives of Study To classify loading types and configuration for the design. To analyze the input data as collected from weigh- in-motion (WIM) for the M-E design method. To use the M-E design method by considering the current traffic load in Thailand. To develop the guidelines of traffic data collection by using WIM for future use in the design and maintenance of pavements in Thailand.
Methodology Study Framework Conclusions and Recommendation Collect Traffic Data from WIM Station and Weight control center Identify and Understand Load configuration for use in M-E design and maintenance Identify and Understand Load configuration for use in M-E design and maintenance Classify groups of vehicles Test Location Traffic Data Analysis Truck Factor and ESAL Design and Compare pavement structure by using obtainable load parameter in M-E pavement design method Determine and Compare thickness of pavement overlay by M-E method and FWD Traffic Loads
Methodology Test Location Sikiu (Outbound) WIM Station Tatamnuk (Inbound) WIM Station Suwintawong (Inbound) WIM Station Bang pai (Inbound) WIM Station
Methodology Weigh-in-motion The devices which measure truck weights and axle configuration at highway speeds, are an integral part of the program to provide highway-use data.
Collection traffic data from two locations WIM stations Weight Control Center in DOH
Methodology Observe from January 2008 to December Collect in one direction located at the four selected WIM stations. Classify into 13 standard vehicle classes Select monthly reports; class by hour, class by single axle weight, class by tandem axle weight and class by tridem axle weight. Provide a load interval of each axle group in 2 tons. Assumption of Data Collection
Methodology Load Characterization Equivalent Axle Load Factor (EALF) Defines the damage per pass to a pavement by axle in question relative to the damage per pass of a standard axle load (18-kip, 80-Kn) single-axle load The failure criterion for fatigue cracking Truck factor Equivalent Single Axle Load(ESAL) The total number of passes of the standard axle load during the design period The sum of ESALs for all trucks weighed divided by the number of trucks Traffic Analysis
Comparison of Vehicle Classification in two station types Count StationsWIM Stations No.NameImageClassNameImage 1BI+TRI CYCLE 2MOTORCYCLE 1Motorcycle 3CAR < = 7 P 2Passenger Cars 4CAR > 7 5LIGHT BUS 4Buses 6MEDIUM BUS 7HEAVY BUS 8 LIGHT TRUCK (Light Truck or Pick-Up) 3 Single Unit Truck (Two Axle, Four Tire) 9 MEDIUM TRUCK (Two-Axle Truck (6 Wheels)) 5 Single Unit Truck (Two Axle, Six Tire) 10 HEAVY TRUCK (Three-Axle Truck,10 Wheels) 6 Single Unit Truck (Three Axle) 7 Single Unit Truck (Four Axle) 11 SEMI TRAILER Semi Trailer (Four or More Axle) 8 Single Trailer (Three Axle) Single Trailer (Four Axle) 9 Single Trailer (Five Axle) 10 Single Trailer (Six or More Axle) 12 FULL TRAILER Full trailer (Four or More Axle) 11 Full Trailer (Five Axle) 12 Full Trailer (Six Axle) 13 Multi-Trailer (Seven or More Axle)
Traffic Data Result and Analysis Truck Monthly Distributions Truck Traffic Distribution Highway number WIM Station Sikiu (Outbound) TatamnakSuwintawongBang pai Data Collection (month) Time periodPercent of daily truck traffic,% midnight to 6 a.m a.m a.m a.m. - 4 p.m p.m. - 8 p.m p.m. - midnight Truck Hourly Distributions Normalized truck traffic distribution
Traffic Data Result and Analysis AADT from four WIM stations Average Annual Daily Traffic (AADT) AADT on highway number 304 from the permanent count station. Class of Veh. Highway road number WIM Station Sikiu (Outbou nd) Tata mnak Suwint awong Bang pai Description Average Annual Daily Traffic (AADT) 1Motorcycle1, Passenger car2,96426,8785,54114,255 4Bus Single Unit truck 3 Two Axle, Four Tire174893,0381,485 5 Two Axle, Six Tire Three Axle Four Axle2412 Single Trailer 8 Three and Four Axle Five Axle Six or More Axle Full Trailer 11 Five Axle Six Axle Multi Trailer 13 Seven or More Axle Summary5,37828,9009,91118,190 Both directions10,75657,80019,82236,380 Year Types of vehicles TOTAL (AADT) CAR< =7P CAR>7 P LBMBHBLTMTHT FULL _TL SEMI _TL ,7574, , ,2381,2351,047 29,169 total car17,184 MB+ HB777 MT+ HT4,845 FTL+ STL2, ,6795, , ,1811,5221,080 29,066 total car16,198 MB+ HB659 MT+ HT5,100 FTL+ STL2, ,5325, , , ,177 total car20,483 MB+ HB804 MT+ HT4,064 FTL+ STL1,623
Traffic Data Result and Analysis Truck Factor Highway Road number WIM Station Sikiu (Outbound) TatamnakSuwintawongBang pai Data Collection (month) Bus Single Unit truck Two Axle, Four Tire Two Axle, Six Tire Three Axle Four Axle All Single Unit truck Single Trailer Three and Four Axle Five Axle Six or More Axle All Single Trailer Full Trailer Five Axle Six Axle All Full Trailer Multi Trailer Seven or More Axle All Truck
Traffic Data Result and Analysis Equivalent Single Axle Load (ESAL) Highways number24304 WIM StationSikiu (Outbound)TatamnakSuwintawongBang pai Vehicle class\ Purpose of design New design Overlay pavemen t New design Overlay pavemen t New design Overlay pavement New design Overlay pavemen t Bus451,283178,07931,06312,2581,257,277496,1282,163,153853,592 Single Unit truck Two Axle, Four Tire9,315,766 3,676,05 1 1,025, , ,272, ,503, ,232,83 7 6,010,96 0 Two Axle, Six Tire1,621,052639,676278,402109,8591,678,906662,5051,667,788658,118 Three Axle3,188,659 1,258,26 2 2,064, ,4801,134,754447,7801,688,090666,130 Four Axle41,17916,2506,8532,7044,3101,70111,2414,436 Single Trailer Three and Four Axle620,050244,67591,12935,960259,857102,541409,384161,545 Five Axle2,910,304 1,148,42 2 1,284, ,0031,161,966458,5181,785,481704,560 Six or More Axle2,334,745921,303 2,068, ,370360,825142,383594,124234,444 Full Trailer Five Axle4,159,379 1,641, ,775292,314843,593332,8862,669,148 1,053,26 0 Six Axle1,150,497453,992300,623118,627296,830117,1311,152,176454,655 Multi Trailer Seven or More Axle572,606225,953268,020105,76217,7046,98662,73224,755 ESAL Design Traffic 16,478,45 0 6,502,48 5 5,099,85 8 2,012, ,959,326 68,645, ,692,53 9 9,743,81 0 ESAL for new design and rehabilitation of four highways from WIM database
Pavement Design and Analysis New Pavement Design Typical Cross Section of the selected highway number 304 NoLayer Relations between thickness of pavement structure (cm.) and materials of each layer. For ESAL=2.47E+7 (WIM station) The first pavement structure The second pavement structure The third pavement structure The fourth pavement structure 1Pavement Asphalt Concrete 20 Asphalt Concrete 15PMA10PMA5 2BaseSoil Cement20 Modified Crush Rock 20Soil Cement20 Modified Crush Rock 30 3Subbase Soil Aggregate 20 Soil Aggregate 20 Soil Aggregate 20 Soil Aggregate 20 4 Selected Material Selected Material "A" 15 Selected Material "A" 30 Selected Material "A" 20 Selected Material "A" 40 5Subgrade(CBR=4%)infinite(CBR=4%)infinite(CBR=4%)infinite(CBR=4%)infinite Thickness of various new designs
Pavement Design and Analysis New Pavement Design Relation between the various pavement structures and allowable ESAL application sensitivity of structural responses
Overlay by Falling Weight Deflectometer (FWD) procedure Evaluate the physical properties of a pavement. Determine the requested thickness of the pavement overlay. LayerMaterial Type Thickness (cm) Elastic Modulus (Mpa) 1 Existing Asphalt Concrete 101,961 2Soil Cement Base Soil Aggregate Subbase and Selected Material “A” Subgrade (CBR=4%) infinite239 Source of Traffic data Year Average Overlay (cm.) Standard deviation Overlay (cm.) Overlay (cm.) Count station at Km Bang pai WIM station at Km Pavement Rehabilitation (Overlay) Pavement Design and Analysis Overlay by M-E method The thickness of the pavement overlay on this section of highway number 304 is two centimeters.
The traffic data from the WIM stations are accurate and reliable than the count station. The annual truck factors represent the actual truck distributions relating to the current traffic volume. The ESAL are determined for each vehicle which is more accurate and reliable. Truck distributions are important issues for planning and geometrical purposes. The new design by M-E method can design various pavement structures. The thickness of overlay design is two centimeters for both FWD and M-E approaches. Conclusions Conclusions and Recommendations Recommendations The WIM systems should be calibrated periodically. A future study should test the material properties.. Development of traffic data collection and results by using WIM for future use in the new design and maintenance of pavements in Thailand. These traffic data are collected continuously and systematically.