KTH AF293 Road Construction and Maintenance 1 April 214 Assessment of pavement damage or Quantitative measurement techniques Sigurdur Erlingsson sigurdur.erlingsson@vti.se VTI Linköping Why is it important to assess the condition of pavements? Pavement Management Systems (PMS) is a set of tools or methods to assist decision makers in finding a optimum strategies for providing, evaluating and maintaining pavement in a serviceable conditions over a period of time. PMS provides a rational and cost effective approach PMS provides a rational and cost-effective approach to pavement maintenance operations. 1
Methods Visual survey Profile measurements Wear due to studded tyres Coring and sampling Material testing Skid resistance Falling Weight Deflectometer (FWD) Lateral wander Roughness (smoothness) Continuous scanning Road Surface tester (RST) Roughness, Rut, Video profiling, Digital it images, etc. Pavement Instrumentation Temperature and moisture Frost penetration Response sensors Visual survey (inspection) Visual inspection includes: Cracking Longitudinal Fatigue cracking Single crack in the wheel path Alligator cracking Seasonal (frost heave) cracks Joint cracking Transversal (thermal) cracking Pattern cracks Block Cracking Joint Reflection Cracking Potholes Bleeding Ravelling Corrugation and shoving Segregation Patching Depressions 2
Visual survey cont. Inspection 1 Inspection 2 Inspection 3 Crack index, Si = 7 Crack index, Si = 46 Crack index, Si = 13 1. LSpr låg, längd 2 m Kr låg, 6m Kr medel, 8m 2. LSpr låg, 1 m LSpr svår, 3 m Kr låg, 7 m 3. LSpr medel, 2 m LSpr svår, 3 m 4. TSpr låg, 1 st 5. LSpr låg, 2 m LSpr medel, 4 m 6. LSpr låg, 3 m Kr låg, 3 m 7. LSpr låg, 2 m LSpr svår, 4 m 8. LSpr medel, 3 m Kr medel, 6 m 9. TSpr låg, antal 1 st TSpr medel, 1 st 1. LSpr medel, 2 m Kr medel, 4 m Kr svår, 5 m Profile measurements 3
Profile measurements cont. 5 1 2 3 4 Profil (mm) -5-1 -15 1996-1-21 1997-1-15 1998-11-17 1999-1-2 2-1-18 21-1-15 22-1-15 23-1-14 24-1-13 25-1-13 26-1-17-2 Profillängd (mm) Profile measurements cont. Skandiahamnen Göteborg Västra stråket Tvärprofil 5 Höjd (mm) 2 15 1 5-5 -1-15 -2-25 -3-35 -4-45 1 2 3 4 5 6 7 8 9 1 Sektion (mm) 11 12 13 14 5-12-13 6-12-1 7-11-11 4
Wear due to studded tyres 1,5,5 1 1,5 2 2,5 3 3,5 4 4,5 ge (mm) Slitag -,5-1 -1,5-2 -2,5 Profil (mm) Coring and sampling 5
Coring and sampling Material testing Laboratory testing: IDT Test RLT test etc. Skid resistance 6
Skid resistance cont. Friktion Skid resistance is the force developed when a tyre, that is prevented from rotating, slides along the pavement surface. Friction factor: f = F/L Skid number: SN = 1(f) where: F = frictional resistance to motion in plane of interface. L = load perpendicular to interface. 1,,9,8,7,6,5,4,3,2,1, 1 2 Sektion (m) Falling Weight Deflectometer (FWD) r r1 r2 r3 r4 r 5 F D2 D3 D4 D 5 D1 D 7
FWD - results D [µm] 15 3 45 1.jan 31.jan 2.mar 1.apr 1.maí 31.maí 3.jún 3.júl 29.ágú 8m 6m 2m m -2m -6m -8m 6 Base Course - Depth - 2 cm 1 E1 [MPa] 1 1 1 1.jan 31.jan 2.mar 1.apr 1.maí 31.maí 3.jún 3.júl 29.ágú Lateral wandering (side position) Passengers cars Heavy vehicles 8
Roughness (Smoothness) IRI = International Roughness Index Roughness is a measure of the texture of a surface. It is quantified by the vertical deviations of a real surface from its ideal form. If these deviations are large, the surface is rough; if they are small the surface is smooth. Roughness is typically considered to be the high frequency, short wavelength component of a measured surface. Profilometer is used to measure a surface's profile, in order to quantify its roughness. Vertical resolution is usually in the nanometre level, though lateral resolution is usually poorer. worldwide standard for measuring pavement smoothness called the International Roughness Index, or IRI. The index measures pavement roughness in terms of the number of mm per m (inches per mile) that a laser, mounted in a specialized van, jumps as it is driven across the road system. The lower the IRI number, the smoother the ride. A measure of a pavement's longitudinal surface profile as measured in the wheel path by a vehicle travelling at typical operating speeds. It is calculated as the ratio of the accumulated suspension motion to the distance travelled obtained from a mathematical model of a standard quarter car traversing a measured profile at a speed of 8 km/h (5 mph). The IRI is expressed in units of meters per kilometer (inches per mile) and is a representation of pavement roughness. Response Type Road Roughness Meters (RTRRMs) RTRRMs measure the vertical movements of an automobile or the axle of a trailer relative to the vehicle frame. The meters are installed in vehicles with a displacement transducer on the body located between the middle of the axle and the body of a passenger car or trailer. The transducer detects small increments of axle movement relative to the vehicle body. The output data consists of a strip chart plot of the actual axle body movement versus the time of travel. Roughness - IRI The international roughness index (IRI) was developed by the World Bank in the 198s. IRI is used to define a characteristic of the longitudinal profile of a travelled wheel-track and constitutes a standardized roughness measurement. The commonly recommended units are meters per kilometer (m/km) or millimeters per meter (mm/m). 9
Continuous scanning Road Surface Tester (RST) 1
Road Surface Tester (RST) RST - what is measured Three longitudinal profiles (.1 meter) Transverse profile (1 meter) Rut depth, max, left and right (2 meter) IRI, left and right (2 meter) Macrotexture, MPD in three tracks (1 meter) Megatexture, two tracks (1 meter) Curvature, Hilliness (2 meter), Crossfall (1 meter) Digital images (2 meter) 11
SNRA s PMS data VÄGVERKET PMS 291125, 15.37 6. 2. Road Surface Condition Hallands län, Väg: 6. Sträcka: - 5, Körfält: 1, Riktning: Framåt, Sida för vägdata: 1 Vägversion: 29923 1 2 3 4 5 Vägbredd(m) 11.3 Trafik(ÅDT) 9393 55 9591 Tung traf(ådt) 1725 9 1738 Bel.lager 1 1) 2) ABS115 Bel.lager 2 3).5.5 Bel.lager 3 4) 5) ABb115 1)43.47824967,2)ABS115,3)34.782592773,4)39.1341611 5)ABb115, Spårdjup (mm) 5 1 15 2 Ojämnhet IRI(mm/m) 6 5 4 3 2 1 1999-4-22 2-5-22 21-5-8 22-5-8 23-5-1 24-5-7 26-5-29 27-6-25 28-5-12 29-5-6 Best1 SNRA s PMS data VÄGVERKET PMS 1998122, 17.58 Example Road Graph Dalarnas län, Väg: 6. Sträcka: 5-55, Körfält: 1, Riktning: Framåt, Sida för vägdata: 1 648. 646. Vägversion: 97727 5 51 52 53 54 55 Trafik(ÅDT) 445 64 Vägbredd(m) 13. Bel.lager 1 32HABS1294 32HABT1285 Bel.lager 2 MABT1694 44AG25844AG3284 Bel.lager 3 Y1B1683 44AG3284 Spårdjup (mm) 5 1 15 2 Ojämnhet 6 IRI(mm/m) 5 4 3 2 1 9361 9453 94912 9567 9669 9765 12
Network level: Rut depth Digital Images 2 m interval between the frames 13
Total measured length (lane km) with RST Längd Km 9 8 7 6 5 Km 4 Längd Km 3 2 1 1998 1999 2 21 22 23 24 25 26 27 28 År Change in longitudinal unevenness Percentage IRI>4 mm/m AADT>2 vehicles/day 14
Change in transverse unevenness Percentage Rut depth>15 mm AADT>2 vehicles/day Frost depth penetration www3.vv.se/tjaldjup/ 15
Instrumented test roads - APT testing The HVS Nordic is a mobile APT test facility. Technical Specifications Test wheel: Dual or single wheel Load range: 3 11 kn Capacity: 15 passages/week Loading direction: single or bi-directional Max speed: 12 km/h Lateral wander:.7 m Pavement temp: 3 C Power: Diesel or electricity APT = Accelerated Pavement Testing HVS = Heavy Vehicle Simulator Instrumentation - Response measurements. 4.8 1.1 2.9 35.1 Asphalt Concrete Bituminous Base Granular Base Course Granular Subbase Subgrade, sand Instrumentation Pressure cell Horizontal strain, longitudinal Horizontal strain, transversal Vertical strain Depth [cm] Vertical deflection 8 6 ASG 17 - X ASG 18 - Y 8 6 ASG 17 - X ASG 18 - Y strain, t [ ] 4 2 strain, t [ ] 4 2-2 5 1 15 2 Time, t [ms] -2 5 1 15 2 Time, t [ms] 16
Instrumentation - stress measurements Stress [kpa] 7 6 5 4 3 2 1 Base course Subbase Subgrade 3 SPC69 25 SPCB SPC67 SPC65 FEM Stress [kpa] SPC3 2 FEM 15 1 5 Stress [kpa] 1 8 6 4 2 SPC27 FEM 1,9 2, 2,1 2,2 2,3 Time [sec] 1,4 1,5 1,6 1,7 1,8 1,9 2, Time [sec] 1,4 1,5 1,6 1,7 1,8 1,9 2, Time [sec] The Swedish LTPP database 2. 1.5 Rv31 Nässjö - Mean IRI [-] 1. Rv 31 Nässjö 5.5 AC BC, 8,5. 1988 199 1992 1994 1996 1998 2 22 24 26 28 Date 2 Sb 2, Crack index [-] 15 1 5 Rv31 Nässjö - Crackindex, mean LTPP = Long Term Pavement Performance Sg 7, Depth [cm] Rut [mm] 1988 199 1992 1994 1996 1998 2 22 24 26 28 Date 16 14 12 Rv31 Nässjö - Mean 1 8 6 4 2 1988 199 1992 1994 1996 1998 2 22 24 26 28 Date 17