Assessment of pavement damage

Transcription

1 KTH AF293 Road Construction and Maintenance 19 March 213 Assessment of pavement damage or Quantitative measurement techniques Sigurdur Erlingsson 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 to pavement maintenance operations. 1

2 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 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

3 Visual survey cont. Inspection 1 Inspection 2 Inspection 3 Crack index, Si = 7 Crack index, Si = 46 Crack index, Si = LSprlåg, längd 2 m Krlåg, 6 m Krmedel, 8 m 2. LSprlåg, 1 m LSprsvår, 3 m Krlåg, 7 m 3. LSprmedel, 2 m LSprsvår, 3 m 4. TSprlåg, 1 st 5. LSprlåg, 2 m LSprmedel, 4 m 6. LSprlåg, 3 m Krlåg, 3 m 7. LSprlåg, 2 m LSprsvår, 4 m 8. LSprmedel, 3 m Krmedel, 6 m 9. TSprlåg, antal 1 st TSprmedel, 1 st 1. LSprmedel, 2 m Krmedel, 4 m Krsvår, 5 m Profile measurements - Rut 3

4 Höjd (mm) Profil (mm) Profile measurements cont Profillängd (mm) Profile measurements cont. Skandiahamnen Göteborg Västra stråket Tvärprofil Sektion (mm)

5 Slitage (mm) Wear due to studded tyres 1,5,5 1 1,5 2 2,5 3 3,5 4 4,5 -,5-1 -1,5-2 -2,5 Profil (mm) Coring and sampling 5

6 Coring and sampling Material testing Laboratory testing: IDT Test RLT test etc. Skid resistance 6

7 Friktion Skid resistance cont. 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 r 1 r 2 r 3 r 4 r 5 F D 2 D 3 D 4 D 5 D 1 D 7

8 Maximum deflection [μm] FWD - results Feb Mar Apr May Jun Jul Thaw reaching subbase 1 2 Thaw reaching subgrade 3 Completely thawed Base Course - Depth - 2 cm 1 E1 [MPa] 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

9 Norm. frequency [%] Lateral wandering (side position) l l A1 l r st. dev. =.245 m Control unit Charge amplifier 5 m 1 5-1, -,75 -,5 -,25,,25,5,75 1, Lateral Location [m] 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. 9

10 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). Continuous scanning 1

11 Road Surface Tester (RST) Road Surface Tester (RST) 11

12 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) SNRA s PMS data VÄGVERKET PMS , Road Surface Condition Hallands län, Väg: 6. Sträcka: 5, Körfält: 1, Riktning: Framåt, Sida för vägdata: 1 Vägversion: Vägbredd(m) Trafik(ÅDT) Tung traf(ådt) Bel.lager 1 1) 2) ABS115 Bel.lager 2 3).5.5 Bel.lager 3 4) 5) ABb115 1) ,2)ABS115,3) ,4) )ABb115, Spårdjup (mm) Ojämnhet IRI(mm/m) Best1 12

13 SNRA s PMS data VÄGVERKET PMS , Example Road Graph Dalarnas län, Väg: 6. Sträcka: 5-55, Körfält: 1, Riktning: Framåt, Sida för vägdata: 1 Vägversion: Trafik(ÅDT) Vägbredd(m) 13. Bel.lager 1 32HABS HABT1285 Bel.lager 2 MABT AG25844AG3284 Bel.lager 3 Y1B AG3284 Spårdjup (mm) Ojämnhet IRI(mm/m) Network level: Rut depth 13

14 Km Digital Images 2 m interval between the frames Total measured length (lane km) with RST Längd Km Längd Km År 14

15 Change in longitudinal unevenness Percentage IRI>4 mm/m AADT>2 vehicles/day Change in transverse unevenness Percentage Rut depth>15 mm AADT>2 vehicles/day 15

16 Frost depth penetration www3.vv.se/tjaldjup/ 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 16

17 Stress [kpa] Stress [kpa] Stress [kpa] strain, et [me] strain, et [me] Instrumentation - Response measurements 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 Time, t [ms] Time, t [ms] Instrumentation - stress measurements Base course Subbase Subgrade SPC69 SPC67 SPC65 FEM 3 25 SPCB SPC3 2 FEM 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] 17

18 Rut [mm] Crack index [-] IRI [-] The Swedish LTPP database Rv31 Nässjö - Mean 1. Rv 31 Nässjö AC BC, 8, Date 2 2, 15 Rv31 Nässjö - Crackindex, mean Sb 1 5 LTPP = Long Term Pavement Performance Sg 7, Depth [cm] Date Rv31 Nässjö - Mean Date 18