Word count: 248 words (Abstract) + 3,821 words (Text) words (References) + 12 tables/figures x 250 words (each) = 7,267 words

Transcription

1 TUNNEL LINING DAMAGE ASSESSMENT USING MOBILE LASER SCANNING PITTSBURGH, PA IMPLEMENTATION PHASE OF FHWA SHRP-R0G Kaz Tabrizi, PhD, PE Vice President Advanced Infrastructure Design Crossroads Drive, Hamilton, NJ 0- Tel: ktabrizi@aidpe.com Manuel Celaya, PhD Project Manager Advanced Infrastructure Design Crossroads Drive, Hamilton, NJ 0- Tel: mcelaya@aidpe.com Bradley S. Miller, PE, CBSI Chief Structural Engineer - Inspections Mackin Engineering Company RIDC Park West, Industry Drive, Pittsburgh, PA Tel: bmiller@mackinengineering.com Andreas Wittwer, PhD SPACETEC Datengewinnung GmbH Salzstraße D-0 Freiburg Tel: 00//-0 andreas.wittwer@spacetec.de Louis Ruzzi, PE District Bridge Engineer PennDOT District -0 Tel: LRUZZI@pa.gov Word count: words (Abstract) +, words (Text) + words (References) + tables/figures x 0 words (each) =, words Submission Date 0/0/0 Revised Paper Submission Date //0

2 Tabrizi, Celaya, Miller, Wittwer and Ruzzi ABSTRACT This paper presents the results of a nondestructive (NDT) laser scanner investigation that was conducted in one night using the Spacetec TS laser scanner in one tube in each of the Liberty and Armstrong tunnels in Pittsburgh, PA. A Portable Seismic Property Analyzer (PSPA), a handheld NDT ultrasonic seismic device, was used to investigate a 00 long segment of the lining of the Liberty tunnel, for which the results are also presented. The investigation was complemented with a limited inspection with traditional techniques (hammer sounding, coring, etc.) to validate NDT findings. The above work was funded by the FHWA under the auspices of Round of the Implementation Assistance Program (IAP) of SHRP R0G. Both technologies incorporated in this study were also used and reviewed in the original SHRP R0G project. Using the above scanner and the supporting suite of software, high resolution imagery, thermal imagery and -D profiles were obtained for the full length of the tunnels. The deliverables included complete mapping and inventory of distresses and moisture intrusion behind the lining. On the Armstrong Tunnel, Spacetec technology was successful at detecting cold anomalies (tile debonding, water intrusion, etc.). However, on the Liberty Tunnel, detecting debonding/delamination was less effective due to insufficient temperature gradient at the time of scanning within this particular tunnel. PSPA results correlated well against results obtained from traditional techniques. Areas with lower seismic modulus correlated well with areas showing debonding or delamination. Areas of severe debonding were also clearly identified with the PSPA. Keywords: Tunnel lining, Mobile laser scanning, High-resolution imagery, Thermal imagery, Profile, PSPA, Nondestructive Testing, Asset Management

3 Tabrizi, Celaya, Miller, Wittwer and Ruzzi INTRODUCTION Roadway tunnels are critical infrastructure assets as they normally carry heavy traffic and are exposed to aggressive conditions. As a result, inspection of tunnels normally creates logistical problems for the tunnel owners especially as traffic needs to be detoured, sometimes for long distances. In order to keep the traffic interruptions to a minimum, tunnel owners prefer that inspections are performed quickly and comprehensively. The concept of get in, get out and stay out is especially applicable to tunnels. To find effective solutions, TRB s SHRP R0G project initiated a study of all available technologies used for mapping of distresses within or behind concrete lining of tunnels. Technologies ranged from mobile to discrete point by point testing devices (). In this report, the Spacetec TS laser scanner, which was used in Virginia s Chesapeake Bay Bridge Tunnel, was referred to as a mature scanning technology. Since then, the FHWA entered into the implementation phase of the R0G, which is designed to take the concepts developed in the original SHRP effort and put them into practice under the auspices of the Implementation Assistance Program (IAP). Under Round of the IAP, two () such studies were awarded. Our paper presents the results of the scanning of the Armstrong and Liberty tunnels in Pittsburgh, PA for PennDOT. Advaned Infrastructure Design, the American partner to Spacetec, performed this work for Mackin Engineering, who directly contracted with PennDOT. This paper summarizes the results of Spacetec s TS mobile laser scanning followed by limited verification testing using the PSPA on a selected area in one of the tunnels. As a networklevel scanning tool, the Spacetec system records three () types of data: visual, thermal and the profile of the entire tunnel via its rotating laser scanner. The high resolution imagery allows the user to see and consequently map (by way of tracing) any and all distresses that exist on the face of the tunnel lining. The thermal feature of the system records the surface temperature profile of the tunnel with a resolution of 0.-degree C or 0.-degree F. As a result, the user can clearly detect anomalies such as areas of moisture intrusion. Subsurface features such as voids or debonding can also be detected, if a temperature gradient exists between the rock and the tunnel air at the time of scanning. Using a combination of laser imagery and thermal imaging, deficiencies such as concrete spalling, efflorescence, cracks, tile damage, and water infiltration can be detected and mapped on the tunnel lining. When a distress or anomaly is mapped, its size, location, and nature (cold or warm anomalies indicating the type of damage) are recorded in the system. Locations are normally tied to the base mapping reference system, indicating precise locations of the observed features on the lining. All geo-located features populate the database within the software, allowing specific reports to be obtained. Examples are provided later in this paper. The objective of the PSPA testing was to evaluate the integrity and to identify areas of debonding/delamination of the concrete lining within a limited section of the Liberty Tunnel. The PSPA determines the variation in dynamic/seismic modulus with depth of the exposed layer in the field. In general, larger seismic modulus corresponds to higher concrete strength. The PSPA is also capable of conducting Impact Echo (IE) tests simultaneously and measuring the resonant frequency of the tested area. IE has proven to be effective in detecting discontinuities in concrete such as delaminations, voids, cracks, and debonding (,, and ). In this paper, the selected NDT methods used in this study are briefly overviewed. The description of the tunnels investigated is presented next, followed by the results obtained. Finally, summary and conclusions of this study are presented.

4 Tabrizi, Celaya, Miller, Wittwer and Ruzzi 0 NDT TECHNOLOGIES USED IN THIS STUDY For the sake of brevity, a summary of technologies used in this study are presented next. Spacetec Laser Scanning Technology Via its three () channels, the Spacetec tunnel scanner combines visual, -D profile and thermographic data in a single measurement process. Hence the scanner captures not only the position and grey value of laser data but also the surface temperature of each of the measured survey points. (). Information in those three channels is collected simultaneously using the same scan mirror, rotating at frequencies up to 00 Hz. The scanner has a 0 field of view and thus provides surface data in one single run. The angular resolution of 0000 pixels per 0 results in a high point density on the tunnel surface (typically mm). The scanning is performed nondestructively at speeds of about. mph, therefore minimizing traffic disruption (Figure ) when compared with other methods. 0 0 FIGURE TS Scanner detail and scanner mounted on a testing vehicle. The data obtained provides detailed information about the tunnel geometry and its surface conditions. As a result, all defects (such as cracks, spalls, etc.) and other anomalies (such as moisture intrusion and debonding) are geo-located. Therefore, it is useful system at both the network-level and the project-level, making it a candidate for reconnaissance prior to mobilization for regular maintenance of the structure. The three () data channels are described below: Visual imaging is most frequently used for general documentation, as it illustrates the condition of the tunnel liner. The images obtained can be used for visual inspection of the problem areas. By performing regular scans of the same tunnel over a period of time, the data can be accurately superimposed and compared to historical data in each location in order to assess the rate of deterioration and growth of existing defects. Therefore, the Spacetec TS scanner can be used to determine the urgency and necessary frequency of repairs, and has the potential to be used as an assessment tool to categorize the needed repairs based on available budget. Profile data illustrates the tunnel dimensions and can be used to determine tunnel clearances and potential obstruction problems. The profile data can also be used to measure small incremental distances. Because high density scan images are obtained, small surface defects such as chips or spalling of the liner material can be investigated using the built-in -D viewer, which

5 Tabrizi, Celaya, Miller, Wittwer and Ruzzi includes zooming and rotation capabilities. Thermal imaging provides a measurement of the surface temperature of the tunnel lining. Thermography of tunnels provides helpful information beyond what can be seen from visual images or visual on-site inspection. Irregularities in the surface temperature of the tunnel may provide hints related to its structural condition. For example, moisture intrusion, from slight moisture in the lining material up to water infiltrations, is always clearly observed in the temperature due to the cooling effect of the evaporation of water. If sufficient temperature gradients exist, subsurface defects such as voids/delamination/debonding can also be detected. To increase the reliability of the system for this purpose, monitoring of the temperature 0 conditions in the tunnel is necessary before the scanner survey, which can be done by a pre- measurement program. In such a program, temperature sensors are placed in the target structure at various depths. The first sensor measures the air temperature (T surface), the second sensor measures the temperature at a depth of cm (T cm) and the third sensor measures at 0 cm depth (T 0cm). The data are collected and transferred via telephone line. A weather forecast with favorable temperature changes and the confirmation of suitable temperature data via remote access triggers the mobilization of the tunnel scan. Alternatively, the season dependent temperature profile during day and night time can also be used without installing temperature sensors. This provides a more flexible and faster heat flow indication, based on weather observation, but with less accuracy of measured values. For 0 instance, during the summer season, the temperature profile is undulating between maximum (around noon) and minimum temperatures (during night time). This ensures a temperature difference with a proper heat flow. In summary, a general rule to consider is that high temperature differences between day and night time result in good measuring conditions around the temperature maximum (). However, the utility of such a program may be limited by the fact that the optimal time for scanning may not coincide with the availability of the tunnel for scanning. As a result, ignoring this feature of the system (pre-imaging measurement program) may not result in obtaining foolproof debonding/delamination survey of the tunnels. A temperature difference provides clues as to the state of the tunnel lining and is the 0 result of the heat exchange between the inside of the tunnel lining and the air inside the tunnel. The resulting heat flow transports the information from the inside to the surface, where material inhomogeneities become visible as temperature anomalies. A lower heat conductivity of porous material or the air-filled gap of debonded tiles results in a steeper temperature gradient through the tunnel lining. Portable Seismic Property Analyzer (PSPA) The PSPA (Figure ), which determines the variation in modulus with depth of the exposed layer in the field, consists of two ultrasonic sensors or transducers and a source, packaged into a hand- portable system using the Ultrasonic Surface Wave (USW) method (). The PSPA is operable 0 from a laptop computer. The computer is tethered to the hand-carried transducer unit through a cable that carries power and returns the measured signals to the data acquisition board in the computer. The outputs of the two transducers are subjected to signal processing and spectral analyses. In the USW method, the surface or Rayleigh wave velocity, VR, is measured without an inversion algorithm. After VR is measured, the modulus of the top layer, Efield, can be determined from:. 0. E field V R

6 Tabrizi, Celaya, Miller, Wittwer and Ruzzi where ρ is mass density, and is Poisson's ratio. As previously indicated, the dynamic/seismic modulus measured with PSPA can be approximately correlated with concrete strength. In general, larger seismic modulus corresponds to higher concrete strength. A correlation can be obtained if compressive strength from retrieved core samples is obtained at several test points. It should also be noted that the value of the dynamic modulus of elasticity obtained by this test method (ASTM C and C) will, in general, be greater than the static modulus of elasticity obtained by using Test Method ASTM C. The difference depends, in part, on the strength level of the concrete. The PSPA is also capable of conducting Impact Echo (IE) tests. The IE test is conducted using an impact source and a single nearby receiver (as per ASTM C). The source and receiver of the PSPA can be used for this purpose. When a mechanical impact is applied on the surface of a concrete slab, elastic waves are generated in the concrete. The incident waves and the echoes (waves reflected from the boundaries of the slab and the heterogeneities within concrete) are recorded by the receiver. The data analysis includes the transformation of the record into the frequency domain and inspection of the resulting spectrum. As shown in Figure, in the case of an intact slab a large portion of input energy is reflected back from the bottom of the slab. The IE spectrum on the surface of an intact slab of thickness h is, therefore, dominated by a single peak at a frequency fh given by: f h VP h where VP is the compression wave (P-wave) velocity in concrete. The PSPA also enables measurement of the compression wave velocity from: V (. 0.v) P V R In the case of a debonded slab, a portion of the energy will be reflected from the concrete-air interface created by the debonding. A part of the energy may still be reflected from the bottom of the slab. Therefore, other than the full slab thickness frequency fh, the spectrum will show one or more higher frequency peaks at fd = VP/(d), corresponding to the frequency of reflections from the debonding at a depth of d<h. The relative amplitude of the peaks depend on a number of factors, including the extent, depth, continuity, and position of debonding, as well as the frequency content of the impact source. In the case of shallow and large debonding, the solid portion of the slab above the debonding might undergo flexural vibrations. As a result, one or more flexural modes of vibration of this thin concrete section may be excited. Generally speaking, the value of the flexural frequency is significantly lower than the delamination frequency. Furthermore, the amplitude of the surface displacement due to flexural vibrations is higher than the same due to wave reflections ().

7 Tabrizi, Celaya, Miller, Wittwer and Ruzzi Data Acquisition Card Sensor Sensor and Power Supply Ultrasonic Sensors Source Temperature Sensor Amplitude Spectrum Amplitude Spectrum f h f h f d h VP d Intact Debonded 0 FIGURE PSPA detail, typical record obtained and schematic of IE tests. PROJECT SITE The Armstrong and Liberty Tunnels are located in Pittsburgh, PA (see Figure a). The Liberty Tunnel is owned and maintained by District of the Pennsylvania Department of Transportation (PennDOT), and the Armstrong Tunnel by Allegheny County. The Armstrong Tunnel connects Second Avenue, at the South Tenth Street Bridge, to Forbes Avenue between Boyd Street and Chatham Square (see Figure b). The tunnel is characterized by twin bores (or tubes) with a horseshoe cross-section, includes two lanes per tube in the northbound and southbound directions, and a bend halfway through. The approximate length of the tubes is,00 ft and they are internally lined with tiles on the walls and concrete on the ceiling.

8 Tabrizi, Celaya, Miller, Wittwer and Ruzzi a) Tunnel locations b) Armstrong Tunnel North entrance and testing vehicle c) Liberty Tunnel south entrance and testing vehicle FIGURE Tunnel locations, entrance views and TS Scanner mounted on testing vehicle.

9 Tabrizi, Celaya, Miller, Wittwer and Ruzzi The Liberty Tunnel is a pair of tubes that allow motorists to travel between the South Hills of Pittsburgh and the City, through Mount Washington (Figure c). Both tubes have vertical wall horseshoe profiles, each consisting of two ft lanes. The approximate length of the tubes is,00 ft. The posted vertical clearance is ft, in and each tunnel is. ft wide with a maximum height of 0. ft. The tubes are internally lined with concrete, approximately -inches in thickness. Scanning of both northbound tubes was conducted in one night using the Spacetec TS laser scanner. This project also included a limited field validation test program. After submitting the preliminary results, a 00 section of the northbound tube of the Liberty Tunnel was selected for validation purposes. Field validation included the use of the PSPA, coring and limited laboratory testing, which included petrographic analysis. DISCUSSION OF RESULTS Spacetec Laser Scanning Technology: Prior to the laser scanning survey, several deficiencies are normally targeted to be mapped for tracing and inventory purposes. Such deficiencies are dictated by the tunnel owner or their representative. For this study, the aim was to determine the location and quantity of the following deficiencies along the tunnels that were investigated: Surface Cracks o Small< / o Wide >/ o Map Cracking or Crack area: Intersecting pattern of cracks Thermal anomalies: Cold and Warm Tiles Missing/Damaged Efflorescence Honeycombing Refurbished Cracked Patches Ceiling Damage Anomaly (any deficiency not covered) The mapping software, developed by Spacetec, divides the entire scanned area on each tunnel into Zones. Dividing the tunnel into these zones allows for the data to be presented in smaller segments so that all targeted deficiencies are better identified. In this study each mapping zone had a length of about 0 ft. (Armstrong Tunnel) and 00 ft. (Liberty Tunnel). The engineer of record, Mackin Engineering, conducted a detailed base map survey prior to our scanning of the tunnels. In this case, the beginning and end of the tunnel were located at stations 0+00 and +00 (,00 ft.) for the Armstrong Tunnel and 0+00 and +00 (,00 ft.) for the Liberty Tunnel. Typical visual images for an unfolded, 00 ft. long segment in the Northbound tube of the Armstrong and Liberty Tunnels are shown in Figure. As previously indicated, these images are used to visually locate problematic areas.

10 Tabrizi, Celaya, Miller, Wittwer and Ruzzi 0 a) Armstrong (Northbound Tube) 0 b) Liberty (Northbound Tube) FIGURE. Visual image showing a 00 ft. long segment in the tunnels.

11 Tabrizi, Celaya, Miller, Wittwer and Ruzzi 0 Similarly, typical -D images for the tubes, detailing damages on the ceiling and tunnel lining, are presented in Figure. Examples of a visual and thermal image of a segment on the Armstrong and Liberty Tunnels are shown in Figures and, respectively. In Figure, a cold anomaly (due to potential water infiltration) on the tunnel wall is clearly seen. In this case, the cold anomaly could be associated with tile delamination as indicated by markings on the wall from a previously conducted sounding effort. In Figure, potential water infiltrations near the tunnel ceiling are clearly identified, and marked in the figure as indicated by cold anomaly. In both cases, the areas associated with the cold anomalies are mapped (traced). The delineated cold areas, which are indicated on both the visual and the thermal imagery, are stored in the software along with their true locations. 0 0 FIGURE D-View of the surface in the Northbound Tube, with visual damage on the ceiling and visual damage and missing tiles on the wall lining.

12 Tabrizi, Celaya, Miller, Wittwer and Ruzzi a) Visual image 0 b) Thermal image

13 Tabrizi, Celaya, Miller, Wittwer and Ruzzi FIGURE Visual and thermal images obtained on tunnel wall of Armstrong Tube. a) Visual image 0 b) Thermal image FIGURE Visual and thermal images obtained on the ceiling of Liberty Tube. Upon completion of the survey and the analysis/mapping of the tunnel damage, statistical summaries can easily be extracted and reported, indicatingthe distribution of findings over the tunnel length. There is much flexibility in displaying and reporting these results. For example, the overall results, which are summarized from each zone, can be grouped by data sets. The number of findings (count) of each anomaly identified within each zone is presented in Figure for the Armstrong tube and Figure for the Liberty tube.

14 Count Count Tabrizi, Celaya, Miller, Wittwer and Ruzzi 0 Cold Anomaly Warm Anomaly Efflorescence Tiles Missing/Damaged 0 Station a) Thermal and other anomalies Crack < / inch Crack > / inch Ceiling Damage Cracked Patches Station b) Cracks and crack areas FIGURE Distribution of findings over tunnel length (Northbound Armstrong Tube).

15 Count Count Tabrizi, Celaya, Miller, Wittwer and Ruzzi 0 Cold Anomaly Refurbished Honeycombing Station a) Thermal and other anomalies Crack area Crack < / inch Crack > / inch Station b) Cracks and crack areas FIGURE Distribution of findings over tunnel length (Northbound Liberty Tube).

16 Tabrizi, Celaya, Miller, Wittwer and Ruzzi 0 Portable Seismic Property Analyzer (PSPA) Field verification testing was conducted on a selected test area of the Liberty Tunnel using the PSPA. This area included the East concrete lining wall from Sta. +00 to Sta Moreover, a physical inspection using an inspection hammer and delamination wheel was also conducted shortly after the PSPA tests to detect unsound and debonded areas. The objective of the ultrasonic/seismic testing with the PSPA was to measure the dynamic/seismic modulus of elasticity (USW method) of the concrete lining, to conduct Impact Echo (IE) analysis, and to identify areas exhibiting debonding/delamination. The testing was performed using a grid system. A total of twenty-one () stations with a spacing of 0 ft were used over the 00-foot test section, and nine () PSPA test points were selected over the height of the wall between the safety barrier and the tunnel lighting system. From ground level, test points were selected at heights of in, in, in, in, 0 in, in, 0 in, in, and in. As a result, test points were evaluated with the PSPA. In addition, for every test point, up to three () repetitions with the PSPA were performed to measure the variation in the seismic modulus in the vicinity of the test point. A flat-bed hydraulic lift truck was used to have access to each test point (Figure 0). 0 a) Overview of test section b) Mark-out of test points c) Layout of test points d) PSPA testing from lift vehicle FIGURE 0 PSPA testing overview.

17 Tabrizi, Celaya, Miller, Wittwer and Ruzzi The summary of PSPA results is presented in Table. The measured modulus (ksi) at each test point and the average modulus (ksi), standard deviation (ksi), and covariance (%) for each station are included. Based on these results, the modulus at each test point varied from,00 to,0 ksi. Please note that, based on visual observations and correlation with hammer sounding, test points with modulus lower than,0 ksi are highly suspected of being delaminated/debonded. On average, the modulus at each station ranged from, to,0 ksi. The standard deviation and COV for all stations varied from to, ksi and from % to % respectively. Higher variations were obtained at locations having both intact and debonded test points. PSPA results for all test points investigated are also shown in Figure a in the form of a color map. A color scale is provided to the right of the map. Blue and green colors are associated with high modulus values and orange and red colors with low modulus values. As previously indicated, test points modulus lower than,0 ksi (orange and red colors) are highly suspected of being delaminated/debonded. From this figure, it can be observed that the area around Stations +0 and +0 has the biggest concentration of debonding/delamination. To summarize the IE results, a numerical value from to was assigned to all points investigated. corresponds to a severely debonded location, to a moderate debonding/delaminated location, to a slightly debonding/delaminated location and to an intact location. Overall results are summarized in Table (values in parenthesis) and also presented in Figure b in the form of a color map. Blue colors are associated with intact locations and orange and red colors with severely debonded points. A good correlation is observed between these results and the summary moduli results. Overall, it was concluded that there was good correlation between the seismic modulus obtained from the PSPA testing and the areas showing debonding or delamination. Areas of severe debonding were also clearly identified with the IE analysis. However, areas having average or above average modulus either presented frequencies associated with the resonant frequency of the concrete lining or some indication of delamination. Moreover, a comprehensive hammer sounding inspection was performed by Makin Engineering in the 00 ft. verification area to identify areas of debonding or delamination. From that inspection, an excellent correlation between hammer sounding and the PSPA results was found.

18 Tabrizi, Celaya, Miller, Wittwer and Ruzzi Distance from Ground, in TABLE Summary of PSPA Results, Dynamic/Seismic Modulus and IE Results Station and Seismic Modulus, ksi and Debonding Condition () () () () 0 () 0 () () () 0 () 0 () 0 () 0 () 00 () () 0 0 () () () 0 () 0 () () 0 () 0 () 0 () 0 () () () 00 () 0 () 0 0 () 00 () () 0 () () 0 () 0 () 0 () 0 () () () () () () () () 00 () 0 () 0 () 00 () () () () 0 () 0 () () 0 () 0 () 0 () () 0 () () 0 () () 0 () Average Stdev 0 COV, % % % % % % % % () 0 () 00 () 0 () () () () 0 () 0 () () 0 () 0 () () 0 () 0 0 () 0 () () () 0 () 0 () 0 () () () 0 () 0 () () () () 0 0 () () 0 () 0 () 0 () () () 00 () () 0 () () 0 () 0 () 0 () 00 () 0 () () () () 00 () 0 () () 0 () 0 () () () () 0 () 0 () 0 () () 0 () 0 () () 0 () Average Stdev 0 0 COV, % % % % % % % % () () () 0 () 0 () () 0 () () 0 () () 0 () () 0 () () 0 () 0 () 0 () 0 () 0 () 0 () 0 () () 0 () () 0 () 0 () 00 () () 0 () 0 () 0 () 0 () 0 () 0 () 0 () 0 () () () () 0 () () () 0 () 0 () 0 () () 0 () 0 () () () 0 () () () () 0 () 0 () 0 () 0 () 0 () 0 () 0 () () () Average 00 0 Stdev COV, % % % 0% % % % % : Severely Debonded : Moderate Debonded/Delaminated : Slightly Debonded/Deteriorated : Intact

19 Distance from Ground (in) Distance from Ground (in) Tabrizi, Celaya, Miller, Wittwer and Ruzzi Distance from Station +000 (ft) a) Modulus (ksi) results Distance from Station +000 (ft) b) IE results FIGURE PSPA results on east/right wall of Liberty Tube. CONCLUSIONS Documenting the condition of tunnel lining is essential for the planning of future maintenance activities. In this paper it was demonstrated that a comprehensive geo-located mapping of distresses and moisture intrusions, and possibly debonding/delamination (if sufficient temperature gradient exists), with the Spacetec scanner is invaluable. Since all features within the tunnels can be seen and measured, this technology can be confidently used as an asset management tool as well. In Europe, distresses within a tunnel are tracked over time in order to assess their deterioration growth rate and their applicability for repair is based on the available budgets. The visual and profile data channels are used to map all damages/distresses that exist within the tunnel lining. In addition, the thermographic data channel adds considerable value to the routine monitoring of tunnel lining condition. Thermal data contains information which is not accessible from visual images or from visual onsite inspection. They provide a quick overview of the thermal anomalies and hints about conspicuous areas in the tunnel. Having all scanned data (image, profile and thermographic) tied to survey baseline makes the Spacetec system a versatile tool for the follow-up inspections of the tunnels. To demonstrate the benefits of this technology, results from the Armstrong and Liberty Tunnels in Pittsburgh, PA were presented in this paper. Typical findings of damages from the

20 Tabrizi, Celaya, Miller, Wittwer and Ruzzi visual and profile channels were presented. Overall results of the tunnels were also summarized and grouped by data sets. Typical examples of thermal anomalies were also presented. For the case of the Armstrong Tunnel, cold anomalies were associated with tile delamination due to water infiltration behind the tunnel lining. Moreover, from the limited test section investigated with the PSPA, it was found that good correlation exists between PSPA results and areas showing debonding or delamination. PSPA results also correlated well with the hammer sounding from the physical inspection. It can be concluded that PSPA is a useful tool for evaluating concrete deterioration on limited areas of a tunnel. ACKNOWLEDGEMENTS The authors wish to gratefully acknowledge the support of the District of PennDOT, especially Louis Ruzzi, and to acknowledge the assistance of Mackin Engineering for managing the fieldwork and facilitating both the survey and the verification study. Also, the authors would also like to acknowledge the support of the SHRP Program, especially Matt Demarco from FHWA, and Olsen Engineering for their guidance. REFERENCES. Wimsatt, A., White, J., Leung, C., Scullion, T., Hurlebaus, s., Zollinger, D., Grasley, Z., Nazarian, S., Azari, H, Yuan, D., Shokouhi, P., Saarenketo, T. and Tonon, F., Mapping Voids, Debonding, Delaminations, Moisture, and Other Defects Behind or Within Tunnel Linings. SHRP Report S-R0G-RR-. Transportation Research Board of the National Academies, the Second Strategic Highway Research Program, Washington, DC 0.. Gucunski, N., Imani, A., Romero, R., Nazarian, S., Yuan, D., Wiggenhauser, H., Shokouhi, P., Taffe, A., and Kutrubes, D., Nondestructive Testing to Identify Concrete Bridge Deck Deterioration. Strategic Highway Research Program (SHRP) Report S-R0A-RR-. Transportation Research Board, 0.. Sansalone M.J. and Streett W.B., Impact-Echo Nondestructive Evaluation of Concrete and Masonry, Bullbrier Press, Ithaca, N.Y.,.. Celaya, M., Shokouhi, P. and Nazarian, S., Assessment of Debonding in Concrete Slabs Using Seismic Methods, Transportation Research Board. Journal of the Transportation Research Board No. 0, pp -, 00.. Wittwer, A., and Wissler, R., Use of Thermography for Tunnel-Inspection, World-Tunnel- Congress 0, Dubrovnik/Croatia.. Nazarian, S., Yuan, D., Tandon, V., and Arellano, M., (00), Quality Management of Flexible Pavement Layers with Seismic Methods, Research Report -, Center for Transportation Infrastructure Systems, UTEP, El Paso, TX, 0 p.