Completed Projects

A Rational Approach for Rock Slope Designs in PA

Principal Investigator: J.S. Lin
 Co-principal Investigator: Luis Vallejo

Objective: This study is aimed at building a coherent framework that is easily implemented for consistent and reliable designs of rock slopes located in the Pennsylvania Department of Transportation (PennDOT) District 11-0. The framework implemented will contain the following features and capabilities:

  • The incorporation of local geological characteristics that are relevant to the assessment of rock slope stability; and
  • Guidance on the proper application of the Colorado Rockfall Simulation Program (CRSP) in reliably predicting slope performance.

View project document. 

Repair Method of Pre-stressed Girder Bridges

Principal Investigator: Kent Harries

Objective: Since pre-stressed concrete bridges are showing signs of damage and distress, this research reviews current practices and repairs, recommends best practices in concert with PennDOT, and identifies candidate structures for future demonstration projects.

View project document. 

Structural Evaluation of Slab Rehabilitation by the Method of Hydrodemolition and Latex Modified Overlay

Developing a Methodology to Incorporate Transit, Pedestrian and Bicycle Design Features into Highway and Bridge Projects during the Planning and Design phases of Project Development in Pennsylvania

Background: The objective of this research was to develop a more qualitative means of assessing the need for bicycle, pedestrian, and transit facilities in conjunction with highway and bridge projects.

Findings: Data collection, latent demand, level of accommodation and the need for the accommodation of pedestrians, bicyclists and transit users in planning and designing highway and bridge projects was explored.

Results: The testing of three potential methodologies on four current highway and bridge projects explored how these methods could be adapted to Pennsylvania.

Recommendations: Based upon this evaluation, the researchers recommend consideration of a modified Georgia DOT method to replace the current bicycle and pedestrian checklist. The Georgia DOT method provides a more prescriptive methodology and incorporates crash criteria, specifically for pedestrians and bicycles.

Phase 2 - Bridge Scour

Principal Investigator: Dr. Ervin Sejdic

Background: The objective of the research was to develop a production ready float-out device bridge scour monitoring system. Initially, float-out devices are buried around a bridge abutment at specific locations and depths. After a scour event, a float-out device is released and wirelessly communicates with a receiver, located near the bridge. The receiver produces a visual indication to an inspector in the vicinity of the bridge that a float-out device has been released at the specified location and depth.

Findings: After reviewing the Phase 1 prototype, multiple adjustments were required to the float-out device and radio frequency receiver. The float-out device has been modified to comply with durability and operational requirements. The communication frequency and transmission power have been changed to operate within FCC regulation.

Results: An RF transmission distance test, a capsule pressure test and capsule drop test were performed in the laboratory to ensure that the float-out device can withstand a wide range of environmental conditions. The power reset circuitry developed in Phase 2 was tested to ensure the float-out device can remain active for a period of 20 years. During two different river tests, a simulated scour event verified the operation of the scour monitoring system.

Recommendations: Based on the testing performed in Phase 2, the float-out device bridge scour monitoring system can be deployed and remain operational for a period of 20 years. The installation would provide a test case for the implementation of a state wide scour monitoring system.

Slab Stabilization

Jonathan Run Acid Rock Discharge Mitigation Strategies and Implementation Activities

Principal Investigator: Ronald Neufeld

Objective: The overall mission of this project and associated set of objectives is to understand, document and create improvements to Jonathan Run so that it may be restored as a trout fishery.

Freeway Ramp Management

Principal Investigator: Radisav Vidic


Co-principal Investigator: Mark Magalotti

Objective: Because limited funding is available to add capacity to urban freeway systems in Pennsylvania, traffic management solutions are needed to reduce congestion. One cost-effective type of traffic management solution is the use of ramp management. Since ramp metering was introduced many years ago advances have been made in traffic control and surveillance systems that makes ramp management a traffic congestion management tool that can be used in conjunction with the traffic management centers that have been put in operation in Pennsylvania. Ramp management includes four potential strategies for the operation of freeway ramps; they include ramp metering, ramp closure, special use treatments, and ramp terminal treatments. The objective of this research will be to the best practices available in ramp management that maybe used in Pennsylvania and to evaluate the feasibility and potentially design the concept of a ramp metering demonstration project in PennDOT District 11-0.

Sensing Technology for Damage Assessment of Sign Supports and Cantilever Poles

Principal Investigator: Piervincenzo Rizzo

Objective: The objective of this work is to develop and deploy a robust and low-cost sensing technology to assess the structural soundness of sign supports, cantilever poles, and variable message sign (VMS) supports. An analytical model will be initially developed to correlate stress-crack severity and/or location to their structural integrity and residual lifetime. Thus, the sensing technology, by detecting location and size of any defect, will provide a means for PennDOT to predict the residual lifetime and to establish the need for replacement or retrofit. The proposed activities will include efforts in the following areas: finite element modeling, nondestructive evaluation (NDE), structural health monitoring (SHM), fatigue life prediction, and sensor technology development. The project will quantify the dynamic characteristics of in-service structures analytically, and will investigate the effect on the residual structures’ life of stress-cracks located at critical elements. An effective NDE/SHM system will be proposed and developed. Fatigue tests will be performed at the Watkins-Haggart laboratories to validate the analytical model and the NDE/SHM approach. Simultaneously, the system will be tested in the field at locations determined by PennDOT to obtain actual field condition information. The impact of this work on the transportation industry lies on the implementation of a cost-effective strategy that will prevent structural failures that may lead to catastrophic collapses. In addition, the early detection of damage will allow stopping further damage propagation and will prolong the structure’s lifetime by taking appropriate remedial actions such as repair or retrofit.

View project document. 

Impacts of Vanpooling in Pennsylvania and Southwestern Pennsylvania and Future Opportunities

Principal Investigator: Melissa Bilec


Coprincipal Investigator: Sabina Deitrick

Objective: The objective of this work is to analyze the current conditions for vanpooling in Pennsylvania with an emphasis on Southwestern Pennsylvania, review the current programs of Southwestern Pennsylvania Commission and other vanpooling operations, and develop a model for an expansion of vanpooling programs. In addition, we will assess the vanpooling options today and what new options can be developed under different funding and agency scenarios. 
Vanpooling offers a low-cost alternative transportation option for many commuters. Vanpools typically carry 7-15 passengers. Their flexibility, convenience, relative cost advantage, and contribution to reducing traffic congestion make vanpooling programs increasingly popular. Vanpooling is increasing today with fuel prices. The number of vanpools in the country declined from 15,000 in 1980 to 8,500 in 1999 and now is well over 10,000 again. This study will examine vanpooling options and promotion of vanpooling by Pennsylvania and PennDOT. We will focus on Pennsylvania and on Southwestern Pennsylvania and its 10-county region, analyzing vanpooling in the Southwest Pennsylvania Commission (SPC) area, but will also examine other parts of the state, including rural areas.

Deterioration of J Bar Reinforcement in Abutments and Piers

Principal Investigator: Kent Harries

Coprincipal Investigator: Melissa Bilec, Jason Monnell

Objective: The objective of this project is to determine the extent and nature of deterioration and/or necking of J-bars in existing abutment, pier, and retaining wall footings so that the condition can be addressed using appropriate repair or rehabilitation methods.

Assessment Strategies of Fire Damaged Bridges

Principal Investigator: Kent Harries

Objective: The objective of this research is to develop simple tools to evaluate the effects of fire damage on the structural properties and load capacity of steel bridge elements. This is very specialized work. Based on discussions with PennDOT and Purdue University (Purdue) and an existing relationship between PennDOT, Pitt and Purdue, several tasks involved in this project are to be subcontracted to Purdue University.

Premature Deterioration of Jointed Plain Concrete Pavements

Principal Investigator: Julie Vandenbossche

Objective: The majority of the jointed plain concrete pavements (JPCP) constructed in Pennsylvania perform with little maintenance throughout the intended design life. Many perform well beyond their intended design life while carrying substantially more traffic than what they were designed to carry. There are some pavements that have exhibited early distress in the first five to ten years after construction. The maintenance/repairs generated by this early deterioration can generate substantial costs for a pavement type that is typically considered to be relatively maintenance free. The objective of this research effort is to help identify the cause of this premature deterioration so that it can be prevented in future projects and also provided guidance on how to address this deterioration once it has developed.

View project document. 

Establish Inputs for the New Rigid Component of the M E Pavement Design Guide

Principal Investigator: Julie Vandenbossche

Objective: The three primary phases required for the adoption of the new Mechanistic-Empirical Pavement Design Guide (MEPDG) for Rigid Pavements by PennDOT consist of the following: identify critical inputs, identifying and meeting data needs, and verification/calibration/implementation

View project document. 

Local Technical Assistance Program (LTAP) Course Development

Principal Investigator: Radisav Vidic


Course Developers: Melissa Bilec, Amy Landis, Mark Magalotti

Objective: The Department of Civil and Environmental Engineering at the University of Pittsburgh appreciates the opportunity to work with the Pennsylvania State Association of Township Supervisors (PSATS) and the Pennsylvania Department of Transportation (PennDOT). Based on correspondence, we are prepared to develop the following two courses: (1) Traffic Signal, How to Study, Install, and Maintain them in Pennsylvania, and (2) Everyday Sustainability for use in the PennDOT Local Technical Assistance Program (LTAP).

A Study of Highway Subsidence due to Longwall Mining using data collected from I-79

Principal Investigator: Luis Vallejo


Co-principal Investigator: J.S. Lin

Objective: This study is proposed to study the field measured highway subsidence data collected by PennDOT under I-79 Highway resulting from the longwall mining. The objectives are to determine which of the existing models gives the best prediction, and to investigate the possibility of modifying these models if necessary. The data collected by District 12 on the subsidence taking place under I-79 highway will be used. The study framework implemented will contain the following features:

  • Collect and study the geological profiles and ground displacement records obtained during the longwall mining of the Emerald Mine and Cumberland Mine under I-79 Highway. The longwall mining will cover the following panels: Emerald B3, Emerald B4, and Emerald B5 and Cumberland LW 49, LW 50, LW 51, LW 52, and LW 53.
  • Study the subsidence profiles created by the longwall panels mentioned above.
  • Comparison of the measured subsidence profiles with the ones obtained using the Surface Deformation Prediction System (SDPS) model developed by the Office of Surface Mining.
  • Prediction of future subsidence as the panels mentioned above advance in the years ahead.

View project document. 

Market Analysis of Construction Materials with Recommendations for the Future of the Industry

Principal Investigator: Melissa Bilec


Coprincipal Investigator: Joe Marriott

Objective: The objective of this work is to perform a market analysis and forecast for key commodities used in the highway and bridge construction industries including oil/asphalt, cement/concrete, steel, aggregates, and chemicals. This forecast will provide a basis for recommendations on future commodity use, new technologies, environmental issues, and construction practices and/or substitution commodities for PennDOT to consider for future development.

Biodiesel Fuel Feasibility Study

Principal Investigator: Amy Landis

Coprincipal Investigator: Melissa Bilec

Objective:The objective of this work order is to advise PennDOT during their District 8 pilot fleet transition to biodiesel. The University will provide information and recommendations on best practices for current biodiesel (B5) implementation, and for other possibilities for biodiesel implementation including additional biodiesel formulations (eg., B20, B100 and the relationship between manufacturers’ recommendations and warranties). The University will also provide recommendations with respect to measures to be taken to meet 2010 federal emissions requirements. The analysis will include information on economic impacts and environmental impacts, along with evaluating performance, for the pilot study and statewide implications. Collaboration with other state agencies (i.e. DEP) is anticipated.

Remote Sensing Bridge Scour

Principal Investigator: Marlin Mickle


Co-principal Investigator: Peter Hawrylak

Objective: Bridges over waterways such as streams and rivers have foundation structures that extend down into the stream or river beds. These structures are surrounded by alluvial soil and other materials that protect the bridge foundations. During flood events the stream flow velocities are such that there is a tendency for the alluvial soils to wash away. This process is termed scouring. PennDOT has been looking for a real time solution to detect this scouring without success over the last few years. During flooding, they can send a crew to check the bridges, but it is difficult to see below the surface of the water to determine if scouring has taken place to a level where the bridge needs to be closed. The objective is the development of a sensor and sensor system that can be used to produce a visual indication to an inspector in the vicinity of the bridge that scouring has taken place and possibly to what level. Through relatively straightforward communications channels, the system could be enhanced so that the reporting mechanism is directed to a central facility from numerous remote locations.

Evaluation of Bridge Cleaning Methods on Steel Structures

Principal Investigator: Dr. Julie Vandenbossch

Background: Corrosion due to soluble salts is a major factor in the lifespan of the bridges and their protective coating. However, deicing salts are required to maintain the serviceability of the transportation infrastructure during winter months. Therefore, it is beneficial to develop a bridge washing program, which can remove soluble salts from steel bridge members. This study evaluated the Pennsylvania Department of Transportation (PennDOT) procedures for bridge washing.

Findings: It was found that using water without any cleaning agents is effective in removing soluble salt from steel bridges as long as good practices are followed while washing the bridge and the bridge coating is intact. Washing was found to be ineffective if the pressure used was significantly below the 1750 psi prescribed by PennDOT, the surface being washed showed significant evidence of coating failure and corrosion, or if the washer nozzle was too far below the target area for the pressure being used. From a programming stand point, it was found that members directly above a roadway contained high concentrations of soluble salts and are not currently required to be cleaned. On the other hand, the full length of the truss and arch members below the bridge deck are currently being cleaned and did not have large surface salt concentrations for the bridges evaluated. It was also determined that the wash water generated during the bridge washing process did not adversely affect the surrounding environment.

Results: The pre-wash soluble salt concentration ranged from 8mg/m2 (11x10-3 grains/ft2) on several areas that were not directly exposed to salt, and were rinsed by rain, to as high as 1133 mg/m2 (1624x10-3 grains/ft2). This was measured on the bottom flange of a diaphragm beam directly below a leaking expansion joint. The highest pre-wash surface salt concentration on an area not currently required to be washed under PennDOT specifications was 298 mg/m2 (427x10-3 grains/ft2). This location was on the top side of the bottom flange of a girder above a roadway. Washing efficiencies ranged from 95 percent when salt concentrations were high and the equipment was working properly to 0 percent (no statistically significant difference). The latter occurred when the equipment was not properly functioning and the water pressure was low. All heavy metal concentrations measured in the waste wash water were below the levels prescribed in the Pennsylvania Code, Chapter 93.

Recommendations: As the result of this study, the following recommendations have been made:

  • The CMMT and PennDOT Publication 55 are not in agreement on the frequency in which bridges are to be washed and should be changed so that they are consistent.
  • The area of a steel bridge directly beneath a leaky expansion joint should be washed frequently until a repair can be made. The joint itself should also be flushed to remove any residual salts, which typically accumulate in the joint.
  • Overhead members extending horizontally across the roadway and within 7 m (23 feet) of roadway surface exhibited high salt concentrations and washing of these areas would appear to be beneficial.
  • Locations in the vicinity of connections exhibited high salt concentrations and washing of these areas would appear to be beneficial.
  • Washing was found to be ineffective for the bridges evaluated when a majority of the coating had failed.
  • Pressurized water was sufficient to clean bridges when the surface is intact and therefore chemicals are not recommended for cleaning in these areas.
  • A pressure gage should be installed and monitored on all equipment to ensure cleaning occurs at the prescribed pressure.

 

Tree Canopied Highway vs. Clear Highway Corridors

Principal Investigator: Radisav Vidic


Co-principal Investigator: Mark Magalotti

Objective:In the current economic climate, states all around the country are seeing budgets tighten and assets continually reallocated. The Pennsylvania Department of Transportation (PennDOT) is no exception and is constantly being asked to do more with less. This is particularly true of PennDOT highway maintenance forces, which must care for each and every state-owned roadway in the Commonwealth of Pennsylvania. Pennsylvania’s variable weather and predominantly rural landscape further add to the enormity of this task. As a result of these factors, maintenance efforts must be carefully and thoughtfully considered. This is especially true of the policy towards maintenance of trees and tree canopies within highway rights-of-way. Any policy developed must be safe for all road-users, cost effective, and balance environmental and aesthetic impacts and considerations. The objective of this research project will be to design and establish a framework for study to ultimately determine how highway corridors with or without tree canopies in Western Pennsylvania compare relative to safety, costs to maintain through trimming or clear cutting in the right-of-way on planned cycles, maintenance of the road and roadside vegetation, and cost to maintain during the winter. Broad-based best practices for tree and canopy trimming within the highway right-of-way will be developed as part of this research effort. Implementation of these trimming best practices will be performed under future phases of the research project as funding allows.

Structural Evaluation of Slab Rehabilitation by the Method of Hydrodemolition and Latex Modified Overlay

Principal Investigator: Dr. Kent Harries

Background: The primary objective of this study was to assess the validity of PennDOT Publication 15 Section 5.5.5.1, specifically that “a latex overlay is not considered structurally effective”, in terms of the structural response of the bridge superstructure.

Findings: This study has demonstrated the effectiveness of PennDOT Method 2 LMC (latex-modified concrete) overlays for Type 1 and 2 bridge deck repairs. The LMC clearly contributes to the load carrying capacity of the rehabilitated deck slab. With this conclusion, it is envisioned that more bridges that would otherwise be subject to complete deck replacement may be viable candidates for overlay repair.

Results: Several parameters were varied amongst full-scale test specimens in an experimental program: overlay depth, removal of concrete ‘shadows’ under primary reinforcement bars, and the direction of bending. The LMC-repaired slabs acted as monolithic slabs in all cases and the capacity was uniform regardless of LMC depth. The LMC interface has essentially no impact on the behavior of the repaired slabs. The anticipated capacity of an LMC overlaid deck may be estimated as that of the original full-depth deck. Experimental capacities were seen to exceed this value in all cases. Simple plane-sections analyses are suitable for obtaining these capacities. Finally, it was demonstrated based on fundamental mechanics and shear friction theory that LMC interface stresses are relatively low and unlikely to exceed reasonable values of capacity for properly constructed LMC overlay repairs typical of slab-on-girder bridges.

Recommendations: It is recommended that LMC overlays exceeding 1.25 inches in depth may be considered structurally effective in load rating a bridge deck. This assumes that the overlay in question has been constructed to an appropriate standard using ‘best practices’ described in the document. Furthermore, it is recommended that a pull-off testing program be establish for quality assurance purposes in accordance with ASTM C1583. A ‘commentary’ on this test method is provided to clarify its use for this specific application. Additionally, acceptance criteria for such testing are proposed as follows: If the pull-off strength exceeds 200 psi, it is believed that the interface shear capacity will be adequate and the overlay will behave in a fully composite manner with the substrate concrete. For pull-off capacities less than 200 psi, the mode of failure is telling. If the failure remains in the substrate (Mode S), the interface is stronger than the substrate and the shear capacity is at least that of the residual substrate concrete. In such a case, composite behavior of the overlay is likely. Pull-off tests indicating an interface failure (Mode I) are cause for further investigation. Pull-off tests less than 100 psi, regardless of failure mode should not be accepted.

Bridge Waterproofing Details

Principal Investigator:  

Background The objective of this research is to improve the safety margin and redundancy of current waterproofing details used for bridge substructures in PennDOT practice.

Findings: Based on literature review, field visits, inspection reports, structural analysis and experimental tests, the key components of the waterproofing system were studied. Their strength and robustness were analyzed and evaluated based on the damage development and failure modes.

Results: The inadequacy in the key components of current waterproofing system is assessed and remedies to mitigate water leakage are proposed for PennDOT practice

Recommendations: Based upon the evaluation on strength and redundancy, executable recommendations are proposed to strengthen the waterproofing details at critical locations. The proposed practice not only strengthens the waterproofing details, but also provides advantages in repair cost and inspection.

Improved Performance of Jointed Plain Concrete Pavements (JPCP) Through a Better Awareness of Drying Shrinkage

Principal Investigator: Dr. Qiang Yu

Background Long-term drying shrinkage and early-age plastic shrinkage cracking can affect the performance of jointed plain concrete pavements (JPCPs). The plastic shrinkage cracks develop while the concrete is still fresh. This occurs when the rate of evaporation of the moisture on the surface of the concrete exceeds the bleeding rate. While plastic shrinkage cracking affects the durability, long-term drying shrinkage affects the fatigue life. This study evaluates current Pennsylvania Department of Transportation specifications and practices pertaining to the paving mix design and construction, specifically finishing and curing, and their effects on long-term performance. This specification review was supplemented by a laboratory study to evaluate curing and mix design enhancements.

Findings: A review of the performance of in-service pavements revealed plastic shrinkage cracks commonly develop in JPCP constructed in Pennsylvania. The curing and finishing construction practices and specifications were reviewed to identify potential causes and it was found that improvements could be made to reduce the potential for plastic shrinkage cracking. These improvements address both the type of curing compound used as well as the method used for application. It was also found that excessive water added to the pavement surface during the burlap drag finishing is increasing the water-to-cement ratio at the surface, and thereby reducing the strength. This increases the potential for plastic shrinkage cracking as well. Finally, it was determined that the drying shrinkage could be decreased and the durability increased if the water-to-cement ratio was lowered and a more densely graded aggregate specified.

Results: The curing compound study performed revealed statistically significant differences between the different curing methods. The moisture loss was lower and the early-age concrete material properties, specifically compressive strength and permeability, were improved for specimens with the poly alpha methylstyrene resin cure. Additionally, the specification review and site visits revealed that PennDOT would benefit from removing the wet burlap drag from the finishing process unless it is being used to provide texture for the final finish. Currently any texture provided by the drag is being removed by the finishers working behind the drag and, at times, the process is used to add excessive moisture to the pavement surface. The mix design investigation revealed that both lowering the water-to-cement ratio and using a more densely-graded aggregate, as compared to current PennDOT paving mixes, will result in a lower cement demand and therefore less shrinkage. The mix would also be less susceptible to segregation and durability issues.

Recommendations: As a result of this study, the following recommendations have been made:

  • PennDOT should require a curing compound with a poly alpha methylstyrene resin rather than the currently required wax-based compound.
  • A denser aggregate gradation in the paving mix would reduce the cement demand and therefore reduce drying shrinkage and increase durability. The Shilstone methodology can be used for establishing this gradation.
  • A target 0.40 water-to-cement ratio is recommended for paving mixes.
  • The practice of pulling a soaked burlap drag immediately behind the paving equipment but before the finishing practice should be eliminated. If used, the wet burlap drag should occur after finishing and only to add texture but without adding excessive water to the surface.
  • The application of liquid membrane forming curing compounds should be done exclusively with mechanized equipment for mainline paving and no hand spraying should be allowed to avoid a nonuniform application.