Research results
2012 Technical Summaries/Reports
2013 |2012 | 2011 | 2010 | 2009 | 2008 | 2007 | 2006 | 2005
Estimation of Winter Snow Operation Performance Measures with Traffic Data
This research produced an automatic process to identify the road condition recovered times during snow events from the traffic-flow data. For this study, the traffic data from the past snow events were analyzed and the speed variation patterns indicating the road condition recovery states during the recovery periods were identified. The prototype process developed in this study finds the speed change point indicating the recovery of the road condition by analyzing the speed variations for a given location. The process was then applied to a set of the past snow events and the estimated recovered times were compared with the reported lane-regain time data.
Final Report: 201240 (PDF, 3.1 MB, 56 pages)
MnROAD Study of RAP and Fractioned RAP
Recycled Asphalt Pavements (RAP) and Fractioned Recycled Asphalt Pavement (FRAP) were tested for field and laboratory performance at the Minnesota Road Research Project (MnROAD) facility between 2008 and 2012. Project scop included: developing specifications, construction, and field and laboratory evaluation of materials.
Final Report: 201239 (PDF, 395 KB, 23 pages)
Development of a Weigh-Pad-Based Portable Weigh-In-Motion System
The objective of this project was to develop a portable WIM system that would be used much like a pneumatic tube counter. The developed system is battery operated, low cost, portable, and easily installable on both rigid and flexible pavements. The report includes a sideby- side comparison of data between the developed on-pavement portable WIM system and an in-pavement permanent WIM system.
Final Report: 201238 (PDF, 3 MB, 87 pages)
2011 MnROAD Mainline Concrete Construction: Cells 5, 6, and 63
In September 2011, MnDOT constructed two cells in the MnROAD Mainline in continuation of the study of unbonded overlay (Cell 5) and to facilitate studies on a drainable base (Cell 6) with a longitudinal tined texture. Additionally, roller compacted concrete shoulders were constructed in these cells, to replace the preexisting asphalt shoulders. Finally, repairs were done to a thin concrete overlay of existing asphalt pavement installed in 2004 (Cell 63). This report discusses the construction procedure, instrumentation, and the initial monitoring from these test cells.
Final Report: 201237 (PDF, 8 MB, 96 pages)
The objective of this project was to chracterize the properties of crushed recycled concrete (RCA) and asphalt pavement (RAP) as unbound base without being stabilized, to assess how RCA and RAP behave in the feild and to determine how pavements can be designed using RCA and RAP. Issues to be considered include variability in material properties, purity of material, climatic effects, how to identify and control material quality, and leaching characteristics.
Final Report: 201235 (PDF, 7 MB, 340 pages)
Access to Destinations: Annual Accessibility Measure for the Twin Cities Metropolitan Area
The Access to Destinations research project, begun in 2006, is a multi-stage investigation into the detailed measurement of accessibility across the Twin Cities metropolitan area. Its goal is to define a practical measurement, and a process for conducting that measurement, that can be implemented on a recurring basis to support planning and performance evaluation of a multi-modal transportation system.
Final Report: 201234 (PDF, 9.7 MB, 78 pages)
Pooling Our research: Loop- and Length- Based Vehicle Classification, Federal Highway Administration
This report analyzes various length-based vehicle classification schemes using geographically diverse data sets. This report also conducted field and laboratory tests of loop and non-loop sensors for their performance in determining vehicle length and vehicle speed.
Final Report: 201233 (PDF, 3 MB, 106 pages)
The 2012 Changeable Message Sign (CMS) Manual of Practice report is intended as a replacement of the agency's 2000 statewide technical document which outlined standard practice in the use of agency CMS. The 2012 document includes information derived from existing FHWA standards, MUTCD requirements, the MnDOT 2012 Field Manual and CMS/DMS best practices identification from twelve other state departments of transportation.
Final Report: 201232 (PDF, 1.9 MB, 67 pages)
Implementation, Training, and Outreach for MnDOT Pavement Marking Tool - Phase II
The objective of this project was to fully implement the Pavement Marking Management Tool by incorporating retroreflectivity and striping data (MnDOT and contractors) and simplifying the process of data collection, storage, and analysis. As part of achieving full implementation, the researchers provided training to MnDOT central office staff and staff in each of the districts. Improved pavement marking management has the potential to reduce MnDOT's costs, improve pavement marking performance, and in return provide a more efficient and safe driving experience for the traveling public.
Final Report: 201231 (PDF, 6.5 MB, 67 pages)
Full-Depth Precast Concrete Bridge Deck System: Phase II
The Minnesota Department of Transportation (MnDOT) has developed a design for a precast composite slab-span system (PCSSS) to be used in accelerated bridge construction. The system consists of shallow inverted-tee precast beams placed between supports with cast-in-place (CIP) concrete placed on top, forming a composite slab-span system. Suitable for spans between 20 and 60 ft., the MnDOT PCSSS is useful for replacing a large number of aging conventional slab-span bridges throughout the United States highway system. The PCSSS has particular durability, constructability, and economical concerns that affect its value as a viable bridge design. To address these concerns, the performance of existing PCSSS bridges was evaluated and a review of a number of PCSSS design details was conducted.
Final Report: 201230 (PDF, 8.6 MB, 204 pages)
Composite Pavements and Exposed Aggregate Texturing at MnROAD: Cells 70, 71, and 72 Construction Report and Early Performance Evaluation
This report summarizes the construction and early performance assessment of three composite (new, multi-layer, construction) test cells at the MnROAD: HMA over a recycled aggregate concrete; diamond grind concrete over recycled aggregate concrete; and exposed aggregate concrete over a low cost concrete. Strength, on board sound intensity, sound absorption, friction, texture and international roughness index were tested to better understand the performance of these, pavement types.
Final Report: 201229 (PDF, 5.1MB, 84 pages)
Investigation of Pedestrian/Bicyclist Risk in Minnesota Roundabout Crossings
This project was developed to investigate pedestrian accessibility in Minnesota urban roundabouts, addressing complaints from pedestrians regarding difficulties in crossing and safety. The methodology followed in this ongoing research is typical of other observational studies. A sufficiently large number of observations on the interactions between pedestrians or bicycles (peds/bikes) and vehicles at two modern urban roundabouts in the Twin Cities of Minneapolis and St. Paul in Minnesota were collected and reduced. These observations have supported a two phased analysis. Phase 1 involved the extraction of general information describing the crossing event, such as who yielded, the location of the crossing, or the number of subjects involved. Phase 2 looked deeper into these factors by considering the conditions inside the roundabout before the vehicle proceeds to the crossing and meets with the ped/bike.
Final Report: 201228 (PDF 3.1 MB, 78 pp)
A Research Plan and Report on Factors Affecting Culvert Pipe Service Life in Minnesota
Culvert pipe material selection has traditionally been a relatively simple task involving metal or concrete pipe. In recent years, the addition of coated metal and plastic pipe has led the federal government to implement a rule requiring the consideration of alternative pipe materials. The current MnDOT Drainage Manual provides limited guidance on the selection of pipe material. The manual is lacking detailed information on the influence of environmental conditions on pipe durability in Minnesota. It is necessary to provide updated, accurate information on pipe material and durability for factors directly related to Minnesota.
Final Report: 201227 (PDF 1.6 MB, 88 pp)
Construction Manager/General Contractor Issue Identification
The construction manager-at-risk (CMR) project delivery method, also termed construction manager/general contractor (CM/GC) project delivery in several states' enabling legislation, is an integrated team approach to the planning, design, and construction of a project to control schedule and budget and assure quality for the project owner. The team consists of the owner, the designer, which might be an in-house engineer, and the at-risk construction manager.
Final Report: 201225 (PDF 930 KB, 81 pp)
Instrumentation, Monitoring, and Modeling of the I-35W Bridge
The new I-35W Bridge was instrumented incorporating "smart bridge technology" by Figg Engineering Group in conjunction with Flatiron-Manson. The purpose of the instrumentation was to monitor the structure during service, and to use this information to investigate the design and performance of the bridge. Finite element models were constructed, taking into account measured material properties, to further explore the behavior of the bridge. This report documents the bridge instrumentation scheme, the material testing, finite element model construction methodology, the methodology and results of the truck tests, validation of the models with respect to gravity loads and thermal effects, measured and modeled dynamic modal characteristics of the structure, and documentation of the investigated assumptions from the Load Rating Manual.
Final Report: 201224 (PDF 35.3 MB , 352 pp)
Investigation of Low Temperature Cracking in Asphalt Pavements National Pooled Fund Study - Phase II
A number of significant contributions were made in phase two of this comprehensive research effort. Two fracture testing methods are proposed and specifications are developed, alternative methods to obtain mixture creep compliance, and a new thermal cracking model, called "ILLI-TC," is developed and validated. All of these are important for the continuation of proper asphalt research and propigation.
Final Report: 201223 (PDF 13.9MB, 377 pp)
Investigating the Effectiveness of Intelligent Lane Control Signals on Driver Behavior
A fully interactive PC-based STISIM driving simulator was used to test the effectiveness of Intelligent Lane Control Signals (ILCS). The participants were 160 licensed drivers from four age groups: 18-24, 32-47, 55-65, and 70+ years of age. Each participant drove three times in a counterbalanced order. In each trial, after driving five miles in the center lane of a six-lane highway where the speed limit was 65 mph, they encountered five sets of ILCSs that occurred at half-mile intervals.
Final Report: 201222 (PDF 1.3 MB, 72 pp)
Concrete Slurry, Wash and Loss Water Mitigation
This report presents an evaluation of wastewaters derived from concrete placement and maintenance and the preparation of best management practices (BMPs). Investigation and documentation of existing practices was done to ensure application to real situations and enhancement of constructability for all BMPs. Laboratory analysis of test specimens was done to provide characterization of factors that are likely to positively or negatively influence concrete wastewater composition. Evaluation of sedimentation and filtration through and absorption by sand and geotextile materials provides a simulation of the known control techniques.
Final Report: 201221 (PDF 33 MB, 223 pp)
Salt Brine Blending to Optimize Deicing and Anti - Icing Performance
This project developed a spreadsheet-based evaluation tool to compare the relative ice melt capacity and cost-effectiveness of granular and liquid deicers across a range of temperatures. A second phase of this research will validate and expand on lab results with field tests on actual pavements.
Technical Summary: 201220TS(PDF 882 KB, 2pp)
Final Report: 201220 (PDF 10.6 MB, 151 pp)
Potential Benefits of Mileage- Based User Fees to the Freight Industry and Industry Concerns
The concept of mileage-based user fees has seen increasing support from a number of groups in recent years; however, it faces opposition from many in the general public, and in particular from the trucking industry – which largely objects to this approach to funding transportation. This paper is part of a larger effort exploring the benefits to the freight industry of mileage-based user fees, while highlighting industry concerns over its implementation.
Final Report: 201219 (PDF, 1.8 MB, 58 pages)
Subgrade Stabilization ME Properties Evaluation and Implementation
Researchers investigated methods and materials for stabilizing pavement subgrades to establish mechanistic empirical design parameters for the resilient modulus of stabilized roads. Results showed that there is a large variability in the degree to which stabilization improves the strength and stiffness of subgrade materials. Consequently, researchers could not identify one factor of improvement for a given combination of stabilization material and method. Instead they recommended that a procedure be followed on a project-by-project basis to identify an appropriate stiffness resistance factor during the course of project predesign and design. By collecting data on project-specific improvement factors, MnDOT will eventually be able to develop more general improvement factors. Doing so will reduce project costs by facilitating more precise pavement designs.
Technical Summary: 201218TS (PDF)
Final Report: 201218 (PDF 1 MB, 139 pp)
Material Testing Rates for Low-Volume Roads
Researchers reviewed MnDOT's existing Schedule of Materials Control (SMC) for its applicability to smaller projects by local agencies on low-volume roads. They created a new State Aid for Local Transportation program SMC for low-volume roads tailored specifically to the construction project risks encountered by local agencies, which reduces materials testing rates for low-volume projects without an unacceptable increase in risk. These guidelines incorporate feedback from MnDOT, local agency representatives and the construction industry, and include changes that remove some testing and inspection requirements and make others less stringent.
Technical Summary: 201217TS (PDF 812.5 KB, 2 pp)
Final Report: 201217 (PDF 5.3 MB, 32 pp)
Validation of Prestressed Concrete I-Beam Deflection and Camber Estimates
Researchers developed a new method for predicting the release and erection cambers of Minnesota bridge girders by investigating the factors affecting their accuracy, including thermal effects, concrete strength and stiffness, solar radiation, relative humidity, concrete creep and shrinkage, length of cure and storage conditions. They developed prediction methods that on average improved release camber prediction accuracy from 74 percent to 99 percent, and erection camber prediction accuracy from 83 percent to 95 percent.
Technical Summary: 201216TS (PDF 772 KB, 2 pp)
Final Report: 201216 (PDF 3 MB, 205 pp)
Lump Sum Estimating: Discovery and Simulation
Researchers evaluated the cost-effectiveness of changing from a unit pricing to a lump sum bidding process by comparing these methods with respect to total bid amount, time necessary for inspection, and the attitudes of contractors and MnDOT personnel. Results showed that the lump sum process is viable and produces similar bid results as the traditional process. Using lump sum bidding would require an improvement in the accuracy of construction plans as well as new guidance and training for inspectors whose responsibilities would shift from tracking quantities to performing quality control and assurance.
Technical Summary: 201215TS (PDF)
Final Report: 201215 (PDF 550 KB, 32 pp)
Highway Cost Allocation and Determination of Heavy Freight Truck Permit Fees
Researchers evaluated highway cost allocation methodologies, used this evaluation to customize the FHWA's HCA tool for Minnesota purposes, and performed HCA studies using both the FHWA tool and the Minnesota-centric tools. Researchers also evaluated the best tax structures for equitably collecting revenue and a method for optimizing the pricing of heavy vehicle special permits. Results showed that heavy vehicle users are not taxed proportionately to their impacts on Minnesota roads.
Technical Summary: 201214TS (PDF)
Final Report: 201214 (PDF 1.1 MB, 94 pp)
Assessment and Recommendations for the Operation of Standard Sumps as Best Management Practices for Stormwater Treatment (Vol. 2)
Researchers evaluated the effectiveness of standard sumps for removing and retaining sediments from stormwater runoff. While these sumps were effective for water moving at low rates from urban drainage basins smaller than four acres, they were unable to prevent captured sediments from washing out under high flow rates. The SAFL Baffle retrofit device developed in the second part of this study dramatically reduces this washout rate, making standard sumps very effective water treatment devices at one-fourth the prior cost.
Technical Summary: 201213TS (PDF 762 KB, 2 pp)
Final Report: 201213 (PDF 4.7 MB, 108 pp)
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Porous Asphalt Pavement Performance in Cold Regions
Full-depth porous asphalt test sections at MnROAD performed well in terms of draining and filtering water, providing excellent traction and noise absorption, and hastening snow and ice melt. While the test sections did exhibit rutting and surface raveling problems, their overall performance was acceptable and may well suit low-volume and reduced loading applications.
Technical Summary: 201212TS (PDF 1 MB, 2 pp)
Final Report: 201212 (PDF 17 MB, 204 pp)
Mileage-Based User Fee Policy Study: Supporting Technical Information
The MBUF Policy Study was commissioned by the Minnesota Department of Transportation (MnDOT) to identify and evaluate issues related to potential future implementation of an MBUF system in Minnesota. Under a potential MBUF system, drivers would be charged based on the number of miles they drive, regardless of the type of energy source used to propel the vehicle, instead of being charged by the gallon for fuel consumed in operating a vehicle.
Final Report: 201211 (PDF 9.9 MB, 218 pp)
Use of StreetPave for Design of Concrete Pavements for Cities and Counties in Minnesota
This study compared RigidPave to StreetPave with a review of the input variables and design inputs used by surrounding departments of transportation. Existing thin (six inches or less) concrete pavements were also evaluated, which included both city and county pavements and test cells at MnROAD.
Final Report: 201210 (PDF 784 KB, 56pp)
Development of Best Practices for Inspection of PT Bridges in Minnesota
. Researchers conducted inspections of post-tensioned bridges built in Minnesota before 2003 and updated current bridge inspection procedures so that problems in these bridges can be detected and addressed. In general, the inspected bridges were in good overall condition. Invasive testing showed that one of the three bridges inspected showed no strand corrosion or grouting problems, one had major corrosion problems related to construction issues but appeared to have good grout, and one had significant problems with grouting and the beginning of corrosion. A follow-up implementation project will conduct a more detailed investigation of grouting in post-tensioned bridges.
Technical Summary 201209TS (PDF 701 KB, 2 pp)
Final Report: 201209 (PDF 11.6 MB, 213 pp)
Effects of Implements of Husbandry (Farm Equipment) on Pavement Performance
Agricultural equipment causes considerable damage to rural roads poorly suited for such massive loads. Researchers used instrumented test sections to measure the impacts of various farm implements and found that increasing axles on equipment and driving in the middle of the road can dramatically reduce pavement damage.
Technical Summary: 201208TS (PDF 760 KB, 2 pp)
Final Report: 201208 (PDF 13 MB, 551)
Rolling Resistance Measurements at the MnROAD Facility
Project researchers from the University of Gdansk, Poland, and Minnesota State University, Mankato, obtained and analyzed rolling resistance data for Cells 7, 8, and 9 of the MnROAD mainline. They also conducted a comparison of the rolling resistance to surface texture, friction, and noise.
Final Report: 201207 (PDF 3.4 MB, 60 pp)
Vehicle Speed Impacts of Occasional Hazard (Playground) Warning Signs
This research project evaluated whether installing playground warning signs near three parks in Bloomington affected vehicle speeds. Researchers found that the signs had very little impact, but that drivers did slow down when playgrounds were busy and when there were many cars parked along the street.
Technical Summary: 201206TS (PDF 554 MB, 2 pp)
Final Report: 201206 (PDF 1.1 MB, 78 pp)
Using Twin Cities Destinations and Their Accessibility as a Multimodal Planning Tool:
Task 5 Report
Researchers evaluated how accessibility in the Twin Cities region would be affected by various changes in land use (including population and employment scenarios) and the transportation network (due to proposed highway infrastructure improvements and public transit investments). Results showed that centralized growth in population and employment produced the highest accessibility, followed by centralized population and decentralized employment. However, because of increasingly decentralized population and employment along with the infeasibility of a free-flowing highway network, investments in congestion pricing and high occupancy toll lanes may be the best strategies for maximizing accessibility.
Technical Summary: 201205TS (PDF)
Final Report: 201205 (PDF 143 MB, 767 pp)
Development of Freeway Operational Strategies with IRIS-in- Loop Simulation
Developing efficient and robust traffic control strategies that can directly be implemented in the existing operational environment is of critical importance in improving the effectiveness of freeway management. Currently the freeway network in the Twin Cites is being managed with the Intelligent Road Information System (IRIS), a computerized operating system developed by MnDOT to control the field devices such as ramp meters, variable message signs and loop detectors. This research develops a comprehensive support and development tool for IRIS by integrating it with a microscopic traffic simulator. The resulting IRIS-In-Loop simulation system (ILSS) can be used to emulate and refine various types of freeway operational strategies prior to field implementation. As a first application of ILSS, an alternative ramp metering strategy will be developed in this research and evaluated with ILSS. Further, a computerized process will be developed to estimate a set of traffic condition measures for given freeway corridors with selected time periods. The quantified measures can be used to support different levels of decision making process at MnDOT in planning and operating the freeway network.
Technical Summary: 201204TS (PDF 761 KB, 2 pp)
Final Report: 201204 (PDF 2.4MB, 79 pp)
Evaluating the Cost and Benefits of Living Snow Fences
Researchers developed a calculator for estimating Living Snow Fences program payments to landowners by identifying costs, benefits and obstacles to implementing the program, including landowner costs and constraints, agency constraints and potential agency benefits from avoided carbon emissions and avoided snow removal and safety costs. Recommendations include offering shorter and more flexible LSF contracts, increasing compensation at key locations, adjusting payments for inflation, tying payments to corn and land prices, increasing payments in the first three years to offset maintenance, reducing risk and landowner liability, compensating for replanting and increasing awareness. By contracting 40 percent of sites with snow problems to LSF, MnDOT could save $1.3 million per year.
Technical Summary: 201203TS (PDF 463 KB, 2 pp)
Final Report: 201203 (PDF 3.8 MB, 174 pp)
Using Computer Modeling to Improve the Design of Unbonded Concrete Overlays
Researchers evaluated existing design procedures for unbonded concrete overlays, including MnDOT guidelines, by analyzing UBCO crack propagation using a computer model that relates the load capacity of a pavement to its dimensions and material properties, including fracture energy. Results suggest that this model shows promise for improving UBCO design by determining the load capacity of a new single-layer portland cement concrete pavement designed using current procedures, and then determining thickness and material properties for a UBCO that will yield the same load capacity.
Technical Summary: 201202TS (PDF 397 KB, 2 pp)
Final Report: 201202 (PDF 1.9 MB, 79 pp)
Best Value Granular Material for Road Foundations
Researchers evaluated how mechanistic-empirical design procedures can be used to make effective use of local Minnesota aggregates in the unbound pavement layers of flexible pavements by determining how aggregate properties such as angularity and surface texture affect aggregate quality as measured by resilient modulus and shear strength. Results showed that aggregate angularity and surface texture were more important to determining the resilient modulus of aggregates than gradation alone, and that use of locally available materials can be cost-effective for low-volume roads with 20-year design traffic level and no more than 1.5 million equivalent single-axle loads.
Technical Summary: 201201TS (PDF, 794 KB, 42 pp)
Final Report: 201201 (PDF 6.4 MB, 167 pp)
Putting Research into Practice: Traffic Generating Development and Roadway Life Consumption
The Traffic Generators calculation tool for estimating pavement impacts, developed as part of this project, is a spreadsheet based tool that takes user input from the agency as well as the developer, and combines this information into an estimate of pavement damage. This is done in three ways – difference in granular equivalent pavement design, MnDOT overlay design, and percent of pavement life consumed. With guidance in this report, the agency can select which of the three methods is most appropriate for their particular situation. The tool then provides an estimate of cost required to repair the roadway network to its condition prior to the heavy influx of construction traffic.
Final Report: 2012RIC11 (PDF 2.25 MB, 40 pp)
Pooling Our Research: Urban Mobility Study
The study focuses on developing tools to monitor and evaluate urban congestion by identifying and evaluating the latest mobility data sources, developing and communicating comprehensive performance measures for congestion improvements and helping member agencies apply the study's research products to their congestion planning.This Urban Mobility Study is nationally recognized as the leading resource for traffic congestion research.
Technical Summary: 2012TPF-5(198) (PDF 503 KB, 2 pp)
Pooling Our Research: Using Recycled Shingles in Asphalt Pavements
Researchers conducted a literature review of nationwide applications of manufactured and tear-off shingles, focusing on specifications, case studies, demonstration projects and environmental safety. Member states involved in this study have developed quality control and assurance procedures for sourcing and processing RAS, and have conducted their own demonstration projects for both post-manufactured and post-consumer RAS to develop mix design criteria and construction specifications. These specifications generally allow up to 5 percent post-manufactured RAS in HMA when used with RAP, and also set the required percentage of virgin binder and place limits on the percentage of allowable deleterious content.
As part of this pooled fund study, MnDOT evaluated MnROAD test sections using post-manufactured and post-consumer RAS. Researchers conducted laboratory and field tests to evaluate the effects of binder grade and content as well as RAP or RAS source and content on the performance of HMA mixtures, especially on low-temperature cracking and stripping. Results published in the 2010 report "Incorporation of Recycled Asphalt Shingles in Hot-Mixed Asphalt Pavement Mixtures" confirmed MnDOT specifications requiring at least 70 percent new asphalt binder and led to provisional specifications allowing for the use of up to 5 percent post-manufactured and post-consumer RAS in both surface and base mixes for plant-produced asphalt mixtures under Specification 2360.
Technical Summary: 2012TPF-5(213) (PDF 877 KB, 2 pp)
Pooling Our Research: Improving Winter Maintenance with New Technologies
As state DOTs aggressively pursue new technologies and practices for improving winter highway operations, Clear Roads supports their evaluation in both the laboratory and the field to develop industry standards, performance measures and cost-benefit analyses, practical field guides and training curricula. The scope of the effort is currently expanding to focus on state agency needs, technology transfer and implementation, including support for staff in the field.
Technical Summary: 2012TPF-5(218) (PDF 730 KB, 2 pp)
Pooling Our Research: The Transportation Engineering and Road Research Alliance
To broaden MnROAD's unique capabilities and to make it a regional, national and international resource, in 2004 MnDOT spearheaded the development of the Transportation Engineering and Road Research Alliance (TERRA). TERRA is a collaboration of MnDOT and several other states that brings together government, industry and academia in a dynamic partnership to advance innovations in road engineering and construction.
Technical Summary: 2012TPF-5(215) (PDF, 516 KB, 2 pages)
2013 | 2012 | 2011 | 2010 | 2009 | 2008 | 2007 | 2006 | 2005