01 - practical guide torrailway engineering.pdf

Chapter Abstracts Introduction: The authors of the "Practical Guide To Railway Engineering" wish to provide the reader a general overview of the specific disciplines common to railway engineering. Railway engineering design requires that the engineer approach any modern engineering challenge with an understanding that encompasses the railway as a system; thereby requiring the practicing engineer have a general understanding of disciplines other than just their own. The text hereafter is not intended to supplant the AREMA Manual for Railway Engineering, the AREMA C&S Manual or other comprehensive texts covering specific railway engineering disciplines, but rather to provide background enabling the novice engineer or practicing engineer unfamiliar with railway engineering design to utilize available resources. Each author and contributor shares a deep love for the industry, and it is their desire that the pool of collected information be passed on to the next generation of "railroader" as well. Chapter 1 Railway Development Chapter 1 provides a brief overview of the key occurrences in the history of transportation leading up to the introduction and implementation of railways and railway engineering in North America. The goal of this chapter is for the reader to obtain an appreciation for the reasons behind some of the key current railway engineering practices based on railway development history. The significant economic role played by innovations such as CWR, CTC, mechanization of maintenance activities, along with the evolution of bridge design, materials and construction practices is explored. Chapter 2 Railway Industry Overview Chapter 2 is designed so the reader will gain an understand of the organizational structure of a railway and to recognize the role played in railway operations by safety, operating rules, authority of movements, speeds and traffic control systems. Critical issues affecting railway traffic systems are also considered. Various car configurations and related usage are identified along with factors governing locomotive utilization including: horsepower and tractive effort tractive force and adhesion drawbar pull train resistance compensated grades

acceleration and balance speeds tonnage ratings ruling grade momentum grade power to stop

Chapter 3 Basic Track Chapter 3 is written for the reader to become more familiar with track components and terminology and includes over 100 illustrations. The reader will understand the criteria used to justify maintenance operations and/or capital improvement as well as recognize

the role of track geometry in maintaining and operating today's railway. Specific maintenance activities along with the function of major production gang activities are discussed. The role of safety and safety enforcement is also addressed here. Chapter 4 Right-of-Way and Roadway Chapter 4 seeks to explain how right of way is defined and utilized. This chapter includes typical dimensions, property rights, limitations, utility easements, fencing, and vegetation. Also addressed are issues concerning; basic soil types, geotechnical behavior of various types of soils, typical track structure and the loading it imposes on the subgrade, roadbed failure (landslides and track settlement) causes and remediation, and ways to identify potential hazards to the roadbed and take appropriate action to mitigate those hazards. Chapter 5 Drainage Chapter 5 stresses the importance of drainage in maintaining quality track. The primary hydrology and hydraulic principles are reviewed along with a demonstration of the use of commonly available resources. Consideration is provided to the impact poor drainage design can have on railway neighbors as well as the integrity of the railway itself. Chapter 6 Railway Track Design Chapter 6 provides information pertaining to the different design elements of railway alignments, layout and design. Specific topics include horizontal and vertical alignment design, turnout geometry, location, and use; railway clearances and vehicular envelope requirements; typical yard and terminal functions and layouts. Additional considerations pertaining specifically to design elements of railway alignments and limitations are discussed as they relate to proposed use (i.e. mainline, branch line, industrial/terminal, and passenger). Chapter 7 Communications and Signals Chapter 7 is intended as a basic overview of railway signaling. The chapter provides an appreciation of the historical development of railway signal systems as well as an understanding of basic signal terminology. An easy to understand approach explains concepts such as ABS and CTC. Basic types of signals, available energy sources, lightning and surge protection and basic track circuits including: DC track circuits, Coded DC track circuits, Style C track circuits, Overlay track circuits and AC track circuits are addressed here. An understanding of track switches, components and their interconnection to the signal system is provided. Crossing warning device theory of operation and differences between conventional and solid state devices is highlighted. The basic principles of CTC, sequence of operation and safety checks are explained along with concepts associated with microprocessor based coded track circuits and solid-state interlockings. Finally, a description of the common types of defect detectors in use is provided.

Chapter 8 Railway Structures Chapter 8 was prepared to accomplish two primary objectives. For the novice engineer, the authors wished to provide an overview of the types of railway bridge structures and their appropriate usage as well as define the primary bridge components and their functions. Further, drainage structures, retaining walls, tunnels and sheds are classified by type as well as by common use. For the experienced highway design engineer, the common design approach differences between highway and railway bridges are reviewed. Discussion centers on the differences in design loading in Timber Chapter 7, Concrete Chapter 8 and Steel Chapter 15 of the AREMA Manual for Railway Engineering. Other critical structure criteria are highlighted such as fatigue, fracture critical members, structure serviceability, bearings and volumetric changes and composite design. Chapter 9 Railway Electrification Chapter 9 compares the various alternatives available when considering and designing an electrified railway. A general overview of the key components and their primary function is provided for 3rd rail systems and overhead catenary systems (OCS). Fundamental criteria for selection of style of OCS are discussed along with other design basics. Finally, the impact that implementation of electrification will have on existing railroad infrastructure, staff and community is discussed. Chapter 10 Passenger, Transit and High-Speed Rail Chapter10 presents an overview of typical design principles, construction practices and maintenance considerations applied to passenger rail lines. It describes how basic railroad engineering principles are applied in specialized ways to accommodate passenger rail requirements. The chapter notes the key distinctions between railroad and transit operations and introduces six major types of passenger rail modes. The text then discusses the service, infrastructure, regulatory (U.S.), maintenance and inspection considerations associated with each. It concludes with discussion of the special topics of line capacity and cant deficiency. Chapter 11 - Environmental Regulations And Permitting Chapter 11 is a general overview of environmental regulations and permitting in the U.S., Canada and Mexico with topics that may be encountered during railway activities (including construction, as well as operation). This information is general in nature and the reader is cautioned to contact or use a professional environmental consultant to prepare an Environmental Assessment. Information is given on wetland issues along with other topics, such as endangered species, cultural resources, Phase I environmental assessments, hazardous waste, brownfields, asbestos and air quality. Environmental information includes: the U.S. Army Corps of Engineers wetland definition, Nationwide and General permits for proposed construction activities, U.S. Army Corps of Engineers non-jurisdictional status over isolated wetlands and Best Management Practices (which

mitigate direct and indirect degradation of the environment to the extent possible). Each topic concludes on where to locate additional information. Chapter 12 European Curve & Turnout Mechanics Chapter 12 serves to provide an appreciation of the European approach design differences in turnout and curve design from that experienced in North America. The reader will obtain an understanding of the geometrical and mathematical relationships common to both North American and European track geometry. The potential for incorporating European practices in high-speed North American transit initiatives is clearly obvious. Chapter 13 Case Studies Chapter 13 presents four case studies drawn from actual railway design projects using formatted templates to identify critical stakeholders, identify controlling criteria, recognize potential problems, and learn from past mistakes. These case studies are intended to serve as a model for which the templates can be utilized for any railway design/construction project. It is intended that this will be part of an accessible library of case study solutions yet to be developed. Appendix The Appendix contains a wide variety of useful and related information to the material presented in the text. Included are articles describing the development of maintenance-of-way practices in the past 40 years from the perspective of a retired Class 1 chief engineer, geometry solutions for turnout and connection track location, spiral and full body curve example problem solutions, Bartlett Method of calculating throws for stringlining curves and a synopsis of one Class 1 railways step by step procedures for performing common maintenance and capital improvement activities. Glossary The glossary contains short definitions of the majority of the terms utilized within the text. Railway engineering terminology common to the industry is often not self-explanatory. It is essential that the engineer have a clear understanding of the terms in use.

TABLE OF CONTENTS_______________________________________________________________________

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Table of Contents Introduction 1 Chapter 1 - Railway Development 5

1.1 Introduction 7 1.2 Determinants of Transportation Development 9 1.3 Pre-Railway Transportation in North America 10 1.4 Physical Determinants of Land Movement 12 1.5 North American Railway Development and Impacts 15 1.6 Developments of the Twentieth Century 19 1.7 Development of Canadian Railways 21 1.8 Mexican Railway Development 23 1.9 Institutional Controls 24 1.10 History of Railway Bridge Engineering 25 1.11 New Technology Bridge Developments in the Last Twenty Years 27

1.11.1 Existing Railway Bridges: Inspection and Assessment 27 1.11.2 New Railway Bridges: Materials, Design, Fabrication and Construction 28

1.12 Trade Journals 29 1.13 Other References 30

Chapter 2 - Railway Industry Overview 31

2.1 Introduction 33 2.2 Railway Companies 33

2.2.1 Organization of a Railway Company 34 Transportation Department 35 Engineering Department 36 Mechanical Department 37 Marketing Department 37

2.3 Regulatory Agencies and Railway Associations 38 2.3.1 Regulatory Agencies 38

United States 38 Canada 39

2.3.2 Railroad Associations 39 AAR and RAC 39 AREMA 40 REMSA 40 RSSI 40

2.4 Operations of Railways 41 2.4.1 Safety First in Railway Operations 41 2.4.2 Bibles of the Railways for Safe Operations 42 2.4.3 Tracks and Authority of Movements 43 2.4.4 Speeds 45 2.4.5 Rail Traffic Control Systems 46

Radio Communication of Train Orders 46 Train Spacing and Block Separation 46 Track Circuit 47 Signal Block Length 47 Centralized Traffic Control 48 Additional Information 49

2-5 Railway Cars 49 2.5.1 Freight Cars 49

Boxcars 50 Insulated Boxcars and Mechanical Reefers 50 Intermodal Cars Piggyback Trailers and Containers 50 Flat Cars 51 Auto Rack Cars 52 Gondola Cars 52 Hopper Cars 52 Rotary Gondola/Hopper Cars 52 Tank Cars 52 Maintenance-of-Way Cars 53 Schnabel Cars 53

2.5.2 Hazardous Commodities 53 2.5.3 Passenger Cars 53

2.6 Locomotives 54 2.6.1 Horsepower (hp) and Tractive Effort 55 2.6.2 Tractive Force and Adhesion 55


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2.6.3 Drawbar Pull 56 2.6.4 Train Resistance 56

Rolling Resistance 56 Davis Formula 57 Starting Resistance 57 Grade Resistance 58 Curve Resistance 58

2.6.5 Compensated Grade 58 2.6.6 Acceleration and Balance Speed 59 2.6.7 Tonnage Ratings of Locomotives 60 2.6.8 Ruling Grade 60 2.6.9 Momentum Grade 60 2.6.10 Power to Stop 61

2.7 Traffic Systems 62 2.7.1 Priority of Trains 63 2.7.2 Effects Of Sharing Tracks By Freight And Passenger Trains Vs. Track Of Single Use 64 2.7.3 Overcoming The Delays That Occur In Freight Yards 65

Chapter 3 - Basic Track 67

3.1 Track Components 69 3.1.1 Rail 69

Identification of Rail 70 3.1.2 Ties 72

Timber Ties 72 Concrete Ties 75 Steel Ties 75 Alternative Material Ties 76

3.1.3 Ballast Section 76 3.1.4 Rail Joints 78

Standard Joints 79 Compromise Joints 79 Insulated Joints 80

3.1.5 Tie Plates 82 3.1.6 Rail Anchors 83 3.1.7 Fasteners 83

Spikes 84 Bolts 85

3.1.8 Specialized components 85 Derails 86 Wheel Stops and Bumping Posts 86 Gauge rods 87 Sliding (Conley) Joints 87 Mitre Rail 87 Bridge/tunnel/overpass guard rails 88

3.2 Turnouts 88 3.2.1 Types of Turnouts 88

Basic Turnout Terminology 89 3.2.2 Switch 90 3.2.3 Switching Mechanism 91 3.2.4 Turnout Rails 91 3.2.5 Frog 92

Rail bound manganese (RBM) 92 Spring Frog 93 Solid Manganese Self-guarded Frog 93 Bolted Rigid Frogs 94 Movable Point Frogs 94 Determining Frog Number 94

3.2.6 Switch Ties 95 3.2.7 Stock Rails 95 3.2.8 Switch Points 96

Identifying Left or Right Hand Points 97 3.2.9 Specialty Components 97

Switch Clips 97 Switch Rods 97 Types of Switch Rods 98 Connecting Rod 98


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3.2.10 Special Turnout Plates 99 Gauge Plates 99 Switch Plates 100 Rail Braces 100 Heel Block Assembly 101 Turnout Plates 101 Hook Twin Tie Plates 101 Frog Plates 102

3.2.11 Guard Rails 102 3.2.12 Switch Stands 103

Spring Switch 103 3.3 Railway Crossings & Crossovers 104 3.4 Highway Crossings 106

3.4.1 Crossing Construction And Reconstruction 108 3.4.2 Crossing Warning Devices 110

3.5 Utility Crossings 111 3.6 Track Geometry 112

3.6.1 Gage 114 3.6.2 Alignment 115

Full Body of the Curve 116 Transition Spiral of the Curve 117 Curve Elevation 117

3.6.3 Surface 118 3.7 Safety 120 3-8 Maintenance Activities 122

3.8.1 Track Disturbance 124 3.8.2 Track Disturbance Activities 125 3.8.3 Rail Lubrication 126 3.8.4 Rail Grinding 127 3.8.5 Rail Defect Testing 128 3.8.6 Geometry Cars 128 3.8.7 Gauge Restraint Measuring System (GRMS) 129 3.8.8 Vegetation Control 129 3.8.9 ROW Stabilization & Drainage 131 3.8.10 Welding 132

3-9 Production Gangs 133 3.9.1 Production Rail Gang 134 3.9.2 Production Tie Gang 136 3.9.3 Production Undercutting 138 3.9.4 Production Surfacing Gangs 139 3.9.5 Road Crossing Renewal Gangs 142 3.9.6 Turnout Renewal 143 3.9.7 New Track Construction/Cutout New Track Construction /Cutovers 144

References: 147 Chapter 4 - Right-of-Way & Roadway 149

4.1 Introduction 151 4.2 Right-of-Way 152

4.2.1 Right-of-Way Width 152 4.2.2 Fences 153 4.2.3 Utilities 154 4.2.4 Vegetation 154

4.3 Roadway 155 4.3.1 Soils 155

Definition 155 Soil Types 157 Major Soil Divisions 157 Soil Texture and Composition 160

4.3.2 Geotechnical Processes 161 The Concept of Stress and Strain 161 Effective Stress 162 The Effect of Porewater Pressure 162 Clays 163 Sand and Gravel 163 Silt 164 Soil Behavior Under Rapid Loading 164 Effect of Shear Strain 164 Settlement 165 Seepage 166


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4.3.3 Track Structure 167 Historical Background 167 Components and Functions 168 Subgrade 169 Sub-ballast 170 How Track Fails 170

4.3.4 Instability 172 Main Features of Landslides 172 Slides that Affect the Track 172 Triggering Mechanisms 174 Remediation 175 Soil Improvement 176 Improved Slope Geometry 176 Reduce Seepage Pressure 178 Structural Support 179 Inspection of Slopes 180 Monitoring Slope Movements 180 Areas With the Greatest Hazard 181

4.3.5 Settlement 182 Basic Theory 182 Influence of Construction Methods 183 Influence of Soil Type 183

4.3.6 Hazard Identification 184 Understanding the Factors 184 Understanding the Mechanisms 185 Identifying the Hazard 185

4.3.7 Summary 185 Chapter 5 Drainage 189

5.1 Hydrology 191 5.1.1 Equations and Programs 192 5.1.2 Rainfall Intensity or Precipitation 194 5.1.2 Rainfall Intensity or Precipitation 195 5.1.3 Time of Concentration 197 5.1.4 Distribution 198

5.2 Hydraulics 198 5.2.1 Open Channel Hydraulics 198 5.2.2 Culvert Hydraulics 202

5.3 Recommended Procedures 210 5.3.1 Existing Drainage Study 210 5.3.2 Proposed Drainage System 211 5.3.3 Floodplain Encroachment Evaluation 212 5.3.4 Erosion Control Evaluation 213

Chapter 6 - Railway Track Design 216

6.1 Stationing 218 6.2 Horizontal Alignments 219

Staking Spirals By Deflections 227 Staking Spirals By Offsets 228 Applying The Spiral To Compound Curves (Arema 1965) 228

6.3 Vertical Alignments 229 6.4 Alignment Design 232 6.5 Turnouts 244 6.6 Design Of Yards 253 6.7 Clearances 256 References: 262

Chapter 7 - Communications & Signal 263

7.1 Introduction to Signals 265 7.1.1 Railway Operation 265 7.1.2 Timetable Operation 266 7.1.3 Wayside Signals 268 7.1.4 Color Light Signal 269 7.1.5 Signal Terminology 269 7.1.6 Searchlight Signal 270 7.1.7 Operating Principle 270 7.1.8 Automatic Block Signals 271 7.1.9 Signal Location 272 7.1.10 Common Terms 273 7.1.11 Automatic Block Signal System 274


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7.1.12 Centralized Traffic Control (CTC) 275 7.2 Energy Source 275

7.2.1 Batteries 275 7.2.2 Battery Charging 276 7.2.3 Lightning Protection 278

7.3 Track Circuits 279 7.3.1 DC Track Circuits 279 7.3.2 Track Circuit Operation 280 7.3.3 Train Shunting 282 7.3.4 Coded DC Track Circuit 283 7.3.5 Style C Track Circuit 286 7.3.6 Overlay Track Circuits 287 7.3.7 Overlay Track Circuit Operation 288 7.3.8 Track Coupling Unit 288 7.3.9 AC Track Circuits and Relays 289 7.3.10 Apparatus Used with AC Track Circuits 290

7.4 Track Switches 291 7.4.1 Hand Operated Switch with SCC 291 7.4.2 Electric Switch Lock 293 7.4.3 Dual Controlled Power Switch Machine 294

7.5 Highway Crossings 297 7.5.1 Crossing Operation 298 7.5.2 Crossing Gates 299 7.5.3 Crossing Motion Detector/Predictor 300

7.6 Centralized Traffic Control (CTC) 302 7.6.1 Operation 302 7.6.2 Sequence of Operation 305 7.6.3 Microprocessor Based Coded Track Circuits 308 7.6.4 Theory of Coded Track Circuit Operation 309 7.6.5 Solid State Interlocking 311

7.7 Defect Detectors 313 7.7.1 Hot Box Detector 313 7.7.2 Hot Wheel Detector 313 7.7.3 Dragging Equipment Detector 313 7.7.4 Wheel Defect Detector 314 7.7.5 Slide Fence 315 7.7.6 Flood Detectors 316 7.7.7 Fire Detectors 316 7.7.8 High/Wide Load Detectors 316

Chapter 8 - Railway Structures 318

8.1 Introduction to Railway Structures 320 8.2 Major Bridge Components 321

8.2.1 Substructure 322 Investigate Underlying Soil & Geologic Conditions 322 Piling 322 Abutments and Piers 327

8.2.2 Superstructure 329 8.2.3 Bridge Deck 330

Open Bridge Decks 331 Ballasted Decks 333 Open Deck Vs. Ballast Deck 335

8.3 Bridge Types 337 8.3.1 Timber Trestles 337

Terminology 337 Caps 339 Stringers 339 Timber Connectors 340

8.3.2 Steel Bridges 340 Girder Spans 340 Truss Spans 342 Steel Trestles 345 Viaducts 345

8.3.3 Concrete Bridges 346 Arches 346 Rigid-Frame Bridge 346 Slab Bridges 347 Concrete Trestles 347 Concrete Girders 348


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8.3.4 Moveable Spans 349 Bascule Bridges 349 Swing Span Bridges 351 Vertical Lift Bridges 352

8.4 Other Structures 355 8.4.1 Drainage Structures 355 8.4.2 Retaining Walls 356

Gravity Retaining Walls 356 Crib Walls 356 Sheet Piling 358 Mechanically Stabilized Earth 359 Drainage of Retaining Walls 360

8.4.3 Tunnels 361 Tunnel Construction Methods 361

8.4.4 Sheds 364 8.5 Structural Design Considerations 365

8.5.1 Introduction 365 8.5.2 Bridge Loading, 366

Dead Load 366 Live Loads 367 Impact 370 Centrifugal Load 372 Lateral Loads 374 Longitudinal Loading 375 Wind Loading 377 Stream Flow, Ice and Buoyancy 378 Seismic Loads 379 Combined Loads 381

8.5.3 Other Structure Design Criteria 381 Fatigue 381 Fracture Critical Members (FCM) 382 Structure Serviceability 383 Bearings and Volumetric Changes 385 Composite Design 387 Bridge Design Assumptions and Constructibility Issues 388 Recommended Construction Considerations 389

8.5.4 Retaining Wall Loads 391 References: 392

Chapter 9 - Railway Electrification 393

9.1 Introduction 395 9.2 Development of Motive Power for Railways 395

9.2.1 Pioneers of Electric Traction Development 398 9.3 Rail Operation Classification 401 9.4 Mainline Railways and Independent Short Lines 403

9.4.1 Mainline Electrification Studies 404 9.4.2 Mainline Infrastructure Compatibility 406

Maintenance 408 Staff Safety 408

9.4.3 Impacts of Mainline Railway Electrification on Communities. 409 9.5 Urban Railways 409

9.5.1 Impacts of an Urban Electrified Light Rail or Commuter Rail System on the Community 410 9.6 Existing Electrification Systems 411 9.7 New Electrification Systems 414

9.7.1 Sources of Primary Power 415 9.7.2 Substations 415 9.7.3 Power Distribution Systems 417

Feeder Cable Sub Systems 417 Negative Feeder Cable Sub Systems 418 Contact System Sub Systems 418

9.7.4 Current Collectors 419 Contact Shoe 419 Trolley Poles 420 Pantographs 420

9.7.5 Characteristics Of Third Rail System 421 Conductor Rail Supports 421

9.7.6 Characteristics Of An Overhead Contact System 422 Single Wire System 423 Catenary Systems 425


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9.7.7 OCS Style Selection 428 Location and Environment 429 Copper Cross-sectional Area 429 Economics 430 Cost Factors of OCS Styles 433 OCS Design Basics 433

9.8 Electrification Interfaces with Other Rail Elements 434 9.8.1 Right-of-Way 434

Track Layout/Realignment 434 Substations 435 Supporting Structures for the Contact System 435 Systemwide Ductbanks 435

9.8.2 Track Structure 435 9.8.3 Civil Structures 436

Tunnels To Be Electrified 436 Bridges Over Electrified Track 437 Bridges Under Electrified Track 437 Station Canopies 437 OCS Attachments 437

9.8.4 Signals and Communications 438 9.9 Interfaces with Project-Wide Staff 439 Bibliography 443

Chapter 10 - Passenger, Transit & High Speed Rail 445

10.1 Introduction 447 10.2 Passenger Rail Modes 448 10.3 Distinctions between Railway Operations and Transit Operations 449 10.4 Passenger Rail Service and Vehicle Characteristics by Mode 450 10.5 Passenger Rail Infrastructure Characteristics by Mode 451 10.6 Passenger Railway Infrastructure Characteristics 453

10.6.1 High-Speed Rail (HSR) 453 Route Alignment Considerations 453 Regulatory Compliance 454

10.6.2 Intercity Rail and Commuter Rail 455 General 455 Route Alignment Considerations 455 Track Standards 455 Regulatory Compliance 456

10.7 Transit Infrastructure Characteristics 457 10.7.1 Rapid Transit 457

Route Alignment Considerations 457 Track Standards 457 Regulatory Compliance 459

10.7.2 Light Rail Transit (LRT) 459 Route Alignment Considerations 459 Track Standards 459 Regulatory Compliance 461

10.7.3 Streetcar and Vintage Trolley 461 Route Alignment Considerations 461 Track Standards 461 Regulatory Compliance 461

10.8 Passenger Railway Maintenance Considerations 462 Maintenance Philosophy 462 Maintenance Practices 462

10.9 Transit Maintenance Considerations 463 Maintenance Philosophy 463 Maintenance Practices 464

10.10 Special Topics Associated with Passenger Railway Operations 465 10.10.1 Passenger Railway Line Capacity 465 10.10.2 The Impact of Superelevation (Or Cant Deficiency and Why Its Important) 467

10.11 Conclusion 469 Chapter 11 - Environmental Conditions & Permitting 471

11.1 Introduction 473 11.2 Environmental Regulations Of The United States 473

11.2.1 Wetlands Regulations 474 U.S. Army Corps of Engineers Regulatory Boundaries 476

11.2.2 Wetland Definition 477


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11.2.3 Wetland Regulations 481 Nationwide Permits 481 General Permits 486 USACE Non-Jurisdiction Over Isolated Wetlands 487

11.2.4 Best Management Practices 488 11.2.5 Endangered Species 488 11.2.6 Cultural Resources 491 11.2.7 Phase I Environmental Assessment 492 11.2.8 Hazardous Waste 494 11.2.9 Brownfields 496 11.2.10 Asbestos 496 11.2.11 Air Quality 497

11.3 Environmental Regulations Of Canada 499 11.3.1 Canadian Wetlands Environmental Assessment Guidelines 500 11.3.2 Endangered Species 502 11.3.3 Hazardous Waste 503 11.3.4 Air Quality 504

11.4 Environmental Regulations Of Mexico 504 11.4.1 Regulations 505 11.4.2 Mexico Regulation for Hazardous Waste 506

11.5 Wetland Case Study 507 Chapter 12 - European Curve and Turnout Mechanics 511

12.1 Introduction 513 12.2 Curves 514

12.2.1 Curve Definition 514 12.2.2 Gage 515 12.2.3 Elevation in Curves 517 12.2.4 Elevation Transition 518 12.2.5 Track Warp 523 12.2.6 Horizontal Transition Curves 524 12.2.7 Theory of the Transitional Curves 526

12.3 Gradient Change 529 12.4 Turnouts and Turnout Design 531

12.4.1 Measuring the Frog Angle 533 12.4.2 Turnout Calculations 534 12.4.3 Clothoidal Turnout 537

12.5 Speed Raising Improvements 540 12.5.1 Curve Improvements 542 12.5.2 Surfacing and Lining 543

Chapter 13 - Case Studies 547

13.1 Introduction 549 #1 Kasky, KY Project Survey 551 #2 Crestline, OH Project Survey 557 #3 FEC/SFRC Connection, West Palm Beach, FL For Amtrak Service Project Survey 561 #4 - Ft. Washington PA Project Survey 567

Appendix A-1

Applied Science For Railway Tracks A-3 Turnouts, Connections, And Crossings B-1

Turnouts B-1 Location of Turnouts B-1 Turnouts from Straight Track B-2 Turnouts from Curved Track B-3

Connections B-3 From Straight Track B-3 Turnout from the Inside of a Curved Main Track B-5 Turnout from the Outside of a Curved Main - Track B-12

Parallel Tracks - Sidings B-17 Parallel Tracks Both Straight Tracks B-17 Parallel Tracks - Curved Tracks B-18

Parallel Tracks - Crossovers B-22 Crossovers - Straight Tracks. B-23 Crossovers - Curved Tracks B-24

Ladder Tracks B-25 Intersecting Tracks B-27

Intersecting Tracks - Both Tracks Straight B-27 Intersecting Tracks - One Straight and One Curved Track B-31 Intersecting Tracks - Both Tracks Curved B-34


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Wye Tracks B-35 Wye Track - Straight Main Track B-36 Wye Track - Curved Main Track B-37 Diamond Turnouts B-38

Crossings B-39 Crossing Data B-40 Straight Crossings B-41 Single-Curve Crossings B-42 Double-Curve Crossings B-43

Example Curve Problems With Solutions C-1 PROBLEM 1. C-1 PROBLEM 2. C-1 PROBLEM 3. C-1 PROBLEM 4. C-2 PROBLEM 5. C-2 PROBLEM 6. C-3 PROBLEM 7. C-4 PROBLEM 8. C-8 PROBLEM 9. C-9 PROBLEM 10. C-13 PROBLEM 11. C-18

Spiral Problems & Solutions D-1 Determining Degree Of Curvature E-1 Method Of Determining Degree Of Curvatue E-2 String Lining Curves F-1 Stringlining Of Railroad Curves G-1 Maintenance Processes H-1

Ballast Unloading H-3 Gauging on Wood and Concrete Ties H-7 Mechanical Surfacing of Track H-11 Switch Tie, Yard and Siding Ties & Programmed Maintenance Tie Renewal H-17 Rail Train Rail Pickup H-22 CWR Rail Relay on Wood or Concrete Ties H-27 Mechanized Tie Renewal H-32 Track Abandonment H-37 Track Sledding H-44 Installation of Panelized Turnouts H-50 Unloading Continuous Welded Rail (CWR) H-57

GLOSSARY Glossary-1

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1.1 Introduction

History Ring Out, oh bells. Let cannons roar In loudest tones of thunder The iron bars from shore to shore Are laid and Nations wonder

his quote from the May 11, 1869 The Chicago Tribune celebrated the completion in Utah of the first transcontinental railway connection in North America. By 1885 the Canadian Pacific completed the first single company

transcontinental line and the Atlantic and Pacific were also first linked in Mexico in the 19th century. The exciting impact of a technology that reduced a six-month to a six-day trip can hardly be imagined today. In the lifetime of anyone reading this, we have seen nothing with the impact on all aspects of life as the development of the railway.

Only 44 years earlier on October 27, 1825 George Stephensons steam locomotive, Locomotion Number 1 hauled a 90 ton load consisting of 36 cars carrying more than 500 passengers and some freight at a sustained speed of 12 mph along the Stockton and Darlington Railway in northern England. This was the culmination of decades of imagination, promotion, engineering and experimentation.

What is a railway? A railway can be defined as an engineered structure consisting of two metal guiding rails on which cars are self-propelled or pulled by a locomotive. In his book John Armstrong defines a railway as:

A railroad consists of two steel rails which are held a fixed distance apart on a roadbed. Vehicles, guided and supported by flanged steel wheels and connected into trains, are propelled as a means of transportation. Websters Dictionary (1986) defines a railroad as 1. A road laid with parallel steel rails, along which cars carrying

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passengers or freight are drawn by locomotives, 2. A complete system of such roads, including land, rolling stock, stations, etc. 3. The persons or corporation owning and managing such a system.

The terms railway and railroad are sometimes used interchangeably. However, for this book, railway will generally refer to the track and other closely associated items, i.e., signals, crossings, bridges, etc. Railroad will be used where the usage connotes the bigger system.

In commencing a railway engineering career, you are joining many fellow workers in a complex and increasingly coordinated activity that is an integral part of any civilized society. About one-seventh of the workers in advanced economies are involved in some phase of transportation. Transportation, the movement of persons and goods, of which railroading is a large and vital part, is tied in with the location and magnitude of all kinds of human activity which depend on the timely availability of quality goods and services. This ranges from the necessities of food and fuel and work to leisure pursuits.

Many of you will be considered as transportation engineers specializing in railway engineering (not operating trains). We can define railway engineering as that branch of civil engineering involved in the planning, design, construction, operation and maintenance of railway land facilities used for the movement of people and goods serving the social and economic needs of contemporary society and its successors. The complete railway engineer is active in all aspects of civil engineering practice, surveying, geotechnics, hydrology, hydraulics, environmental and sanitary and structural design as well as construction technology.

You will frequently encounter the word mode in your railway practice. A mode of transportation is no more than a particular type of transportation defined in enough detail for the purpose at hand. It can be as general as the medium through or on which transportation takes place; for example, air, sea and land modes. The walking or pedestrian mode involves the moving human. The public transportation mode includes those systems such as rail commuter lines and public bus and taxi service. Often, far more detailed descriptions are needed for effective analysis, communication and understanding. The railway mode is a type of a land transportation mode as defined above. The light rail transit mode is a further more specifically defined type of rail service, typically today an urban, electrically powered system operating on its own right of way with intersections with intersecting public streets. Other terms used in railway engineering are listed and defined in the Glossary found at the end of this Manual.

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Figure 1-5 English Railways and Freight Cars, as Illustrated in Stricklands Report, 1826

Railways quickly became a major factor in accelerating the great westward expansion, as well as tying the older eastern population and industrial centers together, by providing a reliable, economic and rapid means of transportation. As additional lines were built, they facilitated the establishment and growth of towns in the West. Except for the trip from farm to railhead in town, the poor roads and limited canals became irrelevant. The Federal government and states encouraged and provided financial support through land grants and loans, which were paid back with reduced rates for half a century.

Since the first railways, there have been many improvements in all aspects of railroading. For example, the development of the iron flanged T rail was achieved by 1840. (See Figure 1-8 for an early track section) Until mass steel making was developed, there was a continuing controversy between the use of malleable iron vs. cast iron for rail. By 1840 wooden ties kept in place by ballast stone had replaced simple stone surface support.

Haunch

Grooved

Flange Out

Ringwalt

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Railway Industry Overview

2.1 Introduction he railway industry encompasses not only the operating railway companies and transit authorities, but also the various government regulatory agencies, railway associations, professional organizations, manufacturers and suppliers of

locomotives, railcars, maintenance work equipment and track materials, consultants, contractors, educational institutes and, most important of all, the shipping customers.

The information in this chapter is of a general nature and may be considered as typical of the industry. However, each railway company is unique and as such it must be understood what is included in this chapter may not be correct for a particular company.

2.2 Railway Companies Government owned freight railways are nowadays limited to some regional lines where transportation service must be protected for the economic well being of the communities. Passenger railways, on the other hand, are generally owned by governments. Transcontinental services, such as the Amtrak or VIA Rail in Canada, are corporations solely owned by the respective Federal Governments. These passenger railway companies normally do not own the trackage infrastructures. Except for certain connecting routes and dedicated high-speed corridors, they merely operate the passenger equipment on existing tracks owned by freight railways. Local rapid transit systems are usually operated as public utilities by the individual municipalities or transit authorities on their own trackage. Commuter services may be operated by government agencies or private sector on either their own or other railway owned trackage.

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The tractive effort (in pounds) available from a locomotive can be roughly calculated as:

Tractive Effort (lbs.) = Horsepower X (308) Speed (mph)

Where 308 is 82% of 375 lb-miles per hour per hp. For example, a 3000 hp locomotive will have approximately 74,000 lbs. tractive effort at 12.5 mph.

2.6.2 Tractive Force and Adhesion It is the tractive force at the locomotive driving wheels (drivers) at the rail that starts and moves tonnage up various grades. The maximum tractive force that can be developed at the rail is equal to the weight on drivers multiplied by the adhesion (coefficient of friction) of the wheels on the rail.

The primary factors, among others, affecting adhesion are rail condition and speed. Adhesion decreases as speed increases. At about 10 mph, adhesion varies from less than 10% on slimy, wet rail to about 40% on dry, sanded rail. In general, with the aid of the sanders, approximately 25% adhesion is usually available.

As all the wheels on most diesel locomotives are driving wheels, the weight of the locomotives must be about four times the tractive force developed. The HHP (high horsepower) units for main line service weigh about 195 tons each on 6 axles. The maximum tractive force is therefore approximately 97,000 lb. per locomotive or 16,000 lb. per axle; that is, if there is enough horsepower at the wheel rims to develop the tractive effort.

2.6.3 Drawbar Pull After some of the tractive effort is used to move the locomotive itself, the remaining effort, in the form of drawbar pull, is used to move the rest of the train. As the train speed increases, the tractive effort from the locomotives decreases and the drawbar pull available to move the train also decreases.

Due to the limited strength of drawbars and coupler knuckles, the number of locomotives or motorized axles that can be used in the head end of a train is restricted. Although rated with a minimum strength of 350,000 lb. (general service coupler made of Grade B steel), coupler knuckle failure may happen at 250,000 lb. due to age and wear. Grade E knuckles used on some captive services may have an ultimate strength of 650,000 lb.

To avoid the risk of drawbar failure enroute, it is recommended to limit the number of motorized axles in a locomotive consist to 18 (three 6-axle units). If more tractive

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effort is required to move the tonnage of a train, the option of in-train motive power should be considered.

2.6.4 Train Resistance Train resistance, the force required to move a train, is the sum of the rolling resistance on tangent level track, grade resistance and curve resistance of the locomotives and cars. Other resistances due to wind velocity, tunnels or different train marshalling will not be discussed here.

Rolling Resistance Rolling Resistance is the sum of the forces that must be overcome by the tractive effort of the locomotive to move a railway vehicle on level tangent track in still air at a constant speed. These resistive forces include:

Rolling friction between wheels and rail that depends mainly on the quality of track.

Bearing resistance, which varies with the weight on each axle and, at low speed, the type, design and lubrication of the bearing.

Train dynamic forces that include the effects of friction and impact between the wheel flanges against the gauge side of the rail and those due to sway, concussion, buff and slack-action. The rail-flange forces vary with speed and quality of the wheel tread and rail, as well as the tracking effect of the trucks.

Air resistance that varies directly with the cross-sectional area, length and shape of the vehicle and the square of its speed.

In general, rolling resistance of a train, R (in lb.), can be calculated using an empirical expression as follows:

R = A + B V + C D V2

where A, B, C & D are coefficients defining the different resistive forces that are either independent, dependent or affected by the square of the train speed V.

Davis Formula The first empirical formula to compute rolling resistance was developed by W.L. Davis in 1926. The original Davis formula provided satisfactory results for older equipment with journal bearings within the speed range between 5 and 40 mph. Roller bearings, increased dimensions, heavier loadings, higher train speeds and changes to track structure have made it necessary to modify the coefficients proposed by Davis. Since

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then, there had been various modifications. Interested readers may refer to Section 2.1 of Chapter 16 in the AREMA Manual for Railway Engineering for more information.

Starting Resistance The resistance caused by friction within a railway vehicles wheel bearings can be significantly higher at starting than when the vehicle is moving. Depending on the type of bearings, weight per axle, and the temperature of the bearing, starting resistance can range from 5 to 50 lb/ton. The ambient temperature and the duration of the stop as shown below affect temperature of the bearing.

Type of Bearings

Above Freezing

Below Freezing

Journal Bearing

25 lb/ton

35 lb/ton

Roller Bearing

5 lb/ton

15 lb/ton

Starting resistance is generally not much of a problem with the very large tractive effort available with modern diesel locomotives, except on steeper grades. If necessary, the locomotive engineer can bunch up the train first, then start the train one car at a time. The cars already moving will help start the ones to the rear. This is called taking slack to start.

Grade Resistance Grade Resistance is the force required to overcome gradient and is equal to 20 lb. per ton per percent grade. This force is derived from the resolution of force vectors and is independent of train speed. An up grade produces a resistive force while a down grade produces an accelerating (negative resistive) force. A train moving up a long tangent of 1% grade at 10 mph, a speed that most tonnage trains slow down to at ruling grade locations, will have a train resistance coefficient of 22.4 to 23.5 lb. per ton with the grade resistance accounted for over 85% of the total.

Curve Resistance Curve Resistance is an estimate of the added resistance a locomotive or car must overcome when operating through a horizontal curve. The exact details of the mechanics contributing to curve resistance are not easy to define. It is generally accepted in the railway industry that curve resistance is approximately the same as a 0.04% up grade per degree of curvature (which equals 0.8 lb. per ton per degree of curvature) for standard gauge tracks. At very slow speeds, say 1 or 2 mph, the curve resistance is closer to 1.0 lb. (or 0.05% up grade) per ton per degree of curve.

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C H A P T E R 3 - B A S I C T R A C K

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Basic Track

The engineer will frequently work from a set of standardized railway or transit standards when making his or her selection of track components for any given design project. However, a basic understanding of elementary track componentry, geometry and maintenance operations is necessary if intelligent decisions are to be made within the options that are typically available.

3.1 Track Components e begin our study with the prime component of the track the rail.

3.1.1 Rail Rail is the most expensive material in the track.2 Rail is steel that has been rolled into an inverted "T" shape. The purpose of the rail is to:

Transfer a train's weight to cross ties.

Provide a smooth running surface.

Guide wheel flanges.

2 Canadian National Railway Track Maintainers Course

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Switch Ties

Switch ties (Figure 3-3) are commonly hardwood species, usually provided in either 6" or 12" increments beginning at 9'-0" up to 23'-0" in length. Nominal cross-section dimensions are 7" x 9", although larger ties are specified by some railways. The primary use for switch ties is relegated to turnouts (thus their name). However, they are also used in bridge approaches, crossovers, at hot box detectors and as transition ties. Some railways use switch ties in heavily traveled road crossings and at insulated rail joints. Switch ties ranging in length from 9'-0" to 12'-0" can also be used as "swamp" ties. The extra length provides additional support for the track in swampy or poor-drained areas. Some railways have utilized Azobe switch ties (an extremely dense African wood) for high-speed turnouts. The benefits associated with reduced plate cutting and fastener retention may be offset by the high import costs of this timber.

Softwood Ties

Softwood timber (Figure 3-4) is more rot resistant than hardwoods, but does not offer the resistance of a hardwood tie to tie plate cutting, gauge spreading and spike hole enlargement (spike killing). Softwood ties also are not as effective in transmitting the loads to the ballast section as the hardwood tie. Softwood and hardwood ties must not be mixed on the main track except when changing from one category to another. Softwood ties are typically used in open deck bridges.

Figure 3-3 Switch Timber Photo by Craig Kerner

Figure 3-4 Softwood Timber - Photo by J. E. Riley

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Concrete Ties Concrete ties (Figure 3-5) are rapidly gaining acceptance for heavy haul mainline use, (both track and turnouts), as well as for curvature greater than 2. They can be supplied as crossties (i.e. track ties) or as switch ties. They are made of pre-stressed concrete containing reinforcing steel wires. The concrete crosstie weighs about 600 lbs. vs. the 200 lb. timber track tie. The concrete tie utilizes a specialized pad between the base of the rail and the plate to cushion and absorb the load, as well as to better fasten the rail to the tie. Failure to use this pad will cause the impact load to be transmitted directly to the ballast section, which may cause rail and track surface defects to develop quickly. An insulator is installed between the edge of the rail base and the shoulder of the plate to isolate the tie (electrically). An insulator clip is also placed between the contact point of the elastic fastener used to secure the rail to the tie and the contact point on the base of the rail.

Steel Ties Steel ties (Figure 3-6) are often relegated to specialized plant locations or areas not favorable to the use of either timber or concrete, such as tunnels with limited headway clearance. They have also been utilized in heavy curvature prone to gage widening. However, they have not gained wide acceptance due to problems associated with shunting of signal current flow to ground. Some lighter models have also experienced problems with fatigue cracking.

Figure 3-5 Concrete Ties Photo by Kevin Keefe

Figure 3-6 Steel Ties

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3.1.4 Rail Joints The purposes of the rail joint (made up of two joint bars or more commonly called angle bars) are to hold the two ends of the rail in place and act as a bridge or girder between the rail ends.6 The joint bars prevent lateral or vertical movement of the rail ends and permit the longitudinal movement of the rails for expanding or contracting. The joint is considered to be the weakest part of the track structure and should be eliminated wherever possible. Joint bars are matched to the appropriate rail section. Each rail section has a designated drilling pattern (spacing of holes from the end of the rail as well as dimension above the base) that must be matched by the joint bars. Although many sections utilize the same hole spacing and are even close with regard to web height, it is essential that the right bars are used so that fishing angles and radii are matched. Failure to do so will result in an inadequately supported joint and will promote rail defects such as head and web separations and bolt hole breaks.

There are three basic types of rail joints (Figure 3-8):

Standard

Compromise

Insulated

6 Canadian National Railway, Track Maintainers Course

Figure 3-8 Conventional Bar, Compromise Bar & Insulated Joint Bar Photo by J. E. Riley

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Standard Joints Standard joint bars connect two rails of the same weight and section. (See Figure 3-9) They are typically 24" in length with 4-bolt holes for the smaller rail sections or 36" in length with 6-bolt holes for the larger rail sections. Alternate holes are elliptical in punching to accommodate the oval necked track bolt. Temporary joints in CWR require the use of the 36 bars in order to permit drilling of only the two outside holes and to comply with the FRA Track Safety Standards requirement of maintaining a minimum of two bolts in each end of any joint in CWR.

Compromise Joints Compromise bars connect two rails of different weights or sections together. (See Figure 3-10) They are constructed such that the bars align the running surface and gage sides of different rails sections. There are two kinds of compromise joints:

Directional (Right or Left hand) compromise bars are used where a difference in the width of the head between two sections requires the offsetting of the rail to align the gage side of the rail.

Non-directional (Gage or Field Side) are used where the difference between sections is only in the heights of the head or where the difference in width of rail head is not more than 1/8" at the gage point. Gauge point is the spot on the gauge side of the rail exactly 5/8" below the top of the rail.

To determine a left or right hand compromise joint:

Stand between the rails at the taller rail section.

Face the lower rail section.

Figure 3-9 Standard Head-Free Joint Bar Photo by J. E. Riley

Figure 3-10 Compromise Joint Bar Photo by J. E. Riley

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The joint on your right is a "right hand".

The joint on your left is a "left hand".

Insulated Joints Insulated joints are used in tracks having track circuits. They prevent the electrical current from flowing between the ends of two adjoining rails, thereby creating a track circuit section. Insulated joints use an insulated end post between rail ends to prevent the rail ends from shorting out.

There are three types of insulated joints:

Continuous

Non-continuous

Bonded

Continuous insulated joints (Figure 3-11) are called continuous because they continuously support the rail base. No metal contact exists between the joint bars and the rails. Insulated fiber bushings and washer plates are used to isolate the bolts from the bars. The joint bars are shaped to fit over the base of the rail. This type of insulated joint requires a special tie plate called an "abrasion plates" to properly support the joint.

Non-continuous insulated rail joints are called non-continuous because these joints don't continuously support the rail base. A special insulating tie plate is required on the center tie of a supported, non-continuous insulated joint. Metal washer plates are placed on the outside of the joint bar to prevent the bolts from damaging the bar.

There are two common kinds of non-continuous insulated joints:

Glass fiber.

Polyurethane encapsulated bar.

Figure 3-11 Continuous Insulated Joint Photo by J. E. Riley

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Right-of-Way & Roadway

For this chapter, think of the railway right-of-way as the area from fence to fence without the track and structures. The roadway is considered to be any construction within the right-of-way except the track, bridge structures, signals and crossings.

4.1 Introduction he railway right-of-way (often referred to as the roadway) includes the subgrade upon which the ballast section and track are built, along with adjacent improvements and features required to support and maintain the railway track.

The right-of-way is often thought of as the strip of land on which the railway and its supporting features are built.

The right-of-way typically includes ditches running along the track and related drainage structures required to divert water past and away from the railway. The issue of drainage is covered in Chapter 5. It also includes any embankments and cuts on which, or through which, the railway is built, their side slopes and the vegetation covering the slopes. It may also include any retaining walls or other earth-supporting structures required to hold railway embankment and cut side slopes in place. It includes fences, signs, utilities and outlying structures.

The bulk of this chapter deals with what the railways are built upon, the soil. Just as concrete and steel are the materials used by the structural engineer, soil is the main building material for the railway. In the same way as there are various types of steel, or diverse mixtures of concrete, there are many classifications of soil. Some soils are suitable for use as ballast and sub-ballast (sand and gravel), some as subgrade materials (sand, gravel, clay, etc.), while others are totally undesirable for any use in railway construction (e.g., organic soils).

A major difference between soils and most other construction materials is that soil is a natural material and is subjected to little or no processing before use. It is therefore essential to identify the various soils and avoid using those that may give problems, since it is seldom that soil can be processed to improve its properties. From a

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construction and maintenance over the past 100 years. For instance, it is not unusual for track that functioned very well for more than 50 years to suddenly develop severe geotechnical problems.

In solving problems today, the experiences and effects of the last 100 to 150 years of railway practice must be considered. Not only are the railways dealing with ever-increasing loads and ever-increasing traffic, but also a maintenance effort focused on rails and ties. Ballast, being less visible, receives less attention, and the subgrade, less still except when problems develop. Nonetheless, knowing the history of a section of track is an important component of effective track maintenance.

Components and Functions

Figure 4-4 The Track Structure

The track structure is made up of subgrade, sub-ballast, ballast, ties and rail as illustrated in Figure 4-4. Each of these contributes to the primary function of the track structure, which is to conduct the applied loads from train traffic across the subgrade safely. The magnitudes of typical stresses under a 50,000 lb axle load are shown in Figure 4-5. These stresses are applied repeatedly, and each repetition causes a small amount of deformation in the subgrade. In theory, the track structure should be designed and constructed to limit rail deflections to values which do not produce excessive rail wear or rates of rail failure. In reality, cumulative deformation of the subgrade causes distortion of the subgrade, leading to formation of ballast pockets" (Figure 4-6) or outright shear failure.

SUBBALLAST

SUBGRADE

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Figure 4-5 Stresses Imposed by Train Axle Load

Figure 4-6 Ballast Pockets in Subgrade

Subgrade The purpose of the subgrade is to support the track structure with limiting deflections. Every subgrade will undergo some deflection (strain) as loads (stress) are applied. The total displacement experienced by the subgrade will be transmitted to other components in the track structure. The stiffer the subgrade (i.e., the higher the modulus of elasticity), the lower the deflection values will be. It is important that adequate subgrade strength and stiffness be available on a year-round basis, particularly during spring thaw and following heavy precipitation events.

The strength, stiffness and total deflection of the subgrade can be improved by:

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Carefully selecting materials that are naturally strong (sand, gravel, boulders) with a high angle of internal friction.

Limiting access to water to avoid buildup of porewater pressure and subsequent reduction of strength.

Improving the soil properties, using techniques such as compaction, in situ densification, grouting and preloading.

Maintain good drainage.

Maintain stable subgrade geometry.

Sub-ballast The purpose of sub-ballast is to form a transition zone between the ballast and subgrade to avoid migration of soil into the ballast, and to reduce the stresses applied to the subgrade. In theory, the gradation of the sub-ballast should form a filter zone that prevents migration of fine particles from the subgrade into the ballast. In practice, insufficient attention has been placed to sub-ballast gradation historically, and much of the sub-ballast does not adequately perform that function. This notwithstanding, the number of occurrences of subgrade contamination of ballast are relatively few.

How Track Fails In a nutshell, track fails when differential rail deflections become excessive. This differential deflection may be expressed in differential elevation between tracks, punching of ties, elastic or plastic deformation of the subgrade, or degradation of ballast.

When the bearing capacity of the subgrade is exceeded, the subgrade will deform plastically, resulting in a small amount of permanent deformation under each wheel load. A progressive deterioration of the track begins, as illustrated in Figures 4-7 to 4-10. It starts with minor deflections and may progress to a fully visible surface heave, where subgrade material is pushed above the elevation of the rail and ties. Under those conditions, ballast drainage is impeded, resulting in further softening and degradation of the subgrade to a point where large, saturated pockets of ballast are trapped in the subgrade. Frost heave and further degradation commonly follow, leading eventually to a severe loss of utility of the track structure.

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Figure 4-7 Stable Site

Figure 4-8 Onset of Instability

Figure 4-9 Growth of Heave

Figure 4-10 Surface Manifestation of Heave

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4.3.4 Instability Instability results when the shear strength of the soil is not sufficient to support the loads applied to it. Bearing capacity failures discussed in the previous section are one type of shear failure that occurs when the soil cannot sustain vertical load applied to it and vertically downward movement results. The term landslide is used to define all types of mass movement of soil or rock, where the mass moves down slope under the influence of gravity only. There are many types of landslides, but the distinguishing feature is that a mass of material is moved and gravity is the driving force.

Main Features of Landslides The diagnostic features of most landslides include a scarp that forms at the head of the landslide. This is usually a near vertical wall of soil, usually freshly exposed by movement. The slump blocks are unique, identifiable blocks of soil, usually bounded by scarps that show both vertical and horizontal movement. The main body of the slide is the mass of soil that is pushed ahead by the slump blocks, and may be marked by numerous tension cracks. Bulging of the soil, and thrusting of the slide debris over the natural surface usually mark the toe of the slide. The slip plane or shear zone is usually a distinct and identifiable plane that marks the lower limit of movement and the upper limit of undisturbed soil. It should be noted that the shear zone is not usually planar, but rather may be circular, or a composite curvilinear surface that passes through the weakest zones in the subsurface.

Slides that Affect the Track Instability that affects the track can be classified according to the impact that it has on the track. These are described in various illustrations.

Figure 4-11 illustrates a slide that encompasses a track and will disrupt the track by cutting the alignment. Once the track moves out of line, it is no longer serviceable.

Figure 4-11 Slides Cutting Track

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Figure 4-12 illustrates the effect of a landslide upslope where the toe crosses the track, burying it in under slide debris.

Figure 4-12 Slides Covering Track

Figure 4-13 shows the track being heaved up in response to upward movement of the toe of a landslide.

Figure 4-13 Slides Heaving Track

Figure 4-14 illustrates an event where a landslide threatens the track, perhaps by encroaching on the down slope shoulder.

Figure 4-14 Slides Threatening Track

Figure 4-15 illustrates how base failure in fills on soft foundations can cause the fill to spread and settle. While this may be mistaken as settlement, it is actually a shear movement involving the foundation soils. It is common on organic terrain and other soft foundations.

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Figure 4-15 Base Failure

Figure 4-16 shows how locations over old landslides may be reactivated due to a change in stresses within the landslide mass. Many of the ancient landslides are extremely large, and the limits of the landslides may be difficult to detect.

Figure 4-16 Reactivation of Old Slide

Triggering Mechanisms The stability of a slope is dependent upon:

The shear strength of the soils.

Porewater pressure within the soils that make up the slope (this can be roughly measured by knowing the water table).

The geometry of the slope, particularly the slope angle and changes of slope.

Any surcharge loading such as fill or bank widening material stored on the slope or train loads.

Landslides occur either as a result of reduction in soil strength or an increase in the loading on the slope.

Reductions in soil strength can occur as the result of:

An increase in porewater pressure, reducing the available shear strength of the soil. In the case of moisture sensitive soils, the amount of water needed to cause this

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C H A P T E R 5 - D R A I N A G E

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Drainage

The three most important elements in good track are: #1 Drainage, #2 Drainage and #3 Drainage Darrell Cantrell, Engineer Track (Retired) BNSF

rainage is the subject of stormwater behavior as it relates to the properties of hydrology and hydraulics. This is a subject that is constantly being reviewed on a regular basis within the regulatory bodies of government and it is

therefore always important to review local requirements to guide the engineer through the design process. Even though one method of analysis may be appropriate to use in an area one feels comfortable in, it may not be appropriate in another location. A good rule of thumb is to contact the local highway department as a starting point and continue your investigation to local authorities. The other primary source for the Engineer is the AREMA Manual for Railway Engineering, Chapter 1, Parts 3 & 4.

The engineer needs to be aware that one has to maintain existing drainage patterns and not increase headwaters upstream or downstream. Adjacent property owners, whether they are farmers or city dwellers, have certain rights and are protected under common law concerning storm water conveyance and elevation as it relates to property damage.

5.1 Hydrology For the purposes of this Guide, Hydrology will be defined as the study of rainfall events (inches or inches per hour) and runoff (cubic feet per second) as related to the engineering design of conveyance features such as ditches and culverts. These conveyance features are typically designed to a particular storm event or storm frequency. In other words, a storm water conveyance feature is going to be associated with a certain amount of risk with respect to failure. For instance, a 100 year storm return period has a 1% probability of occurring in any given year, a 50 year storm has a 2% probability of occurring in any given year, and a 10 year storm has a 10% chance of occurring in any given year. So it is up to the designer to assign a certain amount of

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5.3 Recommended Procedures 5.3.1 Existing Drainage Study

Before proceeding with the design of the project, it should be realized that it is always important to visit the actual project site and identify problems that may be encountered. Existing culverts always seem to be a problem and should be looked at carefully. Examples of potential problems include excessive ditch scouring and constant ponding of water along a ditch system. Railway ditches are typically very flat and do not drain well. However, the designer should always review the situation as if there is a solution. If it is economically feasible to remedy the situation, then the area should be regraded and repaired to what is recognized as common engineering practice.

Below is a recommended approach to an existing consistent drainage study:

Utilize a USGS Quadrangle Map or a Hydrologic Atlas (HA) for the area.

Plot existing and proposed railway right-of-way.

Identify floodplain and floodway boundaries.

Identify watershed areas based upon contour interpretation.

Identify existing bridges, culverts and problem areas.

Identify sheet and concentrated flow.

Identify closed drainage systems.

Select outlet points for each watershed area.

Select the proper hydrology criteria (i.e. rainfall, frequency, formula, etc.).

Calculate or run the model and assign flow rates to each of the watersheds.

Add flow rates and hydrographs, as necessary, to determine proper flow through the watershed.

Select the proper hydraulic method to determine storm water elevations.

Conduct a plan-in-hand field review.

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Remember the existing drainage study is the benchmark study on which all proposed drainage features are based.

5.3.2 Proposed Drainage System The proposed drainage system typically addresses impacts to an existing man made or natural drainage system from a proposed improvement. This can take the form of new ditches and culverts or it can take the form of improving existing problem areas. Keep in mind that any improvement to an existing drainage system will more than likely affect surrounding drainage patterns and elevations on adjacent or downstream properties. For example, increasing the size of an existing cross culvert introduces more storm water flow rate to downstream property owners. The designer should determine whether this situation is going to present a problem.

Below is a recommended approach to the design of a proposed drainage system:

Complete and review the existing drainage study.

Superimpose the proposed improvements on a copy of the existing drainage study map.

Locate new drainage features such as ditches, bridges and culverts.

Are there floodplain and wetland impacts?

Never relocate an existing outlet point unless it is absolutely necessary.

Try to maintain existing watershed limits (sometimes these do change).

Calculate the new hydrology for the watershed.

Calculate the new hydraulics for the watershed.

Compare the new data with the existing data at the same points.

Initiate Permitting process.

For adjacent properties, it is ideal to obtain the same results between existing and proposed conditions and it may take a few iterations to obtain those results. Sometimes it is impossible for this to occur. By studying the upstream and downstream effects, the designer may be able to apply a certain amount of change that does not harm or cause damage to adjacent property owners. For example, a 0.1 or a 0.5 increase in headwater may be acceptable, or a 5% increase in flow velocity may be acceptable if the surrounding soil conditions are tolerable. There may be more

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considerations to review. However, this is dependent upon the conditions and regulations unique to that project location.

5.3.3 Floodplain Encroachment Evaluation The floodplain is identified by criteria established by the Federal Emergency Management Agency (FEMA) for the 100-year and 500-year storm events or known depression flood prone areas. Typically, the 100-year base flood elevation is the most commonly regulated stormwater elevation associated with rivers, streams and concentrated flow areas. FEMA, State Water Resource Departments, counties and local communities (that are part of the National Flood Insurance Program) closely monitor flood plain areas. Any change to the flood plain will generally result in extensive studies and computer modeling to be submitted for approval.

Below is a summary of possible floodplain permitting reviews.

FEMA:

Physical Map Change (Extensive Floodplain Revisions)

Letter of Map Revision (Typical Floodplain Revisions)

Conditional Letter of Map Revision (Typical Floodplain Revisions done in the design phase)

Elevation Criteria (Typically for building structures)

US Army Corps of Engineers:

Excavation below normal water elevation

State Water Resource Department:

Floodway (Area within a floodplain that demonstrates conveyance)

County (Some counties may not be involved in the review process):

Floodplain

Floodway

Compensatory Storage (Excavation required to compensate for floodplain filling)

Elevation Criteria (Typically for building structures)

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Railway Track Design

Basic considerations and guidelines to be used in the establishment of railway horizontal and vertical alignments.

he route upon which a train travels and the track is constructed is defined as an alignment. An alignment is defined in two fashions. First, the horizontal alignment defines physically where the route or track goes (mathematically the

XY plane). The second component is a vertical alignment, which defines the elevation, rise and fall (the Z component).

Alignment considerations weigh more heavily on railway design versus highway design for several reasons. First, unlike most other transportation modes, the operator of a train has no control over horizontal movements (i.e. steering). The guidance mechanism for railway vehicles is defined almost exclusively by track location and thus the track alignment. The operator only has direct control over longitudinal aspects of train movement over an alignment defined by the track, such as speed and forward/reverse direction. Secondly, the relative power available for locomotion relative to the mass to be moved is significantly less than for other forms of transportation, such as air or highway vehicles. (See Table 6-1) Finally, the physical dimension of the vehicular unit (the train) is extremely long and thin, sometimes approaching two miles in length. This compares, for example, with a barge tow, which may encompass 2-3 full trains, but may only be 1200 feet in length.

These factors result in much more limited constraints to the designer when considering alignments of small terminal and yard facilities as well as new routes between distant locations.

The designer MUST take into account the type of train traffic (freight, passenger, light rail, length, etc.), volume of traffic (number of vehicles per day, week, year, life cycle) and speed when establishing alignments. The design criteria for a new coal route across the prairie handling 15,000 ton coal trains a mile and a half long ten times per day will be significantly different than the extension of a light rail (trolley) line in downtown San Francisco.

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curves as D (degrees per 20 meter arc). However, there does not seem to be any widespread incorporation of this practice. When working with light rail or in metric units, current practice employs curves defined by radius.

As a vehicle traverses a curve, the vehicle transmits a centrifugal force to the rail at the point of wheel contact. This force is a function of the severity of the curve, speed of the vehicle and the mass (weight) of the vehicle. This force acts at the center of gravity of the rail vehicle. This force is resisted by the track. If the vehicle is traveling fast enough, it may derail due to rail rollover, the car rolling over or simply derailing from the combined transverse force exceeding the limit allowed by rail-flange contact.

This centrifugal force can be counteracted by the application of superelevation (or banking), which effectively raises the outside rail in the curve by rotating the track structure about the inside rail. (See Figure 6-6) The point, at which this elevation of the outer rail relative to the inner rail is such that the weight is again equally distributed on both rails, is considered the equilibrium elevation. Track is rarely superelevated to the equilibrium elevation. The difference between the equilibrium elevation and the actual superelevation is termed underbalance.

Though trains rarely overturn strictly from centrifugal force from speed (they usually derail first). This same logic can be used to derive the overturning speed. Conventional wisdom dictates that the rail vehicle is generally considered stable if the resultant of forces falls within the middle third of the track. This equates to the middle 20 inches for standard gauge track assuming that the wheel load upon the rail head is approximately 60-inches apart. As this resultant force begins to fall outside the two rails, the vehicle will begin to tip and eventually overturn. It should be noted that this overturning speed would vary depending upon where the center of gravity of the vehicle is assumed to be.

There are several factors, which are considered in establishing the elevation for a curve. The limit established by many railways is between five and six-inches for freight operation and most passenger tracks. There is also a limit imposed by the Federal Railroad Administration (FRA) in the amount of underbalance employed, which is generally three inches for freight equipment and most passenger equipment.

Figure 6-6 Effects of Centrifugal Force

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Underbalance limits above three to four inches (to as much as five or six inches upon FRA approval of a waiver request) for specific passenger equipment may be granted after testing is conducted.

Track is rarely elevated to equilibrium elevation because not all trains will be moving at equilibrium speed through the curve. Furthermore, to reduce both the maximum allowable superelevation along with a reduction of underbalance provides a margin for maintenance. Superelevation should be applied in 1/4-inch increments in most situations. In some situations, increments may be reduced to 1/8 inch if it can be determined that construction and maintenance equipment can establish and maintain such a tolerance. Even if it is determined that no superelevation is required for a curve, it is generally accepted practice to superelevate all curves a minimum amount (1/2 to 3/4 of an inch). Each railway will have its own standards for superelevation and underbalance, which should be used unless directed otherwise.

The transition from level track on tangents to curves can be accomplished in two ways. For low speed tracks with minimum superelevation, which is commonly found in yards and industry tracks, the superelevation is run-out before and after the curve, or through the beginning of the curve if space prevents the latter. A commonly used value for this run-out is 31-feet per half inch of superelevation.

On main tracks, it is preferred to establish the transition from tangent level track and curved superelevated track by the use of a spiral or easement curve. A spiral is a curve whose degree of curve varies exponentially from infinity (tangent) to the degree of the body curve. The spiral completes two functions, including the gradual introduction of superelevation as well as guiding the railway vehicle from tangent track to curved track. Without it, there would be very high lateral dynamic load acting on the first portion of the curve and the first portion of tangent past the curve due to the sudden introduction and removal of centrifugal forces associated with the body curve.

There are several different types of mathematical spirals available for use, including the clothoid, the cubic parabola and the lemniscate. Of more common use on railways are the Searles, the Talbot and the AREMA 10-Chord spirals, which are empirical approximations of true spirals. Though all have been applied to railway applications to

Figure 6-7 Overbalance, Equilibrium and Underbalanced

UNDERBALANCE

Superelevation

CentrifugalForce

Gravity

Resultant

Center ofGravity

EQUILIBRIUM

Superelevation

CentrifugalForce

Gravity Resultant

Center ofGravity

OVERBALANCE

Superelevation

GravityResultant

CentrifugalForceCenter of

Gravity

DEV a0007.0

3max

+=

= Maximum allowable operating speed (mph).= Average elevation of the outside rail (inches).= Degree of curvature (degrees).D

EV

a

max

Amount of Underbalance

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6.4 Alignment Design In a perfect world, all railway alignments would be tangent and flat, thus providing for the most economical operations and the least amount of maintenance. Though this is never the set of circumstances from which the designer will work, it is that ideal that he/she must be cognizant to optimize any design.

From the macro perspective, there has been for over 150 years, the classic railway location problem where a route between two points must be constructed. One option is to construct a shorter route with steep grades. The second option is to build a longer route with greater curvature along gentle sloping topography. The challenge is for the designer to choose the better route based upon overall construction, operational and maintenance criteria. Such an example is shown below.

Figure 6-9 Heavy Curvature on the Santa Fe - Railway Technical Manual Courtesy of BNSF

Suffice it to say that in todays environment, the designer must also add to the decision model environmental concerns, politics, land use issues, economics, long-term traffic levels and other economic criteria far beyond what has traditionally been considered. These added considerations are well beyond what is normally the designers task of alignment design, but they all affect it. The designer will have to work with these issues occasionally, dependent upon the size and scope of the project.

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On a more discrete level, the designer must take the basic components of alignments, tangents, grades, horizontal and vertical curves, spirals and superelevation and construct an alignment, which is cost effective to construct, easy to maintain, efficient and safe to operate. There have been a number of guidelines, which have been developed over the past 175 years, which take the foregoing into account. The application of these guidelines will suffice for approximately 75% of most design situations. For the remaining situations, the designer must take into account how the track is going to be used (train type, speed, frequency, length, etc.) and drawing upon experience and judgment, must make an educated decision. The decision must be in concurrence with that of the eventual owner or operator of the track as to how to produce the alignment with the release of at least one of the restraining guidelines.

Though AREMA has some general guidance for alignment design, each railway usually has its own design guidelines, which complement and expand the AREMA recommendations. Sometimes, a less restrictive guideline from another entity can be employed to solve the design problem. Other times, a specific project constraint can be changed to allow for the exception. Other times, its more complicated, and the designer must understand how a train is going to perform to be able to make an educated decision. The following are brief discussions of some of the concepts which must be considered when evaluating how the most common guidelines were established.

A freight train is most commonly comprised of power and cars. The power may be one or several locomotives located at the front of a train. The cars are then located in a line behind the power. Occasionally, additional power is placed at the rear, or even in the center of the train and may be operated remotely from the head-end. The train can be effectively visualized for this discussion as a chain lying on a table. We will assume for the sake of simplicity that the power is all at one end of the chain.

Trains, and in this example the chain, will always have longitudinal forces acting along their length as the train speeds up or down, as well as reacting to changes in grade and curvature. It is not unusual for a train to be in compression over part of its length

Figure 6-10 Automatic Coupler

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(negative longitudinal force) and in tension (positive) on another portion. These forces are often termed buff (negative) and draft (positive) forces. Trains are most often connected together with couplers (Figure 6-10). The mechanical connections of most couplers in North America have several inches (up to six or eight in some cases) of play between pulling and pushing. This is termed slack.

If one considers that a long train of 100 cars may be 6000' long, and that each car might account for six inches of slack, it becomes mathematically possible for a locomotive and the front end of a train to move fifty feet before the rear end moves at all. As a result, the dynamic portion of the buff and draft forces can become quite large if the operation of the train, or more importantly to the designer, the geometry of the alignment contribute significantly to the longitudinal forces.

As the train moves or accelerates, the chain is pulled from one end. The force at any point in the chain (Figure 6-11) is simply the force being applied to the front end of the chain minus the frictional resistance of the chain sliding on the table from the head end to the point under consideration. As the chain is pulled in a straight line, the remainder of the chain follows an identical path. However, as the chain is pulled around a corner, the middle portion of the chain wants to deviate from the initial path of the front-end. On a train, there are three things preventing this from occurring. First, the centrifugal force, as the rail car moves about the curve, tends to push the car away from the inside of the curve. When this fails, the wheel treads are both canted inward to encourage the vehicle to maintain the course of the track. The last resort is the action of the wheel flange striking the rail and guiding the wheel back on course. Attempting to push the chain causes a different situation. A gentle nudge on a short chain will generally allow for some movement along a line. However, as more force is applied and the chain becomes longer, the chain wants to buckle in much the same way an overloaded, un-braced column would buckle (See Figure 6-12). The same theories that Euler applied to column buckling theory can be conceptually applied to a train under heavy buff forces. Again, the only resistance to the buckling force becomes the wheel/rail interface.

Figure 6-11 Force Applied Throughout the Train - ATSF Railroad Technical Manual - Courtesy of BNSF

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Communications and Signals

Types, Theory of Operation and Design Considerations of Train Control and Railway Communications and Signals Systems.

his chapter contains a basic description of the types and theory of operation of Communications and Signals Systems, their application and design considerations. Due to the safety sensitive nature of these systems, the

examples and/or sample formulas in

01 - practical guide torrailway engineering.pdf

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