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From page 22... ... 22 C H A P T E R 3 3.1 Introduction This chapter provides a detailed description of capacity analysis methods and tools to assess the ability of a rail line segment to carry a given volume and mix of railroad traffic, while meeting the service quality goals of the operator or operators. Capacity is a function of: • Physical characteristics of the line segment, such as single or double track, distance between passing sidings, signal system characteristics, permitted speeds for different train types, curvature and gradients. Read the entire page →
From page 23... ... Analytical Approaches to Line Capacity in Shared-Use Corridors 23 3.2 Complexity of Shared Railroad Operations Section 1.3 of Chapter 1 provided a short introduction to railroad operations, describing some of the major features and defining common terminology. This section amplifies that discussion by introducing some other key factors that must be considered in capacity analysis. Read the entire page →
From page 24... ... 24 Capacity Modeling Guidebook for Shared-Use Passenger and Freight Rail Operations line segment, causing delays that can propagate quickly through a large railroad system. This is why it is often necessary to perform capacity analysis well beyond the territory proposed for passenger service. Read the entire page →
From page 25... ... Analytical Approaches to Line Capacity in Shared-Use Corridors 25 and locomotives can fail for a variety of reasons. Operations must be managed taking into account regular inspection and maintenance requirements, and an expectation of typical unplanned delays. Read the entire page →
From page 26... ... 26 Capacity Modeling Guidebook for Shared-Use Passenger and Freight Rail Operations but are likely to be costly. Operations changes to increase capacity are likely to be less costly and can be implemented more quickly, but may be limited to smaller incremental improvements. Read the entire page →
From page 27... ... Analytical Approaches to Line Capacity in Shared-Use Corridors 27 all-new right-of-way. This section also describes common modeling building blocks that are not complete models in themselves, but are often elements in a capacity model. Read the entire page →
From page 28... ... 28 Capacity Modeling Guidebook for Shared-Use Passenger and Freight Rail Operations 3.4.2.3 Grid Time Analysis Another relatively simple scoping method is known as a grid time analysis, which is used to test the upper limit for the number of daily trains a corridor can handle, without consideration of individual train service commitments. The theoretical capacity to handle traffic on single track is dictated by the time it takes a train to travel the distance between two sidings and clear the way for an opposing train. Read the entire page →
From page 29... ... Analytical Approaches to Line Capacity in Shared-Use Corridors 29 In the upper illustration, an eastbound train is progressing past one siding to another. The time it takes to run from being stopped at point A to point C is 30 minutes. Read the entire page →
From page 30... ... 30 Capacity Modeling Guidebook for Shared-Use Passenger and Freight Rail Operations requirements) ;, track outages for repairs and maintenance; spacing between block signals and interlockings; and queuing at entrances of terminals and junctions. Read the entire page →
From page 31... ... Analytical Approaches to Line Capacity in Shared-Use Corridors 31 3.4.3 Operations Simulation Analysis Methods Simulation analysis has become the principal method by which line capacity issues are resolved, both in North America and overseas. These models provide a step-by-step simulation of all trains operating on a specific line segment to create a complete and accurate picture of operations. Read the entire page →
From page 32... ... 32 Capacity Modeling Guidebook for Shared-Use Passenger and Freight Rail Operations 3.4.4 Modeling Objectives and Model Data Requirements A key issue in capacity analysis, which affects how the models are used and the usefulness of results, is the level of detail in infrastructure and operations data needed by the models. All capacity models need these data at some level of detail to achieve their objectives. Read the entire page →
From page 33... ... Analytical Approaches to Line Capacity in Shared-Use Corridors 33 3.5.1.1 Input Data and Model Operation While different models may vary in level of detail and emphasis given to different aspects of a rail operation, the primary data input categories will be as follows: • Details of the trains operating over the line segment, including weight, locomotive power and braking characteristics. The level of detail can vary between a generic freight or passenger train and the make-up of each individual train. Read the entire page →
From page 34... ... 34 Capacity Modeling Guidebook for Shared-Use Passenger and Freight Rail Operations Normally the initial and final periods of the simulation are discarded as unrepresentative. These warm-up and cool-down periods can range from a few hours to a day each. Read the entire page →
From page 35... ... Analytical Approaches to Line Capacity in Shared-Use Corridors 35 It is also necessary to consider planned or likely changes in passenger and freight traffic over a term of up to 20 years. This is because track access agreements between freight railroad and a passenger rail operator should have a long life to avoid frequent renegotiations. Read the entire page →
From page 36... ... 36 Capacity Modeling Guidebook for Shared-Use Passenger and Freight Rail Operations 3.5.2 Descriptions of Individual Capacity Models This section describes various capacity analysis tools that rely on the simulation of rail operations over a selected rail corridor. 3.5.2.1 NCFRP Web-based Freight-Passenger Rail Corridor Project Screening Tool The National Cooperative Freight Research Program's (NCFRP) Read the entire page →
From page 37... ... Analytical Approaches to Line Capacity in Shared-Use Corridors 37 delay for trains involved. RTC is commonly used to develop operating plans, diagnose bottlenecks, recommend schedule changes, evaluate various improvements to the rail infrastructure, and assess the impact of adding new trains to the corridor. Read the entire page →
From page 38... ... 38 Capacity Modeling Guidebook for Shared-Use Passenger and Freight Rail Operations rail industry, it is used by commuter and passenger agencies due to its ability to simulate train movements within controlled terminal areas. The RAILSIM package includes simulation and design capabilities for many types of train control systems, including fixed block and moving block systems. Read the entire page →
From page 39... ... Analytical Approaches to Line Capacity in Shared-Use Corridors 39 between nodes to be directly input and used as the fundamental operational criteria for current and proposed operations. Their value is that a relatively quick, high level analysis can be performed but a more detailed, data intensive approach will still be required in advance of any specific project designs. Read the entire page →

From page 22...

... 22 C H A P T E R 3 3.1 Introduction This chapter provides a detailed description of capacity analysis methods and tools to assess the ability of a rail line segment to carry a given volume and mix of railroad traffic, while meeting the service quality goals of the operator or operators. Capacity is a function of: • Physical characteristics of the line segment, such as single or double track, distance between passing sidings, signal system characteristics, permitted speeds for different train types, curvature and gradients.