Denver Regional Transportation District (RTD)

System-wide Traction Power Study

The Denver light rail transit system began service in 1994 with a 5.3- mile starter line.  With the success of this starter line, the system rapidly expanded with the Southwest Line to Littleton that opened in July of 2000.

Continuing success of this system has allowed Denver Regional Transportation District (RTD) to continue with two additional line segments:

  • A 1.6 mile extension west and north of downtown to Denver Union Terminal which opened in 2002
  • A new 19-mile Southeast Corridor LRT Line (the “T-Rex Project”) which opened on November 17, 2006 and includes a 15-mile main line through the Denver Tech Center and a 4-mile branch parallel to the I-225 beltway.

For each of these extension projects, LTK served as the systems engineering consultant responsible for signals, communications, traction electrification (substations and overhead contact system), corrosion control design, fare collection systems engineering, procurement management and start-up testing and acceptance.

LTK’s traction power work included system-wide simulation studies performed using our proprietary software tools. The studies included the existing system, new systems, and extensions. Effect of various operating headways and various consist sizes were evaluated on the existing traction power system.  The traction power simulations assisted LTK engineers in determining the substation ratings and spacing, as well as confirmed the suitability of selected OCS conductors.

During construction, LTK supported RTD with review of the contractor’s final design, installation support, start-up testing and change order and progress payment review.

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Massachusetts Bay Transportation Authority (MBTA)

Blue Line Traction Power Simulation

The Blue Line provides heavy rail rapid transit service between downtown Boston and communities located to the northeast of Massachusetts’ largest city. As part of the Blue Line No.5 car procurement, a traction power study was performed to determine the impacts the new car would have on the existing traction power system.  The power study modeled the new No. 5 car in a 6-car consist operating under peak (rush-hour) conditions.  The Blue Line traction power system was modeled with composite (aluminum and steel) third rail in the tunnel from Bowdoin to Airport station.  At Airport station the traction power supply transitions to an overhead contact system (OCS) for the remainder of the line to Wonderland station. 

The main concern addressed by the study was to resolve whether the new car operating under maximum train length and peak period headways would cause any rail voltage degradation that would negatively affect trip times.  At the same time, the loadings of the Blue Line traction power substations were evaluated versus the nameplate ratings of each unit to confirm that no overloading was occurring in the simulation.

The No. 5 car is a modern electronically-controlled vehicle equipped with AC inverter drive propulsion system.  The No. 5 cars are operating in the interim “phase in” period with the existing, cam-controlled, No. 4 cars until the complete Blue Line fleet is completely replaced.

The MBTA has ordered 94 new No. 5 cars (47 pairs) with stainless steel bodies from Siemens Transportation Systems. The first of the new cars began service on February 20, 2008. The entire No. 5 fleet is expected to be in service by the end of 2009.

The scenarios used to perform the study included assessment of the traction power system with various vehicle configurations, including the propulsion system with current limiting and/or reduced acceleration.  The study also considered the impact of new substations, increased nominal voltage at the existing substations and the installation of additional conductors to the distribution system and substation feeders.

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Northeast Illinois Regional Commuter Railroad Corp. (Metra)

Metra Electric District Traction Power Study

LTK performed a comprehensive analysis of the Electric District traction power system operated by Metra, the commuter rail division of the Regional Transportation Authority (RTA).  Taking into account the recent and projected passenger volume increases, the study evaluated augmentation and upgrade of the existing system and compared it to system conversion to either 2x12.5 kV or 25 kV traction power system.  The study included the following:

  • TP03-MetraEvaluation of the existing 1,500 Vdc traction power supply and distribution system and whether it should be converted to a new electrification system operating either at 2x12.5 kV ac or 25 kV AC electrification voltage.
  • Necessary modifications to the existing traction power system to supply year 2020 traction loads.
  • Definition of new equipment requirements and the equipment ratings.
  • Development of realistic, least service-disrupting and most cost-effective approach for implementing the system augmentation.
  • Evaluation of additional renovation and upgrades.
  • Cost estimates of the system augmentation and upgrade.

For conversion to 2x12.5 kV or the 25 kV traction power system, the following analyses were performed:

  • Development of the new system configuration using traction power system simulations.
  • Voltage increase and use of commercial frequency impact on vehicle modifications, overhead catenary system clearances and signaling system compatibility.
  • Environmental impact of the system conversion.
  • Operational impacts of voltage and frequency changes on Metra and the Northern Indiana Commuter Transportation District (NICTD).
  • Schedule development for cost-effective approach for implementing the system conversion.
  • Impacts of construction of new transmission lines for power supply to new substations.

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Metro-North Railroad

Replacement of Signal System Power Motor-Alternator Sets

Metro-North Railroad (MNR) serves a vital transportation function to ensure the mobility of commuters in the New York metropolitan region. The on-time performance, service reliability and safety of the Railroad’s daily operations depend heavily on the reliability of the signal system. To ensure the continued reliability of this critical system, MNR has decided to review the current condition and future replacement needs of the motor-alternator sets and the associated equipment. 

TP04The MNR system operates rotary machines for conversion of power utility three-phase, 13.8 kV, 60 Hz power to single-phase, 480 V, 100 Hz power. The machines consist of a synchronous motor and synchronous alternator mounted on a common shaft. The 480 volt output of the alternators is stepped up to 2,400 volts for Hudson and Harlem lines and 12,000 volts for New Haven line for transmission to the signal houses via network of cables and overhead lines. 

As part of a General Engineering Services contract, LTK evaluated the need for replacement or refurbishment of the existing equipment.  LTK performed a comprehensive industry survey to determine the feasibility of using static converters in lieu of rotary machines for power conversion. 

LTK designed the replacement of MNR’s aging signal power generation system at six substations located in New York State.  This included replacement of the 13.8 kV switchgear, step-up and step-down transformers, power cables, and control wiring.  The older motor-alternators will be replaced with new equipment; the more recent vintage ones will be refurbished.

During the design, several improvements to the system were implemented to provide MNR with better reliability and operational flexibility.  Modern, microprocessor control equipment, protective equipment and instrumentation were specified.  A new SCADA system interface was provided, and Human-Machine Interface (MNI) and Intelligent Electronic Devices (IEDs) were specified.

Old air break switches were specified to be replaced with modern circuit breakers and vacuum interrupters. Existing conduits, cable spaces and concrete pads will be reused in order to cause minimal impact on the existing structures while the equipment upgrade is being made. 

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National Railroad Passenger Corporation (Amtrak)

25 Hz vs. 60 Hz Study

Northeast Corridor (NY to DC)

LTK performed a comprehensive analysis and computer load-flow simulations of the following traction power system configurations suitable for re-electrification of the Northeast Corridor between Washington, DC and New York, NY, Harrisburg Line, and various commuter branch lines:

  • TP05System 1: Upgrade of the existing 12 kV/25 Hz multiple-fed system with new or renovated electrical equipment.
  • System 2: Conversion of the existing system to a new 12 kV multiple-fed system operating at 25 Hz.
  • System 3: Conversion of the existing system to a new 12 kV multiple-fed autotransformer system operating at 25 Hz.
  • System 4: Conversion of the existing system to a new 25 kV center-fed system operating at 60 Hz.
  • System 5: Conversion of the existing system to a new 25 kV autotransformer center-fed system operating at 60 Hz.

Based on the power study, design of each system was carried to a conceptual engineering level and included identification of substation locations and development of rating of major items of equipment such as transformers and static frequency converters. A comprehensive cost estimate was developed for each of the five systems that included both capital and O&M costs. A life cycle analysis for the two most cost-effective alternatives was performed and its sensitivity to inflation and interest rates evaluated.

Electrical power utility restructuring was reviewed and its impact on Amtrak was evaluated. The possibility of Amtrak’s entrance into the transmission marketplace was also assessed. Amtrak’s power transmission capability was evaluated and its augmentation was studied considering increase in conductor sizes, conversion to three-phase operation, increase in transmission voltage, building of additional circuits and transmission lines. Cost estimates for various transmission voltage levels, corridor lengths and power transmission capability were developed. Amtrak’s potential for financial gain and loss was assessed and the value of Amtrak’s right-of-way in terms of transmission capabilities was estimated.

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New York Power Authority (NYPA)

Traction Power System Study and Energy System Storage Analysis

on New York City Transit System

LTK performed a study to identify, evaluate, and quantify potential benefits of aluminum contact rail and energy storage systems, such as batteries, supercapacitors, and flywheels, including energy consumption and power demand savings and improvement in system voltage profile. 

TP06-NYPAIn order to accomplish this, traction power modeling and train operation simulations were performed on a set of typical system configurations.  The simulations were performed using specially developed software capable of representing train operation along an alignment and predicting the effects of regeneration and generic energy storage systems on maximum power demand requirements, energy consumption, and voltage improvement.

The study confirmed that power demand and energy savings are possible by implementing the aluminum contact rail, the energy storage system, or both.  Further, both technologies improve the voltage profile along the alignment.

In order to determine whether any one or more energy storage systems and the aluminum contact rail are economically viable, comprehensive financial analyses evaluating costs and benefits of the various options were performed.  The project costs included initial capital investment costs and annually recurring costs, such as the operation and maintenance (O & M) costs.  The project benefits included power demand and energy savings, as well as improvement in voltage profile along the system.  LTK computed the benefits of the projects using three different financial models – the Payback Period Method, the Return on Investment Method and the Net Present Value of Life-Cycle Costs/Benefits Method.

Traction power simulations of the Queens Boulevard and Lexington Avenue lines were performed and application of energy storage devices evaluated.  Both lines are four-track, high throughput lines where considerable energy savings can be achieved by regeneration.  Adding the energy storage devices resulted in marginal additional savings.

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Tri-County Metropolitan Transportation District of Oregon (TriMet)

Banfield, Westside Hillsboro, and I-Max Corridors


Among LTK’s family of clients, no agency better demonstrates LTK’s systems engineering skill than TriMet. Over the past quarter century, and several major projects, LTK has helped TriMet create a light rail system that has earned international acclaim. The firm has participated in the Banfield Corridor Light Rail Project, Banfield Double-Tracking Project, Westside Corridor Light Rail Extension, Hillsboro Light Rail Extension, Airport Light Rail Extension, Interstate Light Rail Extension, I-205 PE and Final Design, Mall Final Design and Washington County Commuter Rail. Throughout this development period, LTK has served and continues to serve as TriMet’s consultant for systems engineering. This nearly unprecedented level of continuous client service stands as a clear testimony to the quality of LTK’s work.

TP07-TriMetLTK served as TriMet’s Systems Engineering Consultant for the initial Banfield Corridor Light Rail Project (The Eastside Line).  LTK engineers functioned as an extension of TriMet’s staff with responsibility for conceptual design, preliminary engineering, final design and construction/procurement management for all systems elements, which included 16 traction power substations, overhead contact system (OCS), system-wide ductbank, train control/signal system, train-to-wayside communications (TWC), radio communications system, and corrosion control design. LTK also was responsible for all systems inspection, testing, integrated testing and start-up.

Final engineering for the light rail project began in mid-1980, and construction began in early 1982.  The overhead contact system is catenary construction in open track areas and trolley wire in more visually-sensitive downtown areas. Now known as the Eastside leg of the Blue Line of MAX (Metropolitan Area Express), revenue service began in September 1986, and gained immediate public acceptance. Initial daily ridership of 20,000 grew steadily to nearly 40,000 per day in 2005. The system is internationally acclaimed for its moderate cost (built under budget), aesthetic urban design and cost-effective operation.

For the Banfield, Westside Hillsboro, and I-Max Corridors, LTK’s software tools were used to simulate the performance of the TriMet traction power system prior to commencing final design.  With more than 40 route-miles (nearly all of which is double track), the system has substations operating at 750 VDC and 825 VDC. The traction power simulation studies determined the substation ratings and spacing, confirmed the suitability of selected OCS conductors, and yielded substation energy consumptions for operating cost estimates.

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Sound Transit

Central Rail Transit Project

LTK assumed the role of systems engineering consultant in 1998 for Sound Transit’s Link program. Leading a team of 32 specialty engineering, architectural and professional services firms, including 22 with offices in the Central Puget Sound region and 20 of which are certified M/W/DBE organizations, LTK was involved in conceptual design and preliminary engineering to support a EIS/FFGA process for the Central Line, a 25-mile corridor from the University of Washington in north Seattle through downtown and the SeaTac airport to a major park and ride facility at South 200th Street.

TP08-SoundTransitAs part of this initial assignment, the LTK team completed conceptual design, preliminary engineering and final design of the Tacoma Line, a 1.6-mile stretch in downtown Tacoma from the multi-modal Tacoma Dome Station to the Theatre District. The systems engineering elements for both Link programs include light rail vehicles, communications and central control systems, train control signals, traction power with overhead contact system, stray current protection and corrosion control analysis and design, system-wide electrical design, and operations maintenance planning support. LTK has total responsibility for maintenance facilities, including all civil, architectural, track, electrical, mechanical and industrial issues.

LTK’s proprietary software tools were used to support the design of the traction electrification system for the proposed Central Link alignment.  The simulation analysis confirmed that the system is capable of supporting variable length train consists, varying headways, and system contingency outages.  Two-, three-, and four-car consists were studied operating at two-, four-, and eight-minute headways in various sections of the route.  The simulation analysis also confirmed the rating and spacing of traction power substations as well as the adequacy of the planned OCS conductor sizes.

The LTK contract was extended in January 2000 to include final design of the systems elements and program management for the vehicle procurement for the Central Line and construction management services for the Tacoma Line and the LTK‑designed maintenance facility was completed. The Tacoma Link, just 30 miles south of Seattle, was put into operation in August 2003. LTK administered the vehicle contract and managed the construction coming in under budget and on-time. The Link’s ridership has exceeded all projections.

The shop and yard substations have been delivered, installed and tested. Three streetcars were ordered and were shipped from the Czech Republic in July 2002, arriving in early September in Tacoma. By late 2002, track and a portion of the overhead contact system had been installed, and the streetcars were under test.

Due to budgetary concerns, the Central Line project was shortened to a 14-mile project. LTK has continued with its final design activities, including completion of design work on the maintenance facility and yard, within the common core of the new alignment. LTK also has assisted Sound Transit in preparation of a Request for Proposals for 31 low-floor light rail vehicles, which was issued in early 2003. This resulted in a procurement contract which was awarded to Kinki Sharyo in January 2004. LTK was also involved in design support during construction and construction management activities for all system elements.

The initial operating segment opened for revenue service on July 18, 2009, followed by an extension to Seattle-Tacoma International Airport. Daily ridership is estimated to be 26,600 by 2010. LTK was responsible for the design of approximately $300 million in systems contracts out of the total $2.1 billion Central Link budget. LTK also supported the new EIS process for finding an affordable and acceptable route north to Northgate, a program referred to as North Link.

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Southeastern Pennsylvania Transportation Authority (SEPTA)

Commuter Rail Traction Power Substations

TP09-SEPTALTK performed final design of two traction power substations to serve SEPTA’s 25 Hz Regional Rail (commuter rail) network.  The work included preparation of procurement documents, specifications and drawings for 12 kV switchgear, 24 kV switchgear, 46 kV circuit breakers, autotransformers, and associated equipment.  Design studies included a short circuit study, ground grid design, protective relay study, transient recovery voltage study, arc-flash evaluation, and insulation coordination study.

LTK assisted SEPTA with construction related services.  The scope of work included coordination with contractor and suppliers, design reviews, approval of components and equipment, and test witnessing.

This work follows a comprehensive traction power load-flow study of the rail network formerly owned by the Reading Railroad (12 kV/24 kV, 25 Hz system) and the Pennsylvania Railroad (12 kV, 25 Hz system).  The study recommended installation of new static frequency converter substations in both the former Reading and former Pennsylvania Railroad sections of the commuter rail system.

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National Railroad Passenger Corp. (Amtrak) 

Feasibility of Self-generation and Cogeneration for Amtrak's Traction Power System

In its search for long-term, cost-effective, and reliable source of energy for its Northeast Corridor operations, Amtrak requested LTK to investigate the feasibility of application of self-generation or cogeneration.  Self-generation is an efficient energy conversion process which generates electrical energy from fossil fuel.  Cogeneration is even more efficient energy conversion process as it generates electrical and thermal energies from fossil fuel.

TP10-AmtrakIn the study, the energy generation processes were reviewed and compared, including the utility and non-utility generation.  The non-utility generation included, self-generation, cogeneration and tri-generation.  Typical system arrangements were defined covering the various types of prime movers, generators, heat recovery systems, thermal energy distribution systems and utility/traction power system interface.

Based on the traction power system power demand studies performed for the “South End” (Washington – New York – Sunnyside, Queens) and “North End” (New Haven – Boston) Amtrak systems, a conceptual design of self-generation and cogeneration plants was developed for application to each substation.  Included were South End frequency converter substations in Jericho Park, Lamokin, Richmond, Metuchen, Sunnyside and North End substations in Branford, New London, Warwick and Sharon.

Feasibility of the self-generation and cogeneration technologies was evaluated by conducting a comprehensive cost/benefit analysis.  The procedures selected for evaluation included payback period method, return on investment method, present value (discounted cash flow) method, and internal rate of return method.  The analysis revealed that although self-generation was not economically feasible for Amtrak, cogeneration showed much more promise if Amtrak could make use of the thermal energy or find customers who would purchase the thermal energy under contracts.

Additionally, the study reviewed federal regulations including the Public Utility Regulatory Policies Act (PURPA), the Energy Policy Act (EPACT), and applicable Federal Energy Regulatory Commission (FERC) orders.  On the state level within the Northeast Corridor, the activities of the Public Service Commissions and the Departments of Environmental Protection were summarized.  Finally, LTK identified the various permits required to implement a cogeneration plant as well as potential institutional/regulatory barriers to cogeneration.

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Southeastern Pennsylvania Transportation Authority (SEPTA)

Rail Network Modernization Program

As a part of SEPTA's rail network modernization program, LTK performed comprehensive studies and design services for the 12 kV/25 Hz Regional Rail Division traction power system.  The studies included:

  • TP11-SEPTASystem modeling, determination of system impedances and development of one-line diagram
  • Computer simulation of the train operation, the traction power system load flows and voltage profile along the system
  • System grounding study
  • Short circuit study
  • Protective relay setting study

These studies provided a platform for the preliminary engineering and detailed design work which included:

  • Study of the present transportation operation
  • Site identification
  • Site drawings for each new substation
  • Autotransformer and switchgear sizing
  • Substation ground mat designs
  • Detailed procurement specification for 12 kV and 24 kV, 25 Hz vacuum type, draw-out switchgear
  • Design of the Traction Power Distribution Center building, including preparation of electrical, mechanical and civil/structural/architectural design documents
  • Development of cost estimates and economic feasibility assessment

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Metropolitan Transit Authority of Harris County

Light Rail System

Houston’s new light rail system encompasses a 7.5-mile corridor extending from the University of Houston-Downtown to the Astrodome and Astroworld. Primarily located in dedicated lanes of existing streets, the system interfaces with approximately 80 intersections, including more than 50 equipped with traffic signals.

TP12-HoustonLTK was awarded a preliminary engineering contract in late 1999 as part of an overall general engineering project for all systems elements for the line. The firm had responsibility for planning and design for the vehicles, traction electrification (substations and overhead contact system), signals, communications and central control, fare collection and corrosion control.  As part of preliminary engineering, LTK developed solicitation documents for each system element as part of an overall design/build contract for this project.

As a member of the Program Management team, LTK had responsibility for reviewing the design and manufacturing of the state-of-the-art light rail vehicles for Houston’s new light rail system. The firm also has responsibility for management of Systems Contractor’s work for the traction power, overhead contact system, signal, communications and control center elements. LTK also worked closely with METRO on development of the Operating and Start-up Plan for the new system. LTK staff has supervised the quality control/quality assurance during construction of the LRVs and also supervised installation of all systems elements in Houston.

All of the project design, manufacture, construction, and testing were performed in record time and the system opened for revenue operation in just four years.

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Peninsula Corridor Joint Power Board (Caltrain)

Traction Power System Modeling and Simulation

TP13-CaltrainLTK performed comprehensive modeling and simulations of the traction power supply and distribution systems proposed for the Caltrain system electrification from San Francisco to Gilroy.  The studies were performed for various traction power configurations and included both locomotive-hauled and Electric Multiple Unit (EMU) trains.  The studies confirmed that both traction electrification systems under consideration -- the 1x25 kV center-fed system with five substations and the 2x25 kV autotransformer-fed system with three substations -- are acceptable and can support the forecast traffic density.

LTK also performed a conductor thermal analysis which revealed that the proposed overhead contact system conductors are satisfactory.  The transient and steady–state temperatures remained well below the conductor temperature limits recommended by the manufacturers.

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