1 As societal attitudes toward fossil fuels shifts, commuter railroads may be coming under 2 increased scrutiny for their contribution to greenhouse gas (GHG) emissions. This analysis 3 explores new possibilities created by battery -electric locomotiv es (BELs) in conjunction with 4 partial electrification for en -route recharging in electrified territory. We propose a systemwide 5 network approach that starts with one or more substations in geographically strategic locations, 6 then electrifying just enough for sufficient electrical charge , with BELs running off the wire in 7 non-electrified areas. As 25,000 -Volt alternating -current substations generally have an 18~26- 8 mile reach , considerable possibilities exist for new -start electrifications. This is signifi cantly 9 more cost -effective than a traditional approach that electrifies one corridor at a time. Although 10 BELs are in technical development, and certain implementation challenge s remains on commuter 11 railroads , we believe BELs required to enable this type o f electrification are within reach of 12 current battery technology. 13 Drawing on examples in Boston, Philadelphia, Chicago, and Minneapolis, six strategies 14 are outlined: (1) minimizing electrification costs by electrifying radial commuter network s from 15 a centrally -located substation, (2) for systems with longer routes, using BELs to extend the 16 central substation ’s reach , (3) extending new electric service beyond existing electrifications 17 with BELs, (4) using BELs to create new trans -regional services, (5) co-locating railroad -owned 18 feeder lines with utility infrastructure such as electric transmission rights -of-way to maximize the 19 geographic reach of supply substations , and (6) providing charging pads in certain limited 20 situations . Preliminary ridership, ene rgy sufficiency , and lifecycle cost analyses were performed 21 to show the feasibility of BEL technology in conjunction with a substation -based , supply -side 22 approach to designing electrification projects . 23 24 Keywords: Commuter rail , electrification , supply substations , battery -electric locomotive s, 25 charge -in-motion . 26 27 28 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 3 INTRODUCTION 1 As societal attitudes move away from fossil fuels in favor of carbon -neutral renewable energy, 2 commuter rail operators are respond ing to these concerns. In 2021 , Metra, northeastern I llinois’ 3 commuter railroad, issued a request for proposals for battery -powered locomotives ( 1). The 4 California Department of Transportation has ordered four Stadler hydroge n-powered multiple - 5 units for use on the San Joaquin route ( 2). Although halted in 2022, New York’s Long Island 6 Rail Road and Alstom were actively developing a retrofit battery package for existing electric 7 multiple -unit (EMU) cars ( 3). 8 Electrification, already undergoing a mild renaissance in the early 21st century, merit s a 9 closer l ook, and not just for environmental reasons. Advances in battery technology are leading 10 to a paradigm shift without precedent in the history of railroad electrification that should greatly 11 reduce the capital cost of new installations. 12 Modern battery -electric locomotives (BELs) with an energy capacity of 7.2 megawatt - 13 hours (MWh ) were announced in 2021 (4). The authors have previously demonstrated (5) that a 14 four-unit consist of these BELs are capable of hauling freight trains of up to 8,000 tons for 230 15 mainline miles unassisted, potentially enabling discontinuous electrification of major freight 16 lines. When combined with en -route charging on high -voltage alternating -current (AC) 17 catenary, BELs potentially offer a revolutionary technology for commuter rail roads looking to 18 reduce d iesel train -miles for greenhouse -gas (GHG) emission and climate -related reasons. 19 Conceptually, BELs resemble existing dual -mode AC electric /diesel locomotives, already 20 operating on one major commuter railroad (Figure 1) , except that their off -wire power comes 21 from batteries , which are charged up while under the wire. 22 23 24 Figure 1. NJ Transit dual -mode locomotive entering Convent Station, 2021. Fan Railer photo (CC BY -SA 4.0). Source: https://commons.wikimedia.org/wiki/File:ALP -45DP_Convent_Station.j pg 25 26 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 4 Although early 20th-century electrifications used lower voltages, the geographic reach of 1 25,000 -Volt (25kV) AC electrification at 60 -Hertz (Hz) commercial frequency create s new 2 possibilities in combination with rapidly -developing BEL technology. Although BELs can work 3 with already -existing electrifications involving lower voltages, the greater reach of 25kV enables 4 longer electrifications to be powered from one single substation, which in turn can reduce 5 infrastructure costs or extend the reach of electric service. BELs themselves further extend the 6 range of electric service by running off -wire beyond electrified trackage. 7 No BELs have been specifically built for commuter service as of this writing. But given 8 the state-of-art in battery technolog y—driven by the automotive field (6)—and successes of 9 current freight -oriented prototype BEL s, vendors should be able to develop BELs suitable for 10 commuter service should an appropriate specification be issued . Several conceptual designs 11 already exist , e.g., (7). This paper describes how this technology, when fully proven, could be 12 used. 13 Our approach to electrification planning is to electrify busier inner -suburban segments, 14 supplemented with BELs or ba ttery EMUs for outer, quieter segments, offering a cost-effective 15 path forward. Preliminary analyses conducted for this effort show that once produced, BELs 16 should have the range needed to extend electric service to exurban areas and beyond. 17 This concept combines traditional electric operations with BEL s, and have been 18 previously discussed at a conceptual level ( 8, 9 pp. 168). It had been previously explored with a 19 hydrogen fuel -cell stack in conjunction with a hybrid powertrain ( 10), prior to high -capacity 20 batteries becoming available. Previous work o n a concept termed “intermittent electrification” 21 with very short live-wire segments and gaps ( 11) applied to reducing GHG emissions from 22 passenger rail with dual -mode diesel locomotives ( 12) was found to be unworkable because 23 feeder wire and substation -related issues were overlooked (13). A recent optimization study 24 examined the location of electrified track necessary to advance such a concept (14). Indeed, 25 Deutsche Bahn may be close to implementing such a concept in Schleswig -Holstein ( 15) with 26 minimum electrified segments of several hundred metres at 15kV AC, 16.7 Hz . 27 This study is distinct from previous work in several significant ways . Our approach 28 keeps the electrified segments contiguous to the maximum extent possible, based on the 29 maximum reach o f 25kV supply substations, recognizing that substations are a major part of 30 electrification expense. We utilize BELs in place of diesel dual -mode units to operate through 31 unelectrified territory, thereby achieving 100% GHG elimination at the point of use, rather than a 32 partial solution. Finally, and perhaps most importantly, we sketch out what practical designs on 33 U.S. systems might look like , using case studies on existing and proposed U.S. commuter and 34 regional rail systems, thereby advancing this idea beyond the conceptual stage. 35 36 Context of Climate Change 37 Human activities are estimated to have caused between 0.8°C to 1.2°C (1.4°F to 2.2°F) of global 38 warmi ng above pre -industrial levels, which is likely to reach 1.5°C before 2052 ( 16). Thus, t he 39 United Nations Intergovernmental Panel on Climate Change (IPCC) has called for a 40% 40 reduction of GHG emissions by 2030 to avoid climate consequences associated with average 41 warming of greater than 1.5°C . Some industry groups describe zero -carbon rail as a “nece ssity” 42 by 2050 ( 17). 43 Diesel locomotives emit GHGs and contribute to climate change. As automobile and bus 44 fleets are hybridized or electrified, today’s environmental arguments in favor of diesel -powered 45 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 5 commuter rail will become harder to sustain. To re duce diesel train -miles, operators must either 1 cut service or replace diesels with non -GHG -emitting propulsion technologies. 2 3 Research Objectives 4 This paper offers a high -level, first -cut feasibility analysis for BEL -enabled commuter rail 5 electrification. It aims to: (a) identify existing commuter rail services that could be electrified for 6 climate change action; (b) show how single -substation configurations in combination with BELs 7 could make electrification less costly than conventional designs; and (c) show that two 4.8 -MWh 8 BELs have the range to perform all but the most demanding duties in typical commuter and 9 inter-regional services, if enough of the core network is electrified. 10 11 Limitations of This Research 12 Our research does not address such implement ation issues as upgrading electrical grids for 13 climate -neutral power generation, or infrastructure -based site -specific restrictions (equipment 14 weight, length, special requirements, etc.). Nor does it evaluate mode shift alternatives (e.g., 15 from diesel tra ins to electric buses), offer ridership forecasts, or address the longstanding debate 16 between locomotives and EMUs (18). It also does not determine whether railroads are more 17 GHG -efficient with electrification than with alternate fuels such as hydrogen, nor does it 18 investigate environmental concerns about the fabrication and dispos al of batteries or the 19 consequences of mining the necessary semi -precious metals . However, it is worth noting that 20 liquefied natural gas (LNG), “genset” locomotives, and operati ng diesel locomotives in “hybrid” 21 configurations are not carbon -neutral options ( 5). 22 Nor is t his paper a “business case” for commuter rail electrification. North American 23 commuter and intercity passenger rail services require operating support, and such support is not 24 generally driven by energy costs. From a return -on-investment perspective, the balance of 25 electric power versus diesel largely depends on assumptions about relative energy costs. 26 Perhaps most importantly, this research does not consider track ownership, jurisdictional 27 issues, or other institutional matters. It is assumed that solutions can be found, as in 28 Massachusetts (19), New York, Virginia, Florida, California, and Ontario. 29 For general background on railroad electrification , readers are referred to the extant 30 literature (20-25), including research on design alternatives ( 26), electric traction power supply 31 (27, 28), and alternatives to diesel traction ( 9 pp. 135 -177). 32 33 HISTORICAL REVIEW OF NORTH AMERICAN ELECTRIFICATION S 34 In the early 20th century, railroads that could afford the substantial expense electrified some or , 35 occasionally, all of their suburban services to solve specific operating issue s where steam was 36 unworkable or inadequate (29, 30). The reasons why they electrified included long tunnels, 37 underground stations, sustained grades, increas ing train throughput through faster handling , 38 general economy of operation (particularly in conjunction with intercity passenger and freight 39 trains), and elimination of fossil -fuel locomoti ve smoke for civic improvement purposes (31). 40 Interestingly, these reasons for electrifying remain valid . 41 The post-World War II emergence of diesel -electric locomotive s (9, 32) transformed 42 North American railroads and reduced the operating advantages o f electric traction. Mechanical 43 engineers and manufacturers quickly settled on diesel -electrics as the motive power of choice. 44 Diesel -electrics, being essentially electric locomotives with self -contained diesel generators, 45 combined the geographic flexibi lity of steam with the high torque of electric locomotives (33). 46 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 6 Push -pull operation with diesel locomotives and cab cars started on the Chicago & North 1 Western in 1960 (34) and quickly spread to other commuter railroads . This made diesel 2 locomotives as easy to use in commuter service as EMUs. 3 Re-electrifications and other renewals of already -electrified commuter rail lines offered 4 the first tentative signs of reinvestment in electric traction infrastructure . Several re - 5 electrifications switched over fr om direct current (DC) or low -frequency AC to commercial - 6 frequency, 60 -Hz AC (35): 7 8  New Jersey Transit, Morris & Essex Lines, from 3,000V DC to 25kV AC, 60 Hz, 1984 9  Metro -North Railroad, New Haven Line, from 11kV AC, 25 Hz to 12.5kV AC, 60 Hz, 10 1986 11  Agence Métropolitaine de Transport (Montréal, Québec), Deux -Montagnes Line, from 12 2,400V DC to 25kV AC, 60 Hz, 1995 13 14 First -Wave Electrification Renaissance 15 Adding to the extent of existing electrification s was a logical follow -on to renewals of older 16 installations . Three New York area commuter railroads added significant extensions to existing 17 electrifications (1982 -2002) . Several new -start installations, all at 25 kV AC, followed : 18 19  Amtrak Shore Line Route, Boston, Massachusetts to New Haven, Connecticut, 2000 20  Ferrocarril Suburban o de la Zona Metropolitana del Valle de México, Mexico City, 2008 21  Regional Transportation District, Denver, Colorado, 2016 22 23 Two other properties are in the process of electrifying at this writing: 24 25  Caltrain, San Francisco to San Jose, Cal ifornia 26  GO Transit , multiple lines , Toronto, Ontario , Canada 27 28 Figure 2 shows the Caltrain electrification, which uses hardware typical of modern 29 electrifications. 30 Two unsuccessful proposals and a third yet in play were also part of this first wave: 31 32  In 2012, an otherwise -promising plan to electrify three commuter rail lines in Montréal, 33 Québec, Canada failed when the freight railways, which own the tracks, announced their 34 opposition to electrification. 35  In Chicago, Metra, northeastern Illinois’ commuter railroad, considered electrifying some 36 or all of the Rock Island District (which Metra owns and operates) in 2018. The 37 interesting aspect was not that Metra found the costs exceeding the benefits, but that this 38 proposal failed to advance by only a small m argin. 39  Finally, in Boston, as of late 2022 the Massachusetts Bay Transportation Authority 40 (MBTA) appeared to be ready to proceed with electrifying the Fairmount Line, which 41 serves an urban corridor and provides an alternative to the Northeast Corridor ma inline 42 between Boston and Readville, Massachusetts ( 36). 43 44 This early 21st century renaissance occurred against a backdrop of rising commuter rail ridership 45 between 1983 and the start of the COVID -19 pandemic in 2020 ( 37). At first glance, the 46 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 7 pandemic’s effects on ridership might imply an end or at least a pause to the present wave of 1 electrification. Recent controversies about electrification costs ( 38) and the applicability of 2 battery -electric traction to rail passenger service (39) based on questiona ble assumptions have 3 further confused matters. But a second wave of interest in electrification may be imminent as 4 ridership recovers, led by increasing unease about GHG emissions and their impact on climate 5 change. 6 7 8 Figure 2. Section of completed Caltrain electrification work at Cali fornia Avenue, Palo Alto, California, 2022. Dick Lyon photo (CC BY -SA 4.0). Source: https://commons.wikimedia.org/File:Caltrain_electric_infrastructure_in_Palo_Alto.jpg 9 10 Current Approaches to Dual -Mode Motive Power 11 Amtrak is currently procuring Siemen s Charger locomotives mated to Auxiliary Power Vehicles 12 (APV s), which draw power from overhead catenary and could optionally be fitted with batteries 13 (40). Metro -North’s dual -mode procurement (41) may include an option for battery tenders that 14 would suppl y power to adjacent locomotives. 15 Responding to these market demands, Siemens is reportedly designing a version of the 16 Charger locomotive (designated M42 -DMC) with lithium -ion batteries that could operate in 17 battery and diesel modes, recharging from railroad power sources where available . When this 18 locomotive is built , it could provide the capability for a demonstration passenger service that 19 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 8 would span existing electrified and non -electrified territories. Although t hese approaches 1 involve diesel locomoti ves which might, as an option, be provided with energy storage capacity 2 rather than BEL s, this represent s a significant first step toward reducing the proportion of diesel 3 train-miles relative to total service . 4 5 Further Electrification Renaissance? 6 Until r ecently, new standards (Tier s 2, 3, and 4) restricting particulate and noxious emissions 7 from new and rebuilt diesel locomotives (42, 9 pp. 123 -133) had seemingly raised the threshold 8 for justifying electrification . Now, though , concern about GHG emission s may have the opposite 9 effect of making electrification more desirable. 10 Current alternative fuels and propulsion technologies have their limitations. Hydrogen 11 lacks the concentrated energy density of fossil fuel, and even under the best of circumstanc es is 12 likely to underperform relative to diesel or biodiesel ( 20 pp. 10 -11). Thus, GO Transit 13 considered but rejected hydrogen power as being inadequate for its busy and growing system 14 (43, 44). In 2022, Metrolink converted from fossil -fuel diesel to a r enewable diesel fuel (RD99) 15 refined entirely from modern carbon (i.e., carbon other than that contained in fossil fuels) . To 16 the extent that RD99 production removes CO 2 from the atmosphere, overall net reductions of 17 65~90% of carbon emissions might be pos sible ( 45), but it does not entirely eliminate GHG 18 emissions. Today’s concern with reducing the carbon footprint of transportation increases the 19 likelihood that the environmental benefits of commuter rail electrification (powered from 20 carbon -neutral sourc es) will be fully appreciated. 21 The second -wave electrification renaissance is likely to take two forms. One is 22 conventional electrification using overhead catenary system s (OCS) , as in Denver, San 23 Francisco, and Toronto . The second involves the emerging technology of battery -electric 24 locomotives (BELs). 25 26 STRATEGIES FOR COMMUTER RAIL ELECTRIFICATION 27 We propose some strategies and ideas to minimize both capital and operating costs of electri fied 28 commuter rail service in the context of reducing GHG emission s, using examples from Boston, 29 Philadelphia, and Chicago . Table 1 summarizes the strategies discussed herein . Because partial 30 electrification requires approaches that differ great ly from those hitherto used for conventional, 31 continuous electrification, t hese paradigm -shifting strategies are examined first . 32 33 34 Table 1. Summary of partial electrification strategies . 35 36 Strategy Description Case Study Opportunities for Use 1 Take Advantage of Commuter Rail’s Star Network Topology Boston Northside New -start commuter rail electrification where the network has a central terminal and multiple branches extend ing up to 25 miles from a central yard or station 2 Use Battery -Electric Locomotives to Extend Reach of Central Electric Substation Boston Northside Network s with a central terminal where multiple branches extend 25~50 miles out, especially if exurban areas seek new or continued service 3 Extend Service Beyond Existing Electrification with BELs Philadelphia Reading -side Existing electrified networks where ex urban services were previously discontinued, but localities now seek service restoration or extension Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 9 Strategy Description Case Study Opportunities for Use 4 Create Trans -Regional Services Spanning Electrified Zones Using BELs Mid-Atlantic Regional Network Connecting two or more electrified commuter rail networks where a “gap” in electrical infrastructure exists in the areas between them 5 Take Advantage of Co - Located Infrastructure Chicagoland North and West New -start commuter rail electrification where the network extends more than 50 miles from the downt own, or where ridership density on one or more lines is so high that a straight -electric service is warranted on them, and adjacent branches or extensions are in relatively close proximity 6 Charging Pads Regional Services Terminating in Smaller Locales Isolated, very long lines where a single charge from downtown cannot reliably carry the train through to the final destination, and/or shore power may be needed at the outlying yard to maintain charge during weekend layovers 1 2 Following descriptions of these strategies is a more technical discussion of the methods used . 3 Evaluating these different strategies and determining the feasible operating ranges of BELs 4 require s data analysis and technical computations using standard industry formulas. Table 2 5 summ arizes the methodologies used and major findings. 6 7 8 Table 2. Summary of methodologies used for evaluating case studies 9 10 Methodology Description Opportunities for Use Major Findings A Analysis of Cumulative Passenger Loads by Line versus Mileage from Down town To determine what fraction of passenger would cross the zone boundary between straight - electric and BEL zones 24% of Boston Northside exurban passengers are in the BEL zone. 14% of Chicagoland North and West riders would require BEL or shuttle servic e. B Energy Assessment for Service Feasibility and Market Scan of Electrification Using Battery Electric Locomotives To determine if given extension service could operate with BELs using existing electrification, or how much electrification is needed to support a new -start BEL line Most commuter lines can be operated with BELs if slightly less than half the route -mileage is electrified. Very few services require charging pads at the outer ends, and only under very specific circumstances and assumptions. C Life Cycle Cost Analyses of Financial Feasibility of BEL - Enabled Electrification To compare the cost and performance of BEL -enabled electrification versus more traditional electrification network designs BEL -enabled electrification represents a 25%~44% l ifecycle cost savings over conventional solutions, depending on extent to which service is extended into or curtailed from the surrounding exurbs and countryside. D Simplified Battery Charge Level Simulation of an Established Operating Plan To assess the risk of battery depletion on an individual train basis and determine logistical plans in case of battery depletion and assess shore power requirements AM peak inbound service has the lowest battery levels due to overnight HEP load, but fleet manipulations to get locomotives with low battery warnings onto daytime charge cycles are not difficult even on lines with relatively sparse service frequency. E Infrastructure Efficiency and GHG Reduction Comparative Assessment To compare cost and effectiveness of dif ferent approaches towards GHG reduction BEL -enabled approaches achieve 100% GHG reduction with 20% to 64% of route -miles electrified, depend ing on rolling stock utilization goals. Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 10 1 2 Key to these strategies is a supply -oriented approach to electrification . In a classical 3 service -centric approach, sponsors decided what services should be electrified, and given that 4 scope, railroad engineering departments determined what infrastructure was needed to 5 implement the project. Instead, we stand this logic on it s head. Starting with a strategically 6 located substation, we ask how much of the network can be electrified? This might affect such 7 operating matters as storage yards, crew bases, etc., but given the significant range of 25kV 8 electrification from supply substations, designers should have considerable flexibility to identify 9 solutions. 10 For this analysis, we assumed that on shared freight/passenger corridors, catenary 11 electrification can co -exist with double -stack container trains, or freight trains can be re-routed if 12 necessary. As it should be possible to operate electric locomotives at speeds up to 100 mph with 13 overhead wires dimensioned for double -stack container trains ( 46 pp. 2 -3), such clearances 14 would not be problematic for commuter rail operations . 15 Where electrified lines with lower wires have flat junctions with other railroads, short 16 gaps may be needed in the catenary wire s to accommodate freight trains , particularly if double - 17 stack container trains use the intersecting line . (This situatio n already exists on the Northeast 18 Corridor in southwestern Connecticut, where there is a short gap in the wires when crossing the 19 Cob movable b ridge over the Mianus River .) We have previously provided ( 5) a list of next 20 steps necessary to prove out that cat enary electrification can co -exist with double -stack freight 21 trains in North America. 22 We now turn to the strategies themselves. 23 24 Strategy 1: Take Advantage of Commuter Rail’s Star Network Topology 25 Classic commuter rail network s radiate from a downtown location in all directions, typically with 26 a shared train servicing facility nearby. Modern 25kV AC, utility -frequency, autotransformer - 27 fed system s have a maximum range of 18 ~26 miles from supply substations (up to 52 miles 28 between substations) , depending on such factors as design and power draw . Commuter rail 29 power requirements are on the lower end of theoretical catenary capacity , thereby maximizing 30 substation range. This range allows the network’s highest -density segments to be covered from 31 one single, centrally located supply station . This is especially true if a trunk line runs several 32 miles from downtown before splitting into branches, or if the servicing facility is located a few 33 miles out. 34 Figure 3 shows the hypothetical extent of electrification from one supply substation ( with 35 3 to 5 autotransformer paralleling substations on each branch) for Boston’s Northside commuter 36 rail system. All core suburban markets , which encompass line segments serving 83.6% of total 37 ridership —see Figure 4, and Metho dology A , below —can be covered from a single substation at 38 the Boston Engine Terminal (B.E.T.) , shown in Figure 5 . Any operatio ns beyond the electrified 39 zone would require connecting service s. Some parts are at the far end of the 25kV transmission 40 range and may experience low -voltage conditions under certain circumstances. 41 Admittedly, a single -supply configuration has reliability consequences. However, those 42 effects can be mitigated by multiple utility feeds at the central locati on, and BELs or , as an 43 interim step, electro -diesel dual-mode locomotives for some services. Additional feeder 44 locations might eventually come online for reliability enhancement and as electrified services 45 expand beyond the suburban core. But as a starter electrification syst em, this is a highly cost - 46 effective configuration. 47 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 11 1 2 NORTH STATIONMANCHESTER MP 25.4ROCKPORT (MP 35.3) HAMILTON/WENHAM MP 22.7NEWBURYPORT (MP 36.2) LAWRENCE MP 26.0HAVERHILL (MP 32.9) LOWELL MP 25.5 SOUTH ACTON MP 25.3 B.E.T. (MP 0.8)TERMINAL STATION LIMITS OF 25kV ELECTRIFICATION ASSUMED LOCATION OF SUPPLY SUBSTATIONLegend Boston Northside Commuter Rail Network Approximate Maximum Extent of 25kV Electrification with Downtown Supply Substation StrategyCOMMUTER RAILWAY UNELECTRIFIED SEGMENTWACHUSETT (MP 53.7) Figure 3. Boston Northside Commuter Rail network case study: central supply substation strategy (Strategy 1), showing m aximum feasible electrification at 25kV with one single supply substation at the Boston Engine Terminal . 3 4 (A) Boston % of ridership by line and by mile (B) Boston ridership count by line and by mile 0%10%20%30%40%50%60%70%80%90%100% 0 10 20 30 40 50 60Percentage of Customers Miles from BostonMileage versus Percentage of Customers Framingham/Worcester Greenbush Kingston/Plymouth Middleborough/Lakeville Providence/Stoughton Providence Stoughton Franklin Needham Fairmount Fitchburg Lowell Haverhill Newburyport/Rockport Newburyport Rockport 05,00010,00015,00020,00025,00030,00035,00040,00045,00050,000 0 10 20 30 40 50 60Number of Customers Miles from BostonMileage versus Number of Customers Framingham/Worcester Greenbush Kingston/Plymouth Middleborough/Lakeville Providence/Stoughton Providence Stoughton Franklin Needham Fairmount Fitchburg Lowell Haverhill Newburyport/Rockport Newburyport Rockport Figure 4. Commuter Rail ridership statistics for Boston showing v isualization by line, station, and mileage , emphasizing lines selected for partial electrification case study . Source: Massachusetts Bay Transportation Authority (47). 5 6 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 12 Figure 5. Boston Engine Terminal, also known as the Commuter Rail Maintenance Facility, a possible site for a 160 MW supply substation. Nick Allen photo (CC BY -SA 4.0). Source: https://commons.wikimedia.org/wiki/ File:MBTA_Commuter_Rail_Maintenance_Facility_aerial.jpg 1 2 Strategy 2: U se BELs to Extend the Reach of Basic Electrification 3 There might be markets beyond the 18~26 -mile radius that are important for ridership, 4 operational, or jurisdictional reasons. High -capacity BELs can serve these markets seamlessly, 5 even without 25kV wires reaching important suburban terminals like Haverhill and Fitchburg . 6 Figure 6 show s the approximate maximum BEL ranges beyond the hypothetical core 7 25kV network, based on the charging time available between entering the electrified zone 8 inbound and leaving it on the next outbound run —see Methodology B, below . We only need to 9 build the minimum electrification necessary to keep BELs sufficiently charged to reach outlying 10 terminals and return to the electrified zone. Therefore, less electrification is needed than in 11 Figure 3, particularly where we know service on a specific branch is unlikely to extend beyond 12 the current terminal ( as with Rockport, at the end of a peninsula). 13 14 15 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 13 NORTH STATIONBEVERLY MP 18.3ROCKPORT (MP 35.3)NEWBURYPORT (MP 36.2) ANDOVER MP 22.8EXETER, NH (MP 50.4) LOWELL MP 25.5 SOUTH ACTON MP 25.3WACHUSETT (MP 53.7) B.E.T. (MP 0.8)Boston Northside Commuter Rail Network Approximate Maximum Extent of Electric Service with Downtown Supply Substation/Battery -Electric LocomotivesTERMINAL STATION LIMITS OF 25kV ELECTRIFICATION ASSUMED LOCATION OF SUPPLY SUBSTATION ELECTRIC COMMUTER RAILWAY BATTERY LOCOMOTIVE EFFECTIVE RANGELegend MANCHESTER, NH (MP 55.5) SALEMREADINGHAVERHILL FITCHBURG Figure 6. Boston Northside Commuter Rail network case study: central supply substation strategy with battery - electric locomotives (Strategy 2), showing minimum necessary electrification at 25kV with one single supply substation at the Boston Engine Terminal . 1 2 Another advantage of this setup is that branching may occur near the maximum range of 3 a single 25kV substation (e.g., Newburyport and Rockport). These b ranches necessarily increase 4 electrification costs because infrastructure is less cost -effective on lower -density 5 segments. BELs respond to this challenge by serving lower -density areas without having to 6 install and maintain expensive catenary infrastruct ure. 7 Some outer terminals, where many communities have sought commuter rail since 1981, 8 extend well beyond the extent of current diesel service. Although funding and governance 9 matters remain yet to be solved, BELs combined with a central supply substat ion could extend 10 service well beyond boundaries formerly thought possible or desirable. (Because outlying 11 jurisdictions benefit from BEL service extensions, commuter rail agencies may well expect these 12 outer areas to help pay for the core electrification .) 13 This approach also allows more frequent EMU or electric locomotive service on the 14 highest -density segments, assuming sufficient track and yard capacities. Our operating plan 15 assumptions (Table 3) include 100% electric services to Reading, Lowell, South Acton, and 16 Beverly Depot, supported by new yard tracks at Lowell and near Salem. However, the 9.6 MWh 17 sets of two BELs are effectively drop -in replacements for the current F -40 or GP -40MC 18 locomotives. There is no specific need to replace the existing co aching stock unless additional 19 service is sought . Further study will be needed to definitively establish operating plan 20 alternatives that feasible infrastructure expansion can accommodate . 21 22 23 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 14 1 Table 3. Operating and service plan details for Boston Northsi de case study (Strategy 2) . 2 3 Line Service Plan Fitchburg BEL expresses to Wachusett, electric local trains to South Acton. Trains to be crewed from Fitchburg, South Acton, and B.E.T. BEL trains to be stored at Wachusett. Electric South Acton service to be thinned out in the late evening and sets combined with late night outbound EMUs to Lowell for storage. Sets to be deadheaded back to Boston for early AM EMUs to/from Acton. Lowell BEL expresses to Manchester NH, electric local trains to Lowell. Trai ns to be crewed from Manchester, Lowell, and B.E.T. Trains to be stored at Manchester and a new yard at Lowell. Haverhill BEL expresses to Exeter, NH to run via Wildcat Branch, electric locals to Andover via Reading. Electric trains will be stored at Re ading in an expanded Reading Middle facility. BEL trains continue to be stored at Bradford. Trains to be crewed from Bradford, Reading, and B.E.T. Regional trains to operate with limited stops within the commuter zone. Newburyport/ Rockport BEL express es to Newburyport/Rockport, electric local service to Beverly Depot. Trains to be crewed from Newburyport, Rockport, Beverly Depot, and B.E.T. Trains to be stored at Newburyport, Rockport, and a new yard built within the Salem -Peabody Link right -of-way. 4 5 With Strategy 2, most core suburban markets (line segments serving 76% of total 6 ridership —see Table 4, and Methodology A , below) —can be covered from a single substation at 7 the Boston Engine Terminal (B.E.T.). Figure 7 is a zero -origin cumulative rider ship chart, 8 visually confirming based on its ballistic -projectile parabolic shape that most ridership density 9 lies within the inner suburban zone which can receive straight -electric service. 10 11 12 Table 4. Electrification performance metrics for Boston Norths ide case study (Strategy 2). 13 14 Line Weekday Ridership Ridership Receiving Electric Service % Electric % BEL % Shuttle Line Length (Miles) Miles Electrified % Electrified Fitchburg 17,480 12,210 70% 30% 0% 53.7 25.3 47% Lowell** 21,046 21,046 100% 0% 0% 55.5 25.5 46% Haverhill** 14,026 9,940 71% 29% 0% 50.4 22.8 45% Newburyport 16,679 10,963 66% 34% 0% 36.2 18.3 51% Rockport 12,367 8,129 66% 34% 0% 35.3 18.3 52% Boston North 81,598 62,288 76% 24% 0% 231.1 110.2 48% 15 Note: ** The Boston North ridership statistics given here assume Alternative V (Figure 9) with no additional 16 passengers on the New Hampshire extensions. In all likelihood, the ridership counts on the Lowell and Haverhill 17 Lines would be higher by 2,000~3,000 daily trips each due to the incr eased patronage from the extensions. 18 19 20 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 15 02,5005,0007,50010,00012,50015,00017,50020,00022,50025,000 0 10 20 30 40 50 60Weekday Ridership Miles from Downtown T erminalMiles from Downtown vs Ridership Receiving Electrified Service (Boston*) Fitchburg Lowell Haverhill Newburyport RockportElectrified ZoneBEL Zone* includes estimated ridership to N.H. Figure 7. Distance -ridership relationship for Boston Northside case study (Strategy 2). 1 2 Figure 8 shows an artist’s conception of what commuter BELs operating in charging 3 mode might look like; a BEL -hauled trai n is passing an electric multiple -unit near the supply 4 substation at B.E.T. The cabless booster behind the locomotive provides necessary additional 5 energy storage. 6 7 8 9 10 Figure 8. Battery -electrics on the Boston Northside lines; artist’s concept by J ohn G. Allen. 11 12 13 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 16 1 Life Cycle Cost Analyses 2 We performed a hypothetical lifecycle cost analysis of Strategies 1 and 2 (Methodology C, 3 below) , compared with a more conventional strategy of electrifying the entire network with 4 straight electric locomotives, to diff erent extents. Based on our assumptions, t he results show 5 that the BEL -enabled single -substation design (Strategy 2) saves 25%~44% in total ownership 6 costs, with the range dependent on how far commuter services extend beyond the electrified 7 zone. BELs ca n extend the range of a single central -city substation from 18~26 miles to about 8 50 miles from downtown, sufficient for all but the most dispersed regions. Figure 9 summarizes 9 our findings. 10 11 12 $0.0 $0.5 $1.0 $1.5 $2.0 $2.5 $3.0 $3.5 (I) (II) (III) (IV) (V)Life Cycle Cost ($ billions)Electrification Lifecycle Cost Assessment (Boston) Maintenance of Equipment (NPV) Maintenance of Way (NPV) Infrastructure Capital Fleet CapitalAlternatives: (I) BEL + Single S.S., All Existing (II) Single S.S. only, Partial Service (III) All Electric, All Existing (IV) with Extensions (V) BEL w/ Extensions25%44% Figure 9. Summary of lifecycle cost analysis findings for B oston Northside case study. Note: NPV=Net Present Value; S.S.=Supply Substation. 13 14 15 Adapting Battery -Electric Locomotives 16 Battery prototypes existing in 2022 (4) ride on two three -axle radial trucks, weigh 215 tons (36 17 tons per axle), and store 2.4 MWh of energy. Specification details for next -generation 7.2 MWh 18 BELs are unclear at this writing (48), although being designed primarily for freight service, they 19 might be quite heavy. This configuration is not optimal for commuter service, due to weight 20 limit ations on some commuter trackage, and because three -axle trucks may not ride well at 21 commuter train speeds. 22 Commuter operations with BELs normally require locomotives to be charged while 23 operating under catenary. Although most commuter runs do not requir e 7.2 MWh of energy, it is 24 typically necessary to charge at rates of around 2.4 MW to pick up sufficient charge while power 25 is available. As grid -scale batteries typically have a C/4 charging rate (49), enough cells need to 26 be carried to provide charging bandwidth. Future battery technologies might improve on these 27 capabilities (50). 28 With current technology, w e expect a 4.8 MWh BEL could be carried on two two -axle 29 trucks using a n F-40-type chassis. For our simulations, we have assumed this configuration , 30 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 17 with the necessary charging bandwidth being provided by two 4.8 MWh BELs with 1.2 MW of 1 charging capacity each. Where they are situated in the consist does not affect the calculations. 2 We assumed this hypothetical 4.8-MWh BEL weighs 148 tons, the maxim um weight 3 generally allowable on two two -axle trucks, although further design work may result in higher 4 energy capacities or lighter axle loads . These assumptions are intended to show what should be 5 possible assuming current or near -future technology . 6 Various ideas have been proposed for realizing such a hypothetical 4.8 MWh BEL. One 7 idea that went to the conceptual design stage ( 51) involves reclaiming retired F -40 locomotives 8 and retrofitting batteries within the space formerly occupied by the prime mo ver. In fact, this 9 appears to be the approach taken by the current Metra procurement ( 1). Another idea involved 10 reclaiming retired AEM -7 locomotives and attaching an adjacent tender for batteries. Validating 11 these proposals, which will require prototypi ng, lies outside of the scope of this research. 12 13 Strategy 3: Extend Service Beyond Existing Electrification s With BELs 14 The b enefits of BELs are not limited to new -start electrifications. They can also serve areas 15 heretofore without commuter rail service d ue to low ridership density, and expand into new 16 territory without extending electrification . 17 Diesel service on Philadelphia ’s commuter rail system ended in 1981 for several reasons, 18 including lack of funding, the need for electric propulsion through the Center City tunnel ( which 19 opened in 1984 , replacing the above -ground Reading Terminal ), and a lack of diesel 20 maintenance facilities due to the institutional disaggr egation of commuter and freight service s 21 (52, 53, 54 p. 63 ). However, communities formerly served have long expressed a desire for a 22 return of rail service. 23 24 Markets Reached 25 We performed conceptual calculations ( described in Methodology B, below ) to determine the 26 maximum range for BELs beyond existing electrifi cations , based on reasonable assump tions 27 about consist size . The key markets of Pottstown and Quakertown , Pennsylvania , and Bound 28 Brook , N.J., for connections to New York , could be served by BELs running round -trip service s 29 between these key destinations and Philadelphia 30th Street (Figure 10). However, the extended 30 markets of Reading, Allentown, and Newark (N.J.) could not be reached – not because of 31 insufficient battery capacity, but because trains would not spend enough time under the wire to 32 recharge. 33 34 35 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 18 PhiladelphiaNorth Broad St.JenkintownLansdaleQuakertown NorristownPottstown West TrentonBound Brook Existing Electrification Battery -Electric TractionPhiladelphia Regional Rail Network Approximate Maximum Extent of Improvements to Range of Current Electrified Service Using Battery Electric Locomotives (BELs) Legend Figure 10 . Philadelphia Rea ding-side case study: extension of existing electrification using BELs (Strategy 3). 1 2 Strategy 4: Use BELs to Create Trans -Regional Services Spanning Electrified Zones 3 Service s in Philadelphia have been through -routed between end points on the former Rea ding 4 and Pennsylvania Railroad (PRR) sides since 1984 . PRR’s e xtensive electrification offers BELs 5 additional charging time. We performed further computations (Methodology B ) and found that 6 longer charging times would enable BELs to reach other key inter-regional markets beyond the 7 normal commutershed . Regional services such as Harrisburg – West Trenton – Newark (N.J.) 8 (H-W-N), Newark (Del.) to Allentown via Lansdale , and New York to Reading via Norristown 9 are technically feasible (Figure 11) . 10 Admitte dly, these services are very speculative . The right -of-way north of Quakertown is 11 today the Bucks County Rail Trail. However, as society works towards reducing GHG 12 emissions, lines now seen as insufficiently promising may come into focus as we look for f urther 13 ways to divert trips from private automobiles . Recent diesel rail planning studies have been 14 conducted for all these corridors (55-57). 15 16 Implementation Issues 17 It might be necessary to reinforce electrical supplies, particularly on the ex -Reading Co mpany 18 (RDG) lines ( 28), to meet the power draw needs of BELs (which could peak at 5.0 MW per 19 pair). 20 Structural engineering studies would determine if all infrastructure elements, particularly 21 the 1992 -1993 replacement for RDG’s 9th Street Viaduct in Nor th Philadelphia, can 22 accommodate the weight of BELs as presently envisioned. Similar questions were previously 23 raised regarding dual -mode equipment ( 55 p. 4). The weight issue might also involve the 24 elevated structure in Manayunk, between Philadelphia an d Norristown . If so, this segment could 25 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 19 be bypassed by diverting trains onto a freight line and an industrial track paralleling the elevated 1 structure. Again, further study would establish what might be needed . 2 3 4 PhiladelphiaHarrisburg West TrentonBound BrookNewark, N.J. Allentown LansdaleQuakertown Norris - townPottstownReading Newark, Del.ThorndaleExisting Electrification Battery -Electric TractionLegend Harrisburg -Newark, N.J. Newark, Del. -Allentown New York -Reading Trenton Mid-Atlantic Inter -Regional Rail Network Possibilities for Electrified Services Utilizing Dual 4.8 MWh Battery Electric Locomotives (BELs) in Push -Pull ConfigurationZOO TowerWayne Jct . Figure 11. Mid -Atlantic Inter -Regiona l rail network showing BEL service s (Strategy 4). 5 6 While RDG’s 9th Street Viaduct was being rebuilt, diesel trains were operated via freight 7 lines from Wayne Junction to the lower (Amtrak) level of 30th Street Station, Philadelphia via 8 Zoo interlocking (54 pp. 76 -79). This would not work for commuter service (Strategy 3) 9 because there would not be enough charging time under the wires (although electrifying one of 10 the tracks between Wayne Junction and Belmont for the use of BELs might make this workable) . 11 For inter -regional services (Strategy 4), this route could be revived by reinstating a track 12 connection at Zoo ( 58). 13 Lithium -ion batteries can catch fire due to mechanical abuse like impact and puncture, or 14 electrical abuse such as overcharging ( 59). They can release toxic gases when burned, with the 15 specific compounds released depend ing on battery chemistry ( 60). Certain chemical reactions in 16 battery fires are not yet fully understood. Batteries are normally designed with redundant 17 cooling systems t o prevent chain reactions called “thermal runaways” that can cause fires to burn 18 out of control, and charge management systems to prevent over -voltage conditions ( 61). 19 Special techniques in firefighting are required to control battery fires, which gener ally 20 requires a large volume of water to be sprayed over a long period. The New York City Fire 21 Department, through the U.S. Fire Administration, has promulgated guidance on these 22 techniques ( 62). Although this is a relatively new field, experience from t he automotive sector 23 suggest s that the overall risk of gasoline fires is nearly two orders of magnitude higher than 24 battery fires ( 63, 64 ). Real -world BEL operating experience is necessary to understand the risks 25 and develop best practices. 26 The Center Ci ty Commuter Connection (like other urban tunnels) has special fire 27 protection requirements. The inadequate ventilation of the original design (based on the 28 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 20 assumption that the tunnel would serve electrics only ) currently restricts diesel operations. What 1 restrictions might apply to BELs would have yet to be determined, although we assume for this 2 strategy that BELs could be operated through the tunnel. 3 Matters of this nature are commonly associated with adopting new technologies. With 4 the right incentiv es, sponsors, operators, and vendors will work together to solve them. 5 6 Operational Logistics 7 In addition to jurisdictional and institutional issues, logistical complications also come into play 8 with trans -regional services. H -W-N service will likely be New York -oriented in market terms, 9 but operationally it must be Philadelphia -based unless the Raritan Valley Line ( between Bound 10 Brook and Newark , N.J.) is electrified . Early morning trips to Newark will originate from 11 Philadelphia rather than Harrisburg, which will require a 9.6 MWh BEL set to be fully charged 12 overnight for each train . Advanced operational skills and perhaps computerized dispatching 13 tools are need ed for the movement bureau, to keep track of each BEL and its charge levels, 14 ensur ing that ba tteries are not depleted in service (see also Methodology D, below) . 15 Figure 12 shows an artist’s concept ion of inter -regional BELs operating over existing 16 electrified infrastructure at Wayne Junction, hauling existing coaching stock where the BELs are 17 serving as a drop -in replacement for what once might have been envisioned as a diesel service . 18 Existing electric multiple -units will continue to provide most commuter services . 19 20 21 22 23 Figure 1 2. Medium -distance battery -electric trainset operating over existin g electrification infrastructure in the 24 Philadelphia area alongside a local electric multiple unit ; artist’s concept by J ohn G. Allen. 25 26 27 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 21 BELs need not charge up only on catenary segment s owned by their service sponsor s. 1 Trans -regional services transcend jurisdictional boundaries and are conceptually designed for 2 BELs to have enough range to make services feasible. Agreements will be needed for electric 3 power charges, perhaps with auditable net -use meters on BELs that show whose units are 4 consuming how mu ch power on which railroad, where, when, and for what purpose (e.g., 5 propulsion, battery charging, or regenerati ng power to the wires ). Back offices would then settle 6 the charges via billing mechanisms like those for trackage rights , mechanical assistance , and 7 equipment leases. 8 9 Strategy 5: Take Advantage of Co -Located Infrastructure 10 Strateg y 2 work s well for Boston Northside . But what about larger systems like Chicago’s, 11 where the distances between downtown terminals and most outer yards exceed the reach of a 12 downtown substation? 13 To explore this issue, we first sought to prioritize lines in terms of their 20 18 ridership, 14 and then follow ed the supply -based strategy to situate substations for maximum coverage. Line- 15 level data on ridership and passenger -miles are shown in Figure 14( A-B). Table 5 ranks 16 Chicago’s commuter lines by ridership intensity (millions of passenger -miles per route -mile) to 17 identify promising opportunities. For comparison, Table 5 also includes the Electric District 18 (electrified by the Illinois Central ). 19 20 21 (A) Chicago % of ridership by line and by mile (B) Chicago ridership count by line and by mile Figure 14. Commuter rail ridership statistics for Chicago showing visualization by line, station, and mileage , emphasizing lines selected for partial electrification case study. Source: Metra Division of Strategic Capital Planning ( 65 pp. 44, 47 -49, 66). 22 23 24 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 22 1 Table 5. Basic 2018 -2019 data for evaluating Chicago electrification possibilities. 2 3 4 Line (Outer End) Million Annual Passe nger Trips Million Annual Passenger Miles Line -Miles Average Trip Length (Mi) Ridership Intensity (A) BN (Aurora) 15.5 363.5 37.5 23.3 9.69 CNW West (Elburn) 8.0 178.2 43.6 22.2 4.09 CNW Northwest (Harvard) 10.5 259.8 70.5 (B) 24.7 3.69 Milwaukee West (Elgin) 6.0 145.4 39.8 24.2 3.65 Electric District (University Park) (C) 7.4 143.5 40.6 (D) 19.3 (E) 3.54 Rock Island District (Joliet) 7.4 147.9 46.6 (F) 21.2 (G) 3.18 Milwaukee North (Fox Lake) 6.5 143.7 49.5 22.8 3.03 CNW North (Kenosha, WI) 8.5 141.5 51.6 16.5 2.74 South West Service (Manhattan) 2.3 44.7 40.8 18.7 1.10 North Central Service (Antioch) 1.6 50.1 52.4 31.2 0.96 Heritage Corridor (Joliet) 0.7 19.7 37.4 27.2 0.53 5 Notes: BN = Burlington Northern. Milwaukee = ex -Chicago, Milwaukee, S t. Paul & Pacific. CNW = Chicago & 6 North Western. A – Millions of annual passenger -miles divided by line -miles. B – Includes 63.1 miles on the main 7 line and 7.0 miles on the McHenry Branch. C – Electrified since 1926. D – Includes the South Chicago an d Blue 8 Island branches. E – This average includes shorter trips on the Electric District’s two branches as well as the main 9 line. F – Includes the Beverly branch. G – This figure, published by Metra, probably accounts for the average trip 10 length on the main line only, i.e., without the Beverly Branch. With the Beverly Branch, the average trip length is 11 19.9 miles. 12 Source: (65 pp. 44, 47 -49) 13 14 15 Burlington Northern (BN)’s Chicago –Aurora line (the first in Table 5 ) jumps to the fore, 16 not simply because i t is Chicago’s busiest line, but also because it has the most passenger -miles 17 and stands far above all others in ridership intensity. This 37.5 -mi line carries about as many 18 riders as Caltrain does between San Francisco and Tamien, just beyond San Jose, C alifornia —a 19 52-mi line being electrified at this writing with two supply substations. A suburb southwest of 20 Aurora has long sought an extension of service, despite being outside the commuter rail agency’s 21 service area. 22 Given the intensive Chicago –Auror a ridership, we sought to electrify the entire line with 23 a single substation, enabling service with e lectric multiple -units (EMUs). Figure 15 shows an 24 artist’s conception of bi -level alternating -current EMUs operating on the Burlington Northern, 25 with long pantographs to support shared -track operations with double -stack container trains. 26 27 28 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 23 1 2 Figure 15. Bilevel gallery electric MU cars operating on electrified infrastructure with clearances for double -stack 3 container trains in Chicago; artist’s concept by John G. Allen. 4 5 6 From there, we looked for other opportunities . Not far away lies the Chicago & North 7 Western (CNW) West Line . Could we power both from the same substation? 8 As it turns out, the maximum range of 25kV catenary allows one substation to serve both 9 lines. A 138kV transmission line runs parallel to the Tri -State Tollway (Interstate 294) in 10 Elmhurst, Illinois (67). Putting a substation on a water -authority property (East Harrison St., 11 Elmhurst) along the transmission line could provide 25k V power to both the Chicago and Aurora 12 ends of the line ( Figure 16 ), for 53,655 weekday trips (Table 6 and Figure 17). Of course, such a 13 strategy would require negotiating an access agreement and lease with the utility company 14 (comparable to a trackage ri ghts agreement between railroads) and an intergovernmental 15 agreement with the water authority. It is a fortuitous coincidence that the CNW West is the 16 second most intensively traveled line in the system, but it was chosen not for its ridership but for 17 its geographic ease of electrification . 18 19 20 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 24 Figure 16 . Chicagoland North and West c ase study, first phase: Elmhurst substation and suburban utility corridors. 1 2 Table 6. Electrification performance metrics for Chicago land North and West case study. 3 4 Seq. Line Weekday Ridership Ridership Receiving Electric Service % Electric % BEL % Shuttle Line Length (Miles) Miles Electrified % Electrified 1 BN (Aurora) 53,655 53,655 100% 0% 0% 37.5 37.5 100% 2 CNW West 26,821 22,284 83% 17% 0% 43.6 29.8 68% 3 CNW Nor thwest 34,993 27,716 79% 21% 0% 63.1 31.9 51% 4 Milwaukee North 21,156 16,259 77% 23% 0% 49.5 32.3 65% 5 Milwaukee West 19,944 18,581 93% 0% 7% 39.8 36.6 92% 6 North Central 5,792 1,334 23% 77% 0% 49.5 32.3 52% Total Chicago 162,361 139,829 86% 13% 0.8% 286.3 195.3 68% 5 6 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 25 05,00010,00015,00020,00025,00030,00035,00040,00045,00050,00055,000 0 10 20 30 40 50 60Weekday Ridership Miles from Downtown T erminalMiles from Downtown vs Ridership Receiving Electrified Service (Chicago) North Central Milwaukee West Milwaukee North CNW Northwest CNW West BN (Aurora) Electrified ZoneBEL Zone Figure 17. Distance -ridership relationship for Chicago North and West case study. 1 2 For the CNW West, electrification could reach beyond West Chicago, but not as far as 3 the next equipment yard at Elburn. Thus, straight electric s would operate as far as West Chicago 4 (22,284 weekday trips, 83% of total ridership) and BELs to Elburn (4,537 trips, 17%). Thanks to 5 existing utility corridors along the highway, it would be relatively straightforward to add an 6 electrical feeder to reac h both rail lines. We verified that BELs would have sufficient range to 7 reach Elburn Yard using the energy assessment model noted previously (Methodology B). 8 Based on this electrification plan, it might be desirable to operate more frequent local 9 service in the electrified zone, with BEL express trains that skip some stops traveling beyond. 10 This is a normal part of schedule re -casting in response to capital investment. BEL trains may 11 carry passengers locally within the electric zone based on ridership n eeds, much as New York’s 12 Wassaic or New Jersey’s Bay Head trains do. 13 14 Suburban Utility Corridors 15 Utility corridors are reasonably common throughout North American metropolitan areas, but 16 because they are not rail facilities, they are not always obvious sol utions for commuter rail 17 electrification. However, by routing railw ay-owned power lines within existing utility corridors, 18 rail networks may be electrified at lower cost than by constructing substations for each line 19 separately. The Department of Homelan d Security has a geographic dataset showing most high 20 voltage transmission lines and corridors in the United States ( 67). 21 Expanding on this approach, it may be possible to co -locate a supply substation near 22 Deval, a crossing between CNW’s Techny Cutoff fr eight line , CNW Northwest, and the North 23 Central Service (NCS ). The CNW Northwest is the third most intensively used line in the 24 system and lies directly on the proposed Deval substation, making it an obvious candidate for 25 electrification. We propose ele ctrifying the CNW Northwest as far as Barrington, a major 26 equipment storage point. BELs can operate beyond there in battery mode . 27 Deval is also served by existing 138kV transmission lines and utility corridors ( Figure 28 18). What else can be electrified f rom Deval? The nearest major line is the Milwaukee North , 29 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 26 which can be readily electrified to Rondout , north of Lake Forest, where space is available to site 1 a yard (there is only one existing yard at Fox Lake, the outer end of the line ). These core 2 subu rban markets on the CNW Northwest and the Milwaukee North would receive straight - 3 electric service (77% and 79% of line ridership respectively), with one -seat rides to the outer 4 suburban areas using BELs. The link between Deval and the Milwaukee -North uses an existing 5 utility corridor that intersects the line in Morton Grove. 6 7 8 9 10 Figure 18 . Deval Crossing, seen from a North Central Service train just north of the CNW Northwest Line , 1990, 11 David Wilson photo (CC BY 2.0). 12 13 14 Figure 19 shows an artist’s co ncept of a combination of an outer -suburban BEL -hauled 15 train and inner -suburban EMUs operating on the CNW -Northwest Line near downtown Chicago 16 (note the left -hand running characteristic of CNW ). 17 18 Powering Additional Lines and Improving Resiliency 19 But the electrification opportunities involving Deval do not end with just those two lines . We 20 can supply the Milwaukee West Line as far as Elgin, including the equipment storage yard, 21 although not necessarily the remaining 3.2 miles to Big Timber. This was unf ortunate, as the 7% 22 ridership at Big Timber would have to be served by a battery -EMU shuttle. However, if a future 23 regional service was developed, it might be possible to serve Big Timber with regional BEL 24 trains (see Strategy 6) . 25 26 27 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 27 1 2 Figure 19. Metra BELs pushing a rush -hour outer suburban express on the CNW -Northwest Line, passing an inner 3 suburban EMU; artist’s concept by John G. Allen. 4 5 6 We electrified the Milwaukee West aggressively, even though it has less slightly less 7 ridership than the Milwau kee North , because it has no intermediate yards nor an obvious location 8 for adding one . To have any electric service requires electrification to the outer -end yard at 9 Elgin (an important destination in its own right). 10 Alternatively, depending on the fi ndings of electrical engineering studies, the 11 electrification range might be increased slightly, either by allowing a larger than normal voltage 12 drop or marginally increasing the line voltage. The link from Deval to the Milwaukee West 13 follows the existing Techny Cutoff railroad alignment. The link between the Elmhurst substation 14 and the Milwaukee West uses Interstate 294 and an existing railroad between two major freight 15 yards. 16 By having the electrification system’s two primary substations on a “ring” ar ound the 17 metropolitan area, it provides a level of resiliency unavailable with other designs. Should one 18 supply substation drop out for any reason, it may be feasible to supply all lines from the other 19 substation through a cross -feed, perhaps subject to p ower reduction orders. This would need to 20 be confirmed by detailed design calculations. 21 BN and Milwaukee West aside, the other lines have or could readily have intermediate 22 yards, with sufficiently strong ridership beyond there to warrant BEL services di rectly from 23 downtown. This allowed us to save significant catenary mileage. Because a combination of 24 existing transmission lines and BN’s particularly intensive ridership drove the substation location 25 process, there was no obvious way to move the substat ion outward a few miles to accommodate 26 the Milwaukee West all the way to Big Timber. Further study may suggest other locations that 27 satisf y all other constraints while comfortably powering the entire Milwaukee West. 28 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 28 Having added Milwaukee West, it now ma kes sense to electrify the North Central Service 1 (even though Table 5 ranks it next to last in ridership intensity ) to Wheeling, based on daily 2 diesel train -miles (DDTM) eliminated. From Wheeling, BELs can reach the outer terminal at 3 Antioch. Although the NCS has a lower ridership density than the other lines , it shares tracks 4 with the Milwaukee West between Tower B -12 and downtown, which in fact gives the NCS the 5 highest electrification productivity of the six lines in terms of DDTM eliminated per catena ry 6 track -mile (Table 7). With just two substations, we can electrify one line fully, and most of five 7 others, with much greater economy of investment than if we tried to electrify these lines in their 8 entirety . 9 This demonstrates the network effect, where it becomes cheaper to add light -density 10 branches (which would otherwise never justify electric service) to an existing network, if most 11 lines are already electrified. Indeed, this may be Boston’s strategy with the planned Fairmount 12 Line electrification, by connecting new catenary to the Northeast Corridor’s existing Sharon , 13 Massachusetts supply substation . 14 15 16 Table 7. Comparative electrification productivity at line level , Chicago North and West. 17 18 Seq. Line Technology Catenary Miles (CM) † 2019 Weekday Trains Daily Diesel Train Miles (DDTM)* Productivity (DDTM per CM) 1 BN (Aurora) Straight Electric 113.3 97 3,022 26.7 2 CNW West (Elburn) Battery -Electric 93.1 59 2,434 26.1 3 CNW Northwest (Harvard) Battery -Electric 92.5 65 3,047 32.9 4 Milwaukee No rth (Fox Lake) Battery -Electric 70.0 63 2,549 36.4 5 Milwaukee West (Elgin) Straight Electric 70.0 58 1,936 27.7 6 North Central (Antioch) Battery -Electric 27.5 22 1,162 42.3 19 Notes: Excludes deadhead mileage. † - Estimated from track charts found at ( 68). Excludes Chicago terminals and 20 equipment storage yards. * - Estimated based on publicly available information. 21 Source: 2019 weekday trains from ( 69). 22 23 24 Table 8 shows our working service plan assumptions for all six lines in the Chicago 25 North and West case study. At first, electric locomotives in push -pull mode would be used to 26 provide service with existing coaches , but depending on the ir remaining useful service life, 27 EMU s may eventually replace them on the BN Line and on inner -suburban segments elsewhere 28 with high ridership densit ies. Figure 20 shows all the lines to be electrified , with supply 29 substation and feeder line locations . 30 31 32 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 29 1 Table 8. Operating and service plan details for Chicago North and West case study . 2 3 Line Service Plan BN (A urora) Replace current diesels with electric locomotives. As coaches becomes life -expired, replace them with EMUs. Recast schedules to take advantage of better capabilities of electric locomotives and/or EMUs. CNW West (Elburn) Electric locomotives with existing coaches will be assigned to do the bulk of the work between West Chicago and downtown. Schedules would be regularized as necessary. The remaining demand west of West Chicago will be carried by BEL expresses, with expresses stopping at busier st ations within the electric zone as appropriate to optimize use of carrying capacity. Milwaukee West (Elgin) All trains replaced by electric locomotive -hauled trains, terminating one stop short at Elgin rather than Big Timber. Trains at Elgin are met by b attery -electric multiple -unit shuttles from Big Timber with passengers making cross -platform transfers. No BELs used on this line. Shuttles are charged whilst stabled between runs at Elgin. CNW Northwest (Harvard) BELs will provide important express tri ps from Harvard and McHenry. Electric locomotives will operate local trips as far as Barrington. Electric trains to be stored on the mainline between Palatine and Barrington as diesel trains do at present. Milwaukee North (Fox Lake) BEL expresses will provide important express trips from Fox Lake. Electric trains will terminate at Lake Forest and be stored in a new yard at Rondout. If there is insufficient ridership to justify any separate off -peak local service, the BEL trains will make all local sto ps. North Central (Antioch) BEL trains to make all current diesel trips between Antioch and Chicago. 4 5 Fox Lake McHenry Rondout Morton GroveHarvard Barrington Big Timber Elgin ElburnWest Chicago Aurora HighlandsBerkeleyBensenville ChicagoCNW -WestElectric Service Battery -Electric ServiceLegend Battery EMU Service Future BEL Service Railway Power Line To Rockford Deval S.S. Harrison St. S.S. (26 miles from Harrison S.S.)(26 miles from Harrison S.S.) (26 miles from Deval S.S.)9050 Lehigh Ave. (16 miles from Harrison S.S.) (17 miles from Deval S.S.)(23 miles from Deval S.S.) (14 miles from Deval S.S.)To Milwaukee Antioch WheelingElmhurst S.S.Elmhurst Elmhurst Elmhurst Figure 20 . Chicag oland North and West c ase study, second phase : feasible extent of electrification from two supply substations. 6 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 30 1 Strategy 6: Char ging Pads 2 Another option is to build “charging pads” at outlying terminals to charge batteries during 3 layover periods, further reducing the track mileage requiring electrification. This makes sense 4 when suitable transmission substations are relatively clo se to outlying yards, such that one or two 5 dedicated 11.3kV three -phase distribution circuits can be brought in to provide 3.0/6.0 MW of 6 charging capacity. Charging pads can also extend an existing installation’s effective range , at the 7 expense of reducin g trainset utilization due to the unproductive downtime when sets are held to 8 charge at rest . 9 One possible use case for a charging pad is where BELs are used on commuter lines with 10 no weekend service . Fairly substantial shore -power supplies would be requ ired to keep head -end 11 power (HEP) on in the coaches during weekend layovers (to avoid draining power from the 12 BEL ). In terms of power rating, shore -supplies required for several stabled sets can be 13 comparable to a charging pad. Figure 21 summarizes situa tions where charging pads are and are 14 not needed for trains worked on a commuter rail service pattern. 15 16 17 7 0 45-mile route, 25 miles electrified, supply substation at MP 1: no charging pad needed. 70-mile route, 40 miles electrified, supply substation at MP 21: no pad needed. 95-mile route, 50 miles electrified, two supply substations: no pad needed. 70-mile route, 25 miles electrified, supply substation at MP 1: need charging pad to extend range of BELs to end of line. A charging pad is equivalent to a very short electrified segment tied to an additional substation.4 5 7 00 1 02 03 04 05 06 08 09 0 Figure 21. Suitability of charging pads with BELs in commuter service . 18 19 Charging pads are most likely to find their ideal applications in region al services that 20 extend beyond the normal daily commutershed, where the distances involved mean that 21 locomotives cannot make an out -and-back trip on one charge, but the service does not terminate 22 in a large metropolis with its own commuter rail system that justifies its own electrification. In 23 busy suburban service, which is the subject of this paper, it is almost always better to extend the 24 electrification marginally beyond the current terminus, to avoid fragmenting the network and 25 avoid having to constru ct an expensive substation purely for supplying a charging pad, when the 26 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 31 budget for that substation could be better invested in incrementally extending the existing 1 electrified network, which will have a higher expected utilization. 2 3 Potential Application s to Regional Services 4 Logistical arrangement s from regional services are different from suburban services; it may be 5 necessa ry to supply fully -charged BELs prior to departure, necessitating extended turnaround 6 times at both the city end and the outer termi nus. Two fully -charged 4.8 MWh BELs with 350 7 tons of trailing load traversing average terrain with average curvature will have a range of about 8 200 miles, but to avoid stranding passengers the useful range is likely to be capped at 120 miles 9 by operations management. 10 Table 9 shows some rules -of-thumb for planning purposes as to when charging pads will 11 be needed when planning BEL -hauled services , although because BELs’ actual range can be 12 sensitive to terrain, curvature, and payload, plans made based on these criteri a should be subject 13 to further verification (using Methodology B, below). 14 15 16 Table 9. Rules of thumb for planning operating ranges of BEL -enabled services 17 18 Service Type Trainset Utilization Pattern Charging Pad at the Outer End? Miles Operated Under the Wires Maximum Range of BELs Beyond Electrification Limits * Maximum Range of Train Service Commuter Trainsets operate in out-and-back service with minimal turnaround time at each terminal No n Miles n Miles , or 60 Miles, whichever is lower 2n Miles, or n+60 Miles, whichever is lower Commuter Trainsets operate in-and-back -out service with minimal turnaround time at the city terminal, held to charge at the outer end to ensure sufficient energy to reach the limits of electrification Yes n Miles 2n Miles, or 120 Miles, whichever is lower 3n Miles, or n+120 Miles, whichever is lower Regional Sets held at city terminal or utilized in electric shuttle service to provide a full charge (9.6 MWh) when outbound trains leave electrified section , and are turned immediately at the outer end No n Miles 60 Miles n+60 Miles Regional Sets held to provide a full charge (9.6 MWh) upon exiting electrified section and again before leaving charging pad Yes n Miles 120 Miles n+120 Miles Inter - Regional * Sets he ld or interlined to provide a full charge (9.6 MWh) when leaving both electrified sections N/A† (m+n) Miles 120 Miles (m+n) +120 Miles 19 Note s: This table takes a conservative view of energy adequacy, meaning that a passenger train stranded with an 20 out-of-energy BEL is considered a major operating exception. Where the authority desires to take more operati ng 21 risks, the full -charge range can be extended to 90 miles and 180 miles respectively . 22 *Applies where there is electrified commuter service at both e nds of the route . †A charging pad need not be 23 provided when both urban ends of the service have commuter -based electrification (i.e. Strategy 4). m=Applies to 24 inter-regional services with commuter electrifications at both ends, with m representing the el ectrified line -miles at 25 the city not covered by the variable n. n=Number of electrified line -miles at the city end . 26 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 32 1 2 We performed no modelling to verify these use cases, but below are some random 3 examples of potential markets for charging pad -enabled re gional services. Charging pads are of 4 limited help for commuter services because of the need for short turnaround times at the termini. 5 6  New Haven, Connecticut —Greenfield, Massachusetts: 100 miles —To eliminate the 7 GHGs associated with this existing diesel -operated service (which has been extended 8 north of Springfield, Massachusetts), BELs can be charged on the existing electrification 9 at New Haven and a new charging pad at Greenfield during layovers. 10  Pittsburgh —Greensburg —Altoona, Pennsylvania: 114 miles —the first 24 of which 11 would be subject to Strategy 2 electrification. Regional trains would run the remaining 12 90 miles in battery mode and recharge at the Altoona charging pad. BELs would also be 13 used in commuter service to reach Greensburg and Latrobe (3 1 and 40 miles, 14 respectively, from Pittsburgh). 15 16 17 Chicago North and West Regional Service 18 In Strategy 5, we electrified the Milwaukee District as far as Rondout and Elgin, the maximum 19 prudent extent based on two supply substations located in suburban Chi cago required to support 20 commuter service. If we assumed regional service patterns of trainset utilization, how much 21 further can we push out the service and what other infrastructure would we need to support 22 them? 23 Figure 22 shows a summary of what servic es are possible. Rondout is 32 miles from 24 Chicago Union Station (CUS) . The remaining 54 miles to Milwaukee can be covered on a 25 round -trip basis by fully charged BEL s leaving the electrified district northbound at Rondout. 26 By operating the equipment strictly on an out -and-back basis , we find that the regional service to 27 Milwaukee is possible without any additional infrastructure. However, if service was extended 28 the 70 miles beyond Milwaukee to Fond du Lac, Wisc ., it would be necessary to install a 29 charg ing pad there, because the 124 miles between Rondout and Fond du Lac is at the upper 30 limit of a one -way trip with fully -charged BEL s. Similarly, Madison is 107 miles from Rondout. 31 A charging pad at Madison would enable service (artist’s concept, Figure 2 3) to be operated to 32 and from Chicago via Rondout. 33 34 35 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 33 ChicagoRondout ElginJanesvilleMilwaukeeMadison (32 miles) (37 miles)(54 miles) (40 miles) (67 miles) (34 miles) (50 miles)Rockford Commuter Electrification Regional ElectrificationLegend Regional BEL ServiceChicago North and West Regional Rail Network Approximate Range of Battery Electric Services with Charging Pad or Short Electrified Segment at Madison Deval S.S.Madison S.S.(70 miles to Fond du Lac, Wisc .) 1 2 Figure 22 . Chicago land North and West case study, regional rail phase : feasible extent of electrification from 3 existing regional rail electrification and one or two charging pads. 4 5 6 7 8 Figure 23 . A battery -electric trainset leaves downtown Madison en route to Chicago. Artist’s concept by John G. 9 Allen. 10 11 12 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 34 Elgin is 37 miles from CUS. The remaining 50 miles to Rockford can also be covered by 1 BELs on a round -trip basis. However, a string of municipal ities in the Rock River Valley 2 between Rockford and Janesville may also desire service to Chicago. To provide service on that 3 corridor, it would be necessary to operate the train to Janesville via Rockford. At that point, the 4 train is 85 miles from Elgin and unable to return to Chicago on a round -trip basis. It is therefore 5 necessary to operate the service to Madison, to use the charging pad. 6 A side effect of the infrastructure design is thus that Madison -Janesville segment receives 7 a higher frequency of service. Based on the ridership patterns, it is quite possible that at least 8 some of the service will short -turn at Rockford (via Elgin). To further improve trainset 9 utilization, we could use the BEL sets to run commuter round trips to/from Elgin or Rondout 10 during the time when they would otherwise be held at CUS for charging. 11 12 13 “Twin Cities to Twin Ports” Regional Service 14 How far can we really go with the judicious use of charging pads? Minneapolis -St. Paul has a 15 relatively small Metropolitan Statis tical Area population (3.69 million as of the 2020 Census ), 16 but it does have one commuter rail line between Target Field in downtown Minneapolis and Big 17 Lake, Minn esota . Local plans call for an extension to St. Cloud in the future. If we assume a 18 Strateg y 5 electrification in the Twin Cities, what services can we run in conjunction with 19 Strategy 6? 20 St. Cloud is 59 miles from Coon Rapids, which is 13 miles from Minneapolis. 21 Minneapolis is a further 12 miles from St. Paul. If we treat the St. Cloud servi ce as a regional 22 train, where we ensure the BELs are fully charged before leaving downtown, it is actually 23 possible to run this service out -and-back between St. Paul and St. Cloud. We could also operate 24 every other trip as a Coon Rapids shuttle, which wou ld double the service frequency on the 25 busiest segment of the line between there and St. Paul and, allow the trainset to earn revenue 26 whilst charging. 27 Duluth is 140 miles from Coon Rapids, which is too far for the current BELs even if we 28 install a chargin g pad there. However, if we situate the substation required for Strategy 5 29 electrification in Coon Rapids, we can electrify a further 21 miles between there and Athens, 30 Minn. This would allow the regional BEL service to run the 119 miles to reach the cha rging pad 31 in Duluth. 32 Thus, in this case, we will have completely electrified an Eastern Minnesota suburban 33 and regional rail network with just two substations, and 44 miles of catenary (Figure 24): 34 Athens -Coon Rapids (21 miles) for the regional service, C oon Rapids -St. Paul (21 miles) for the 35 commuter service, and a two -mile spur between Minneapolis Junction (Harrison St.) and Target 36 Field. BELs are extremely infrastructure -efficient in low -density area s such as this (see 37 Methodology E, below) . 38 39 40 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 35 St. PaulMinneapolisCoon RapidsAthensSt. CloudSuperiorDuluth Eastern Minnesota Regional Rail Network Approximate Range of Battery Electric Services with Charging Pad or Short Electrified Segment near Duluth Commuter Electrification Regional ElectrificationLegend Regional BEL Service (21 miles) (21 miles + 2 mile spur)(59 miles)(119 miles) Coon Rapids S.S. Duluth S.S. 1 2 Figur e 24. Eastern Minnesota regional rail network: feasible extent of electrification using a single substation at 3 Coon Rapids and a single charging pad at Duluth. 4 5 6 ANALYTICAL METHODOLO GIES AND RESULTS 7 The f ollowing section provides a technical discussion of the analytical methods used to support 8 the analysis of the six strategies . 9 10 11 Methodology A: Ridership Analysis and Visualization 12 To identify the busiest line segments, we used a visualization technique to plot weekday 13 passenger loads on each line segmen t against mileage s from downtown (Figure s 4 and 1 4). This 14 allows us to visualize how many passengers would travel entirely within the electric zone if we 15 terminated it at a given station , and how many would cross the zone boundary. We also plotted 16 the da ta in percentage terms, because a small number of customers may still be a substantial 17 fraction of total ridership on a given line . 18 In each case we plotted the candidate lines for electrification in colour, and other diesel 19 lines in the same metropolita n area in grey, to establish their relative suitability for BEL -enabled 20 electrification ( e.g., relatively high ridership density), although by no means was ridership the 21 only consideration for inclusion in the case study schemes. 22 Operating considerations such as existing yard locations , combined with substation 23 location and 25kV transmission limits , may ultimately dictate the extent of electrification . But 24 this visuali zation helped us to make decisions about initial substation siting and whether a single 25 centrally -located substation or multiple outlying substations would be best . The key 26 consideration is the distance beyond which demand density falls sharply (if it is within the 25 - 27 mile threshold based on 25kV substation reach) —and whether the demand dens ity/distance 28 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 36 relationship is linear (e.g. Figure 4, Providence Line ; Figure 14, BN -Aurora Line ), or 1 significantly non-linear with plots showing either a characteristic S -shape (e.g. Figure 4, 2 Newburyport/Rockport Lines) , or a classic L -shape (e.g. Figure 1 4, CNW -North Line and South 3 West Service) . Lines whose travel demands are concentrated in the inner suburban portion s are 4 better candidates for partial electrification. 5 These visualizations also helped with choosing between a local battery EMU sh uttle an d 6 a direct BEL train from downtown when developing operating plans . If there is substantial 7 ridership beyond electrification limits, then a direct BEL train is considered. Otherwise, the 8 service is relegated to a connecting shuttle. 9 If the policy goal i s to reduce GHG emissions rather than to improve service or reduce 10 costs , ridership density alone should not drive electrification decisions . Electrification 11 productivity, such as daily diesel train miles per catenary mile shown in Table 7, which is 12 ultim ately a rough proxy for GHG reduction per dollar invested, is a much more useful indicator 13 with which to evaluate proposals . 14 15 Methodology B: Energy Assessment for Service Feasibility and Market Scan 16 This analysis determine s, at a strategic level, how many (existing or proposed) commuter rail 17 corridors could benefit from partial electrification in conjunction with BELs. In selecting 18 corridors to examine, we chose from the following situations: 19 20 1. Existing electrified commuter rail corridors where communities have sought to extend 21 service s beyond existing electrified zone s. This includes situations where services 22 formerly existed . 23 2. Hypothetical new -start electrifications where diesel service s currently exist, but an 24 electrification strategy would reduce GHG em issions. 25 26 Based on each corridor’s basic service characteristics, we computed the minimum time 27 available for charging the two 4.8 MWh locomotive s during a round trip, from entering the (new 28 or existing) electrified zone inbound, to leaving it outbound. Available power leaving electrified 29 territory was based on a combined locomotive capacity of 9.6 MWh (and a C/4 maximum 30 combined charging rate of 2.4 MW). We conservatively assumed that when ever a locomotive 31 was actively accelerating, the battery could not be charged, to avoid exceeding the 4 .0 MW 32 substation limit of typical suburban electrifications. It should be possible to configure the 33 circuitry aboard BELs to prevent recharging while drawing power for traction. 34 Through these calculations, we found BE Ls to be feasible on 32 distinct services in the 35 Boston, New York, Philadelphia, and Chicago areas. Table 10 shows detailed results in terms of 36 battery power, train ascent and descent, rolling, curving, accelerating and braking requirements, 37 parasitic loa ds, charging pad requirements at outer endpoints, energy sufficiency, and capacity 38 for degraded operations. The calculations show the feasibility of operating the various proposed 39 services using BELs under conditions of partial electrification. Interesti ngly, our findings 40 suggest that it should be feasible to use BELs between Boston South Station and Needham, 41 Massachusetts, even though less than half of this route is on the electrified Northeast Corridor . 42 We made reasonable assumptions about typical wors t-case rates of grade, curvature, and 43 other physical characteristics (see notes, Table 10). We normally assumed a worst -case 44 commuter rail consist of two 148 -ton locomotives with seven 135,000 -lb coaches each drawing a 45 parasitic load of 40 kW, although in some cases we scaled back the consist for particularly 46 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 37 curvaceous or long routes. These were fed into aggregate formulas that provide cumulative 1 outputs of a Train Performance Calculator (TPC) without having to simulate each linear foot of 2 track. Trains were generally assumed to run express through the electrified zone, and as locals 3 elsewhere. 4 We separately computed the energy required to lift trains uphill, overcome rolling and 5 curving resistance, and accelerate from station stops, using industry st andard formulas. 6 Additionally, taking maximum battery charging rates and regenerative braking efficiency into 7 account, we calculated energy recoverable from descending grades and braking to station stops. 8 This was not a true TPC exercise, because it was not feasible to collect detailed physical 9 characteristics for all these lines. This methodology should be understood as predicting what a 10 detailed TPC would likely report in the worst case, based on assumptions informed by the 11 authors’ experience. Operat ors studying given networks should undertake detailed TPC and 12 preliminary engineering analyses, during which they can also examine additional options such as 13 electrifying segments other than immediate approaches to the downtown area and consider 14 alternativ e supply substation sites. 15 16 Operating BELs on Legacy Electrification Infrastructure 17 Although the Boston and Chicago cases presume 25kV electrification, we found partial 18 electrification to be feasible with the 12.5kV systems used in much of the Northeast Co rridor, 19 and potentially even with low -voltage third -rail systems. However, the lower the voltage, the 20 more current is needed to provide the same power. Excessive current draw should be avoided so 21 as not to exceed substation and traction return capacity. 22 The desirability of 25kV for new -start electrification – with or without BELs – lies in its 23 greater electrical efficiency. The higher voltage allows railroads to electrify more line -miles 24 with fewer substations. Generally, the lower voltages found on le gacy installations should not 25 affect the feasibility of using BELs, as the Philadelphia -based examples (Strategies 3 and 4) 26 suggest. 27 28 29 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 38 Table 10. Battery -electric locomotive energy assessment model outputs 1 2 Basic Service Characteristics 3 Service End of Service Basic Service Charac teristics ID Line Name Origin Electrification Terminus (A) (B) (C) (D) (E) (F) 1 Hudson New York Harmon Poughkeepsie 33 39 4 10 60 70 2 Harlem New York Brewster Wassaic 53 30 7 7 60 70 3 Danbury New York Norwalk Danbury 40 24 3 7 70 50 4 Waterbury Stamford Devon Waterbury 28 29 3 6 70 40 5 Greenport Penn Station Ronkonkoma Greenport 49 45 7 6 75 45 6 Montauk Penn Station Babylon Speonk 37 34 2 9 75 60 7 Stoughton South Station Canton Jct. Stoughton 15 4 8 2 70 40 8 Needham South Station Forest Hills Needham 5 9 4 8 70 40 9 Franklin [1 1] South Station Readville Franklin 9 21 4 10 70 40 10 Quakertown Philadelphia Lansdale Quakertown 24 16 8 6 40 40 11 West Trenton Philadelphia West Trenton Bound Brook 32 27 8 5 50 60 12 Pottstown Philadelphia Norristown Pottstown 18 23 7 6 40 40 14 Harrisburg/Newark Harrisburg West Trenton Newark NJ 135 52 20 8 60 60 15 Newark/Allentown Newark, Del. Lansdale Allentown 63 37 18 10 60 45 16 Reading/New York Penn Station Norristown Reading 108 41 29 9 80 45 17 Hackettstown Hoboken, N.J. Dover Hackettstown 43 17 4 5 60 45 18 Montclair -Boonton Penn Station Montclair S.U. Dover 24 19 7 8 40 40 19 Jersey Coast Penn Station Long Branch Bay Head 51 16 11 9 60 50 20 Lowell/Manchester North Station Lowell Manchester NH 26 30 7 3 55 50 21 Haverhill via Wildcat North Station Andover Exeter NH 23 27 5 7 45 50 22 Newburyport North Station Salem Newburyport 17 19 6 6 45 50 23 Newburyport North Station Salem Rockport 17 19 6 7 45 50 24 Fitchb urg North Station South Acton Wachusett 25 28 9 6 40 45 25 Middleboro/Lakeville South Station Randolph Middleborough 15 21 5 10 45 45 26 Plymouth/Kingston [1 2] South Station S. Weymouth Plymouth 16 21 5 8 45 45 27 Greenbush South Station Wey. Landing Greenbush 12 17 3 9 45 45 28 CNW -West CNW Station West Chicago Elburn 30 14 14 4 60 60 29 CNW -Northwest CNW Station Barrington Harvard 32 31 15 7 60 60 30 CNW -Northwest CNW Station Barrington McHenry 32 19 15 5 60 55 31 MILW -North Union Station Lake Fore st Fox Lake 28 21 14 8 60 55 32 North Central Service Union Station Wheeling Antioch 27 26 9 9 60 50 4 Columns: (A) = Miles Electrified [1]; (B) = Miles Diesel [ 1]; (C) = Stations Electrified [2]; (D) = Stations Diesel 5 [3]; (E) = Speed in Electrified Terr itory (mph); (F) = Speed Diesel Zone (mph); 6 7 Assumptions: [1] Electric mileage is always rounded down, and diesel mileage rounded up, to provide a worst -case 8 scenario estimate; [2] Assumes a service pattern that may or may not currently exist, of a skip -stop express in the 9 inner suburban portion of the route; [ 3] Reasonable assumptions about station stops made in portions of the line 10 currently has no direct service; [1 1] Assuming service operated via the NEC with appropriate arrangements at 11 Readville; [1 2] Includes two -way s witching movement to and from coach yard. 12 13 Geography Key: (1)-(6) = Greater New York; (7) -(9) = Boston Southside Existing Installations; (10) -(12) 14 Philadelphia Regional Rail; (14) -(16) Inter -Regional Rail Northeast; (17) -(19) = New Jersey ; (20) -(24) Boston 15 Northside Strategy 2 electrification; (25) -(27) Boston Old Colony Strategy 2 electrification; (28) -(32) Chicago North 16 and West Strategy 5 electrification. CNW = Chicago & North Western . 17 18 19 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 39 Table 10. Battery -electric locomotive energy assessment model outputs (continued) 1 2 Available Battery Power, Coach Weight, Ascent and Descent Energy Requirement Calculations 3 Avail able Battery Power Calcula tions Tons Climb ing and Descent Energy Calcula tions ID (G) (H) (J) (K) (L) (M) (N) (P) (Q) (R) (S) (T) (U) (V) 1 0:39 0:04 0:20 1:47 4.29 N 350 200 350 15.6 802 -1.0 100% -272 2 1:03 0:07 0:20 2:41 6.45 N 350 475 833 12.0 617 -3.1 76% -494 3 0:41 0:03 0:20 1:48 4.33 N 350 380 666 9.6 691 -2.2 100% -517 4 0:28 0:03 0:30 1:33 3.74 N 350 459 805 11.6 1,044 -1.8 100% -625 5 0:47 0:07 0:20 2:08 5.12 N 338 300 516 18.0 1,440 -0.8 100% -400 6 0:35 0:02 1:00 2:15 5.40 N 405 200 380 13.6 816 -1.1 100% -295 7 0:15 0:08 0:20 1:06 2.67 N 473 63 132 1.6 144 -2.1 100% -102 8 0:05 0:04 0:20 0:38 1.53 N 473 143 297 3.6 324 -2.1 100% -231 9 0:09 0:04 0:20 0:46 1.86 N 350 333 583 8.4 756 -1.8 100% -452 10 0:43 0:08 0:20 2:02 4.90 N 473 253 528 6.4 576 -2.1 100% -410 11 0:46 0:08 0:20 2:08 5.13 N 473 428 892 10.8 648 -3.2 75% -518 12 0:32 0:07 0:20 1:38 3.95 N 473 364 759 9.2 828 -2.1 100% -589 14 2:42 0:20 0:05 6:09 9.60 Y 350 819 1,435 20.7 1,241 -2.7 89% -993 15 1:15 0:18 0:05 3:11 7.66 N 350 584 1,024 14.8 1,181 -2.0 100% -795 16 1:36 0:29 0:05 4:16 9.60 Y 350 653 1,144 16.5 1,318 -2.0 100% -887 17 0:51 0:04 0:30 2:21 5.65 N 473 269 561 6.8 544 -2.4 100% -435 18 0:43 0:07 0:20 2:00 4.82 N 473 301 627 7.6 684 -2.1 100% -487 19 1:01 0:11 0:20 2:44 6.58 N 473 75 156 6.4 461 -0.8 100% -121 20 0:33 0:07 0:20 1:40 4.03 N 350 475 833 12.0 864 -2.2 100% -646 21 0:36 0:05 0:20 1:43 4.15 N 300 433 700 10.9 787 -2.1 100% -543 22 0:26 0:06 0:20 1:25 3.43 N 350 307 538 7.8 559 -2.2 100% -418 23 0:26 0:06 0:20 1:25 3.43 N 350 293 513 7.4 533 -2.2 100% -398 24 0:45 0:09 0:20 2:09 5.16 N 350 675 1,182 11.4 909 -3.0 79% -727 25 0:24 0:05 0:20 1:18 3.12 N 350 326 572 8.2 659 -2.0 100% -444 26 0:25 0:05 0:20 1:20 3.22 N 350 337 591 8.5 682 -2.0 100% -459 27 0:18 0:03 0:20 1:03 2.55 N 350 274 480 6.9 554 -2.0 100% -373 28 0:35 0:14 0:20 1:59 4.77 N 424 227 442 5.7 343 -3.0 80% -275 29 0:37 0:15 0:20 2:05 5.02 N 424 496 968 12.5 751 -3.0 80% -601 30 0:37 0:15 0:20 2:05 5.02 N 424 295 575 7.4 487 -2.7 87% -390 31 0:33 0:14 0:20 1:55 4.64 N 424 336 655 8.5 555 -2.7 87% -444 32 0:32 0:09 0:20 1:43 4.13 N 424 406 791 10.2 737 -2.5 96% -590 4 Columns: (G) = One -way run time (hh:mm) in electrified zone at maximum authorized speed [ 4]; (H) = Dwell time 5 (hh:mm) at outlying stations [5]; (J) = City terminal minimum equipment dwell time (hh:mm) ; (K) = Available 6 charging time ( hh:mm, round trip); (L) = Available energy entering non -electrified territory (MWh) [ 6]; (M) = 7 Loco motive capacity 9.6 MWh exceeded? (Y/N); (N) = Coach tonnage; (P) = Elevation gain to summit (ft) [ 7]; (Q) 8 = MJ of energy to lift train; (R) = Miles i n descent; (S) = Seconds in descent; (T) = Energy release rate (MJ/s = 9 MW); (U) = % of recapturable energy; (V) = MJ of energy recyclable during descent. 10 11 Assumptions: [4] Time spent accelerating from each station stop is not available for charging batteri es due to 12 concerns about substation loading. Schedule padding = 20%; [ 5] Dwell time per station = 1 minute; [6] Maximum 13 charging rate = 2.4 0 MW = C/4 on a 9.6 MWh locomotive (i.e. 4 hours to charge to 100%), for two 4.8 MWh 14 locomotives the charging rate i s twice 1.2 MW; [ 7] Worst case, assumes a steeply -graded route in the diesel segment 15 (assumed average gradi ent for all uphill segments = 0.30%). This obviously will not be true for every route. 16 Adjusted manually where appropriate; Acceleration due to gravity = 9.81 m/s/s; Dynamic brake efficiency = 97%; 17 Assumed % of mileage in descent = 40%; Gradient variability factor = 3; Assumed cumulative curvature per mile 18 (degrees) = 1.00; Typical achievable braking rate = 1.00 mph/s. 19 20 21 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 40 Table 10. Battery -electric locomotive energy assessment model outputs (continued) 1 2 Rolling, Curving, Acceleration, Braking, Parasitic Load Energy Calculations 3 Rolling Curv ing Accele ration Braking Parasit ic Load Charg ing Pad ID (W) (X) (Y) (Z) (AA) (AB) (AC) (AD) (AE) (AF) (AG) (AH) (AJ) (AK) 1 1,363 15 2,152 284 2,836 -2,751 70 -4.1 59% -1,630 2:36 0.73 Y 1.6 2 1,049 20 2,207 284 1,985 -1,926 70 -4.1 59% -1,141 2:06 0.59 N 0 3 536 24 2,119 145 1,013 -983 50 -2.9 83% -815 2:12 0.62 N 0 4 508 29 3,093 93 556 -539 40 -2.3 100% -539 2:37 0.73 Y 1.6 5 737 20 3,246 115 690 -669 45 -2.6 94% -629 3:10 0.63 N 0 6 888 20 2,714 226 2,035 -1,974 60 -3.8 64% -1,257 2:33 0.61 N 0 7 74 4 70 110 220 -214 40 -2.8 87% -186 1:02 0.29 N 0 8 165 9 354 110 881 -855 40 -2.8 87% -745 1:47 0.50 N 0 9 368 21 1,622 93 926 -898 40 -2.3 100% -898 2:33 0.71 Y 1.6 10 294 16 1,120 110 661 -641 40 -2.8 87% -559 1:58 0.55 N 0 11 789 20 2,363 248 1,239 -1,202 60 -4.1 58% -698 1:59 0.56 N 0 12 423 23 2,315 110 661 -641 40 -2.8 87% -559 2:19 0.65 N 0 14 1,456 30 5,705 208 1,667 -1,617 60 -3.5 69% -1,117 3:03 0.86 N 0 15 731 37 5,008 117 1,172 -1,137 45 -2.6 92% -1,048 3:08 0.88 N 0 16 816 41 6,243 117 1,055 -1,023 45 -2.6 92% -943 3:14 0.91 N 0 17 352 17 1,265 139 697 -676 45 -3.1 77% -524 1:50 0.51 N 0 18 349 19 1,580 110 881 -855 40 -2.8 87% -745 2:17 0.64 N 0 19 373 16 1,120 172 1,549 -1,503 50 -3.4 70% -1,048 2:03 0.58 N 0 20 671 20 2,207 145 434 -421 50 -2.9 83% -349 2:07 0.59 N 0 21 548 27 2,535 134 935 -906 50 -2.7 90% -815 2:20 0.56 N 0 22 434 19 1,384 145 868 -842 50 -2.9 83% -698 1:56 0.54 N 0 23 414 19 1,259 145 1,013 -983 50 -2.9 83% -815 1:59 0.56 N 0 24 563 43 4,450 117 703 -682 45 -2.6 92% -629 2:25 0.68 Y 1.6 25 408 21 1,561 117 1,172 -1,137 45 -2.6 92% -1,048 2:24 0.68 N 0 26 422 21 1,669 117 938 -910 45 -2.6 92% -838 2:16 0.64 N 0 27 343 17 1,101 117 1,055 -1,023 45 -2.6 92% -943 2:11 0.61 N 0 28 412 14 838 232 928 -900 60 -3.9 62% -559 1:28 0.41 N 0 29 901 10 1,282 232 1,625 -1,576 60 -3.9 62% -978 2:17 0.64 N 0 30 479 15 1,143 195 975 -946 55 -3.5 68% -640 1:45 0.49 N 0 31 546 21 1,841 195 1,560 -1,513 55 -3.5 68% -1,024 2:06 0.59 N 0 32 587 20 2,097 161 1,450 -1,407 50 -3.2 74% -1,048 2:26 0.68 N 0 4 5 Columns: (W) = Rolling resistance (MJ) in diesel zone [ 8]; (X) = Worst case cumulative route curvature ( degrees) 6 [9]; (Y) = Curving resistance (MJ) in diesel zone [10]; (Z) = MJ of energy expended per station stop; (AA) = Total 7 MJ of energy expended for acceleration; (AB) = Total MJ of energy released during braking; (AC) = Duration of 8 braking action per stop (seconds); (AD) = Energy release rate (MJ/s = MW); (AE) = % of energy recapturable; (AF) 9 = MJ of energy recyclable during braking; (AG) = Round trip time off -wire; (AH) = Round -trip energy consumed 10 by parasitic loads (MWh); (AJ) = Outer terminal charging pad needed? (Y/N); (AK) = Energy transferred at 11 charging pad (MWh) . 12 13 Assumptions: [8] Modified Davis formula (1970); Defaults: Tons per coach = 67.5 tons; Coach tonnage = 473 tons; 14 Locomotive tonnage = 296 tons (two locomotive s); Axles per train = 36; [9] Manually adjusted where significant 15 differences from typical assumptions are known; Parasitic load per car = 40 kW; Acceleration/deceleration time per 16 station = 1.5 Mins ; [10] AREMA (0.8 lbs per ton per degree); 17 18 19 20 21 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 41 Table 10. Battery -electric locomotive energy assessment model outputs (con cluded) 1 2 Charging Pad, Energy Sufficiency, and Degraded Operations Assessments 3 Energy Suffi ciency Assess ment Degrad ed Oper ations ID (AL) (AM) (AN) (AP) (AQ) (AR) (AS) (AT) (AU) (AV) 1 4.5 -1.0 3.4 2.1 5.49 5.89 Y 4.5 4.3 N 2 4.0 -0.9 3.1 1.9 4.94 6.45 Y 4.0 6.4 Y 3 3.0 -0.7 2.3 1.4 3.70 4.33 Y 3.0 4.3 Y 4 3.5 -0.6 2.9 1.7 4.58 5.34 Y 3.5 3.7 Y 5 3.5 -0.6 3.0 1.8 4.74 5.12 Y 3.5 5.1 Y 6 4.0 -0.8 3.1 1.9 4.99 5.40 Y 4.0 5.4 Y 7 0.6 -0.2 0.4 0.2 0.65 2.67 Y 0.6 2.7 Y 8 1.4 -0.5 0.9 0.6 1.47 1.53 Y 1.4 1.5 Y 9 2.7 -0.7 1.9 1.2 3.09 3.46 Y 2.7 1.9 N 10 2.0 -0.5 1.5 0.9 2.36 4.90 Y 2.0 4.9 Y 11 3.5 -0.7 2.8 1.7 4.54 5.13 Y 3.5 5.1 Y 12 3.0 -0.6 2.3 1.4 3.75 3.95 Y 3.0 4.0 Y 14 6.6 -1.1 5.4 3.3 8.68 9.60 Y 6.6 9.6 Y 15 5.3 -1.0 4.3 2.6 6.88 7.66 Y 5.3 7.7 Y 16 6.1 -1.0 5.1 3.0 8.11 9.60 Y 6.1 9.6 Y 17 2.1 -0.5 1.6 1.0 2.55 5.65 Y 2.1 5.6 Y 18 2.6 -0.7 1.9 1.1 3.02 4.82 Y 2.6 4.8 Y 19 2.4 -0.6 1.7 1.0 2.76 6.58 Y 2.4 6.6 Y 20 2.9 -0.5 2.4 1.4 3.78 4.03 Y 2.9 4.0 Y 21 3.2 -0.7 2.5 1.5 3.92 4.15 Y 3.2 4.2 Y 22 2.3 -0.6 1.7 1.0 2.78 3.43 Y 2.3 3.4 Y 23 2.3 -0.7 1.7 1.0 2.69 3.43 Y 2.3 3.4 Y 24 4.5 -0.7 3.8 2.3 6.06 6.76 Y 4.5 5.2 Y 25 2.7 -0.8 1.9 1.2 3.10 3.12 Y 2.7 3.1 Y 26 2.7 -0.7 2.0 1.2 3.12 3.22 Y 2.7 3.2 Y 27 2.3 -0.7 1.6 0.9 2.49 2.55 Y 2.3 2.6 Y 28 1.9 -0.4 1.4 0.9 2.27 4.77 Y 1.9 4.8 Y 29 3.3 -0.9 2.4 1.5 3.91 5.02 Y 3.3 5.0 Y 30 2.3 -0.6 1.7 1.0 2.72 5.02 Y 2.3 5.0 Y 31 3.1 -0.8 2.4 1.4 3.77 4.64 Y 3.1 4.6 Y 32 3.4 -0.9 2.5 1.5 4.06 4.13 Y 3.4 4.1 Y 4 Columns: (AL) = Round Trip Energy Demand (MWh); (AM) = Round trip 5 recoverable energy (MWh); (AN) = (AL) + (AM) = Net energy requirement 6 (MWh); (AP) = Reserve energy requirement (MWh); (AQ) = Total energy 7 requirement (MWh); (AR) = (L) + (AK) = Available battery power (MWh); (AS) 8 = Is service feasible? (Y/N); (AT) = Energy demand without regeneration (MWh); 9 (AU) = (L) = Energy supply leaving electrified district (MWh); (AV) = Reserves 10 sufficient for degraded operations? (Y/N) 11 12 Assumptions: Battery efficiency = 97%; Battery power reserve requirement factor 13 = 60% (This assumption is a fleet management decision; different operators may 14 have different policies regarding minimum reserve fuel requirements.) 15 16 17 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 42 1 Perhaps counterintuitively , our calculations show BEL operation is feasible on some 2 legacy low -voltage third -rail lines for services where slightly less than half of the distance is 3 electrified. However, in some cases there is a need for either a chargin g pad at the outer end of 4 the line , or short exten sions of existing electrification. The se cases exemplify the tradeoff for 5 longer non -electrified portions where additional infrastructure would be built. Study ing the 6 specific operating needs and infrastr ucture costs on a given line would determine what form this 7 should take . 8 BELs will need to recharge when coming into the electrified zone. As th is need will be 9 the greatest when returning to the outer end of the electrified zone after operating in batter y 10 mode, rail operators will have to pay particular attention to ratings of their existing power 11 supplies in these outer areas. 12 These increased power requirements will need to be recognized and planned for. 13 Existing substations may have to be enhanced a nd/or new ones built to provide the necessary 14 power. Some commuter railroads experienced power shortages when they introduced new, high - 15 performance equipment in the late 20th century without improving power supplies (28). 16 Likewise, operating power -hungry BELs on unimproved legacy electrifications could have 17 reliability consequences unless power needs are addressed . 18 On some branch lines, there was not enough charging time under the wires for off -peak 19 services to be operated as shuttles from the branch jun ction. However, various solutions are 20 possible, such as originating the shuttles from a point further down the mainline, or to provide 21 layover charging facilities near the branch junction. 22 23 Methodology C: Lifecycle Cost Analyses for Financial Feasibilit y 24 The five Boston Northside alternatives ( Table 11(a)) analyzed in the lifecycle cost analysis 25 represent different strategies for how electrification might be addressed. Alternatives (I) and (V) 26 use BELs to provide service beyond a core electrified territ ory representing the minimum 27 electrification necessary to reach the entire service area, with Alternative (I) representing the 28 existing network and Alternative (V) including long -proposed extensions to New Hampshire. 29 Alternatives (II) through (IV) are con ventional electrification solutions that vary in scope, with 30 Alternative (II) not quite covering the entire existing service area due to the maximum feeding 31 distance of 25kV substations. 32 We determined the track -miles of catenary required based on the curr ent track map and 33 determined the number of autotransformer substations required based on their maximum feeding 34 distances. Because interlockings require special catenary work, and may require signal 35 interference immunization, we provided extra scopes of wo rk to account for this. We assume a 36 large supply substation at the Boston Engine Terminal, and other smaller supply substations in 37 outlying areas as needed to meet electrical demands. We made no attempt to determine site - 38 specific conditions or connection s to the electrical grid. Eastern Massachusetts has a 39 comparatively dense transmission grid, and suitable supplies should be available close to where 40 they are required. 41 42 43 44 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 43 Table 11. Hypothetical life cycle cost assessment of commuter rail electrification strategies. 1 2 (a) Infrastructure Characteristics 3 Alt. Description Electrified Track Miles Electrically Operated Track Miles % Operated Under Wire % Operated on Batteries Autotrans - former Subs Required Supply Subs Required (I) Electrification of Existing S ervice Using BELs and One Supply Substation 173.8 291.1 60% 40% 13 1 (II) Maximum Extent of Electrification Using One Supply Substation (Figure 3)* 198.4 198.4 100% 0% 15 1 (III) Electrification of all Existing Services w/ Straight Electrics 291.1 291.1 100% 0% 23 4 (IV) Electrification of all Existing Services plus NH Extensions 348.1 348.1 100% 0% 31 5 (V) Electrification of Existing Services & NH Extensions Using BELs (Figure 6) 173.8 348.1 50% 50% 13 1 4 (b) Capital and Maintenance Cost Assessment 5 Alt. Fleet Required Fleet Type Fleet Cost ($m) Infra - structure Cost ($m) Capital Cost ($m) Electric Traction Dept. Headcount NPV of Ongoing Maint. -of- Way Cost ($m) NPV of Ongoing Loco. Maint. Cost ($m) Total System Cost ($m) Ratio vs Alternative (V) Cost (I) 60 BELs $600 $1,204 $1,804 69 $265 $180 $2,250 94% (II) 24 Electrics $180 $1,359 $1,539 76 $293 $55 $1,887 78% (III) 27 Electrics $203 $2,071 $2,274 125 $485 $62 $2,821 117% (IV) 33 Electrics $248 $2,537 $2,785 153 $594 $76 $3,455 144% (V) 72 BELs $720 $1,204 $1,924 69 $265 $216 $2,406 100% 6 (c) Unit Cost and Labor Productivity Assumptions 7 8 Item Cost ($m) Master Supply Substation 75 Outlying Supply Sub 30 Autotransformer Sub 15 Catenary Cost per Track Mile 3 Catenary Work Cost per Interlocking 7.5 Soft Costs 30% Battery Electric Loco motive Purchase 10 Straight Electric Loco motive Purchase 7.5 Electric Loco motive Midlife Overhaul 0.3 Battery Loco motive Midlife Overhaul 0.5 Battery Loco motive Five-Year Campaign 0.25 Item Value Substations Assigned per Gang 3 Supply Subs Assigned per Gang 0.5 Catenary Miles Assigned per Gang 20 Additional Catenary Miles per Interlocking 1 Employees per Gang 3 Linemen Hourly Rate $40.00 Overtime % 20% Fringe & Benefits Overhead % 80% Effective Annual Rate $194,688 Discount Rate (for NPV) 5% Vacation/Sick Relief Ratio 20% 9 Note s: NPV = Net Present Value 10 * Alternative (II) assumes that no commuter rail service will be provided to some outlying communities that 11 currently receive service. It also re quires new storage yards to be constructed. This would not be acceptable in 12 reality, but is included here for cost comparison purposes and to demonstrate the pure application of Strategy 1. 13 This strategy is similar to that applied in Philadelphia in 1981 when most diesel service was discontinued as the 14 Center City rail t unnel was nearing completion . 15 16 17 18 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 44 Based on these asset counts, we used our estimates of unit costs (Table 11(c)) to 1 determine investment needs. These are based on industry experience and r eviews of typical 2 projects and are broadly consistent with available industry data ( 38, 70). Some costs might seem 3 high at first glance, but one railroad recently spent almost $50 million rebuilding a single AC 4 supply substation that provides power from a 138kV source. A significant portion of the 5 construction costs of 25kV AC electrification is associated with substations, including the utility - 6 side costs of bringing in high -tension lines. 7 Maintenance of Way costing (Table 11(b)) follows established zero -based methodologies 8 (71) based on previously -determined asset counts, with assumptions about headcount budgeting 9 methods, labor rates, and line gang productivity (Table 11(c)) consistent with typical commuter 10 rail practice. OCS installation ( 72), inspect ion, and maintenance, even with constant -tension 11 catenary, will require significant track time and will affect costs. 12 Locomotive cost estimates (Table 11(b)) are based on recent procurements. N ew BEL 13 costs were not available ; however, we made the conser vative assumption that they would be 14 significantly more expensive than freight locomotives, because North American passenger 15 locomotives are a specialty low -production item. One operator paid $8.8 million per unit for 16 dual-mode electric/diesel locomotives in 2020; another paid $12.4 million. We assumed a 17 passenger BEL would cost $10 million. Shop margins for locomotives were set higher for BELs 18 (20%) than for straight electrics (10%). We estimated locomotive maintenance costs from recent 19 experience ( 73), with five -yearly battery overhauls added to BEL maintenance regimes. 20 The results of this analysis are summarized in Figure 9 above. 21 22 Electrification and Legacy Infrastructure Constraints 23 Even where partial electrification and BEL operation do not involve legacy electrification, other 24 legacy infrastructure issues may arise. Railroads will have to examine their track and yard 25 capacities (perhaps with simulation studies) and decide what limitations can be worked around 26 versus committing to infrastructure ex pansions. Signal systems and track circuits will need to be 27 immunized against interference from traction return current. Electric or BEL maintenance shops 28 will need to be constructed or existing shops updated with new tooling. Shore power may be 29 needed where weekend layovers are planned . 30 Overhead clearances need to be analyzed at low bridges and at downtown terminals and 31 their approaches (e.g., Chicago Union Station, Boston North Station) which were not initially 32 designed for electrified operation. Thi s may not be as much of an issue as generally thought. 33 The British Standards used on Network Rail are based on extensive operating experience with 34 25kV , and suggest that with proper design, trains may operate safely under bridges with as little 35 as 10½” be tween the train’s maximum height and the overhead wire ( 20 p. 55 ). This implies that 36 25kV electrification is possible with a 14’6” static height double -deck car if the structure has at 37 least 16’10” of vertical clearance. For structures that are a little lower than that, other techniques 38 have been developed, notably in Scotland, where Clyde Electric trains coast through short 39 neutral sections under bridges having some very restrictive vertical clearances. 40 There are various options for improving clearances in restricted -space settings. 41 Undercutting the roadbed or installing slab track can provide additional room overhead. Other 42 options include retrofitting or replacing structures, or even using lower voltages (although the 43 latter will, at best, provide a few extra inches). 44 45 46 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 45 1 Methodology D: Simplified Battery Charge Level Simulation 2 To assess the risk of battery depletion on an individual train basis , assess shore power 3 requirements, and determine logistical plans in case of an unexpected ly flat battery, w e worked 4 out a sample operating plan (Figure 25(A)) for a fairly sparse hypothetical commuter service on 5 a 50-mile line, half of which is electrified . Sparse services are logistically most challenging 6 because there are few opportunities for swapping out e quipment when problems arise . 7 8 9 (A) Sample operating plan for sparse service Set C A B C D E A B D A B C E D A C Train # Schd Time Miles DH 5799 700 702 704 706 708 710 712 714 711 716 718 720 715 722 798 Town E/Yard 5:30 6:05 6:35 7:05 7:35 9:00 10:35 12:35 15:05 15:35 16:05 19:05 22:35 Town D 15 10.0 5:45 6:20 6:50 7:20 7:50 9:15 10:50 12:50 15:20 15:50 16:20 19:20 22:50 Town C 13 8.7 5:58 6:33 7:03 7:33 8:03 9:28 11:03 13:03 15:33 16:03 16:33 19:33 23:03 Begin Electrification 10 6.7 6:08 6:43 7:13 7:43 8:13 9:38 11:13 13:13 15:43 16:13 16:43 19:43 23:13 Town B 7 4.7 6:15 6:50 7:20 7:50 8:20 9:45 11:20 13:20 15:50 16:20 16:50 19:50 23:20 Town A 10 6.7 6:25 7:00 7:30 8:00 8:30 9:55 11:30 13:30 16:00 16:30 17:00 20:00 23:30 Downtown 20 13.3 6:45 7:20 7:50 8:20 8:50 10:15 11:50 13:50 16:20 16:50 17:20 20:20 23:50 Layover 5 4:25 6:50 7:25 7:55 8:25 8:55 10:20 11:55 13:55 15:55 16:25 16:55 17:25 17:55 20:25 23:55 Downtown 35 5:00 7:25 8:00 8:30 9:00 9:30 12:30 16:30 17:00 17:30 18:00 18:30 21:00 Town A 20 13.3 5:20 7:45 8:20 8:50 9:20 9:50 12:50 16:50 17:20 17:50 18:20 18:50 21:20 Town B 10 6.7 5:30 7:55 8:30 9:00 9:30 10:00 13:00 17:00 17:30 18:00 18:30 19:00 21:30 End Electrification 7 4.7 5:37 8:02 8:37 9:07 9:37 10:07 13:07 17:07 17:37 18:07 18:37 19:07 21:37 Town C 10 6.7 5:47 8:12 8:47 9:17 9:47 10:17 13:17 17:17 17:47 18:17 18:47 19:17 21:47 Town D 13 8.7 6:00 8:25 9:00 9:30 10:00 10:30 13:30 17:30 18:00 18:30 19:00 19:30 22:00 Town E/Yard 15 10.0 6:15 8:40 9:15 9:45 10:15 10:45 13:45 17:45 18:15 18:45 19:15 19:45 22:15 Next Train # 704 710 712 718 714 720 716 722 702 798 708 706 700 Repeat 6:35 9:00 10:35 15:35 12:35 16:05 15:05 19:05 6:05 22:35 7:35 7:05 5:30 Layover Time 0:20 0:20 1:20 5:50 2:20 5:20 1:20 1:20 11:50 3:50 12:20 11:20 7:15 CDMI/Toilet X X X X X Charging Time 6:24 1:54 1:54 1:54 1:54 1:54 1:54 7:29 1:54 1:54 1:54 5:54 1:54 (B) Battery level forecast for sample operating plan Set C A B C D E A B D A B C E D A C Train # Schd Time Miles DH 5799 700 702 704 706 708 710 712 714 711 716 718 720 715 722 798 Town E/Yard 70% 56% 90% 58% 55% 90% 82% 80% 87% 74% 71% 87% 80% Town D 15 10.0 66% 53% 86% 54% 51% 86% 78% 77% 83% 70% 68% 83% 76% Town C 13 8.7 63% 50% 83% 51% 48% 83% 75% 73% 80% 67% 65% 80% 73% Begin Electrification 10 6.7 61% 47% 81% 49% 46% 81% 72% 71% 78% 65% 62% 78% 71% Town B 7 4.7 63% 50% 84% 52% 49% 84% 75% 74% 81% 68% 65% 81% 73% Town A 10 6.7 68% 54% 88% 56% 53% 88% 80% 78% 85% 72% 69% 85% 78% Downtown 20 13.3 76% 63% 96% 64% 61% 96% 88% 86% 93% 80% 78% 93% 86% Layover 5 100% 78% 65% 98% 66% 63% 98% 90% 89% 100% 95% 82% 80% 100% 95% 88% Downtown 35 100% 93% 79% 100% 81% 78% 100% 100% 100% 97% 94% 100% 100% Town A 20 13.3 100% 100% 88% 100% 89% 86% 100% 100% 100% 100% 100% 100% 100% Town B 10 6.7 100% 100% 92% 100% 93% 90% 100% 100% 100% 100% 100% 100% 100% End Electrification 7 4.7 100% 100% 95% 100% 96% 96% 100% 100% 100% 100% 100% 100% 100% Town C 10 6.7 98% 98% 92% 98% 94% 94% 98% 98% 98% 98% 98% 98% 98% Town D 13 8.7 94% 94% 89% 94% 91% 91% 94% 94% 94% 94% 94% 94% 94% Town E/Yard 15 10.0 91% 91% 86% 91% 87% 87% 91% 91% 91% 91% 91% 91% 91% Next Train # Repeat 90% 90% 82% 74% 80% 71% 87% 87% 56% 80% 55% 58% 70% Layover Time CDMI/Toilet Charging Time Figure 25. Outputs from simplified battery charge level simulation based on sample operating plan for sparse service 10 11 Our battery -level simulations based on energy consumption calculations ( Figure 25(B)) 12 show that the AM peak inbound service has the lowest battery levels due to overnight HEP 13 loads. Nevertheless, a t no point did any trains begin a run with less than 55% charge after laying 14 over for the night, nor enter the electrified zone with less than 49%. This is true even if the 15 outlying yard was not provided with shore power. But if the service does not operate during the 16 weekends, it would be necessary either to deadhead back to the electrified zone, or to provide 17 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 46 shore power at the outer end. Operating a weekend service would have higher operating costs 1 but could lead to infrastructure savings. 2 This sample operating plan also proved out that it was possible to provide extra “charging 3 cycles” in the operating plan in case battery levels becomes unexpectedly depleted for any 4 reason. Sets A, C, and D have extra layover time downtown in the electrified zone in case of an 5 unplanned low-charge condition. Plenty of opportunities exist for set swaps at the outer yard in 6 case a specific set needs to be moved onto a recharge cycle, and set step -ups are possible at the 7 downtown terminal for emergency manipulations. Fleet manipulations to get locomotives with 8 “low batter y warnings” onto daytime charge cycles are not difficult even on lines with relatively 9 sparse service frequency. 10 These are typical concerns an operations manager would have about operating this new 11 type of equipment with energy -based distance constraints that are more restrictive than a diesel. 12 We show that it is possible to work with this through operating plan design. Obviously, plans for 13 each proposed service would need to be worked out individually, through proper consultation 14 between the capital design and operations disciplines . However , we believe additional risks 15 introduced by the range constraint can be mitigated to an acceptable level. 16 17 Methodology E: Infrastructure Efficiency Comparison 18 Implicit in these strategies is a goal of achieving the m aximum carbon -reduction from commuter 19 rail operations whil st minimizing fixed infrastructure investment needs, a theme that was 20 explored in ( 5). This methodology provides a high -level assessment of new infrastructure 21 requirements (route -miles electrified) versus GHG reductions achieved compared to other 22 approaches, such as the diesel dual -mode intermittent electrification proposed in ( 12), and a 23 hypothetical full -electrification scenario . The Philadelphia case studies (Strategies 3 and 4) were 24 not include d because they use existing electrification s. 25 Table 12 shows the results of this analysis. As can be seen, the BEL -enabled approaches 26 are incredibly infrastructure -efficient, although Strategy 6 approaches sacrifices rolling stock 27 utilization to achieve this result in very low traffic density areas. As for GHG performanc e, the 28 BEL -enabled approaches offer far superior reduction to diesel dual -mode based intermittent 29 electrification, whilst providing substantial infrastructure savings over full electrific ation. The 30 performance of the diesel dual -mode strategy proposed elsewhere ( 12) is shown at the end of 31 Table 12 for comparison with the more environmentally effective strategies proposed in this 32 research . 33 34 35 Table 12. Infrastructure efficiency and greenho use gas reduction : comparative assessment. 36 37 Case Study Line (A) (B) (C) (D) (E) % Route Miles Electrified % GHG Reduction Boston North Fitchburg 25.3 0.0 25.3 53.7 28.4 (Strategy 2) Lowell 25.5 0.8 24.7 55.5 30.0 Haverhill 22.8 0.8 22.0 50.4 27.6 Newburyport 18.3 0.8 17.5 36.2 17.9 Rockport 0.0 18.3 0.0 35.3 17.0 Total 89.5 120.9 43% 100% * Chicago North BN (Aurora) 38.4 0.0 38.4 38.4 0.0 and West CNW -W (Elburn) 29.7 0.0 29.7 44.0 14.3 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 47 Case Study Line (A) (B) (C) (D) (E) % Route Miles Electrified % GHG Reduction (Strategy 5) CNW -NW (Harvard) 31.5 0.0 31.5 62.8 31.3 McHenry Spur 0.0 0.0 0.0 65.8 7.6 MD-North (Fox Lake) 32.3 2.9 29.4 49.5 17.2 MD-West (Elgin) 36.6 5.4 31.2 39.8 3.2 NCS (Antioch) 29.9 12.7 17.2 55.7 25.8 Total 177.4 99.4 64% 100% * Chicago North Madison via Rockford 41 41 161 120 and West Regional Janesville via Rondout 32 32 99 67 (Strategy 6) Fond du Lac /Milwaukee 36 32 4 156 120 Total 77 307 20% 100% * Minnesota St. Paul -St. Cloud 23 23 82 59 (Strategy 6) Coon Rapids -Duluth 44 23 21 140 119 Tota l 44 178 20% 100% * Hypothetical Full Electrification Total 100% 100% Diesel Dual -Mode London Paddington to Intermittent Plymouth and Paignton Total , Reference ( 12) 50% 54% 1 Note s: (A) = Electrified route miles; ( B) = Electrified route miles shared with other routes; (C) = Net electrified 2 route mile; (D) = Limits of service ( i.e., m ileage from downtown); (E) = Non -electrified route miles. *All diesel 3 locomotives were eliminated in revenue service , thus achieving a 100% reduction in GHG emissions ; the only non - 4 electric locomotives remaining are emergency back -up locomotives, and those needed for work train service during 5 power outages. 6 7 8 CONCLUSIONS 9 As concern mounts about GHG emissions, commuter railroads should exp lore electrification and 10 battery technology. Although no BEL has been designed for commuter service as of 2022, it 11 should now be possible to develop a BEL specifically for commuter rail where a market exists. 12 This should be an area for further research, prototyping, and proving out, with research and 13 development funding from government climate action/energy research grants. Combined with 14 judicious electrification based on maximizing each substation’s network reach, BELs offer 15 considerable promise for com muter rail both in operating convenience and environmental 16 sustainability. 17 We examined six strategies for electrification of traditional commuter rail systems 18 assuming that BELs suitable for commuter service was developed (based on specifications 19 describe d briefly in this paper). Of these strategies: 20 21  Strategies 1 and 2 are suitable for more compact metropolitan areas where commuter 22 lines radiate from a central station in different directions. Strategy 1 is suitable for cities 23 where the commutershed exte nds out less than 25 miles and does not require the use of 24 BELs. Strategy 2 is suitable for cities with commutersheds up to 50 miles and utilizes 25 BELs. 26  Strategy 3 is for electric commuter rail cities that are looking to extend electric service 27 beyond exis ting electrification infrastructure using BELs. 28 Partial Electrification Strategies for Allen , Lu, Trout Diesel Commuter Rai l’s Climate Challenge and Aurelius 48  Strategy 4 can be used to provide a regional service to connect two or more commuter 1 rail cities each with existing or future electrified commuter rail systems. 2  Strategy 5 is suitable for megaregions whose co mmutersheds extend more than 50 miles 3 from the downtown that do not currently have electrified commuter rail. It may also be 4 suitable for supporting regional services in sparse regions where local desires exist for 5 such service to be electric (rather than operated with alternate fuels). 6  Strategy 6 can be used to provide regional service s beyond the typical commutershed to 7 smaller cities or remote parking facilities that extend up to 120 miles beyond the limits of 8 electrification. Operating more than 120 m iles in non -electrified territory is currently a 9 challenge for BELs because their range is not as long as diesel locomotives . 10 11 Some practical implementation matters remain to be worked out. But this analysis shows 12 that given current technological progres s, a modern electrified network operated with a mixture 13 of straight electrics (locomotives and/or multiple -unit cars) and BELs should be cheaper than a 14 conventional electric solution and would have a wider geographic reach. Thus, service sponsors 15 should s tart to examine expanding electric service now, whether by new -start electrification, 16 BEL extensions of existing electrified systems, or new regional or interregional travel 17 opportunities. 18 19 20 ACKNOWLEDGEMENTS 21 The authors thank J.E. Kesich, Jim Heimbuecher, Walter Simpson, Lew Hoens, Adam Otsuka , 22 Bob Newhouser, David Mangold , and M.J. Shiffer for useful discussions . The authors are also 23 grateful to the anonymous reviewers at both the Transportation Research Board and the 24 American Society of Mechanical Engine ers’ Joint Rail Conference who provided useful 25 feedback on all previous draft manuscripts from this project. The views are those of the authors 26 and do not necessarily reflect the official policy of any railroads, manufacturers, government 27 bodies, or other organizations. Any errors are the sole responsibility of the authors . 28 29 30