EMUs VS Engine on Electrified Track?

[tomj]

So let me explain, cause this is going to be a bit of a long one. I am writing a piece and I am evaluating the cost of rail travel and am trying to determine how much rail equipment would cost.

So the question is, does an EMU have a significantly lower operating cost over a train hauled by an electric powered engine? Based on the CalTrain Order, a Stadler KISS costs around ~$34.5 million per train vs ~$21.7 million for a 6 car train hauled by a Euro Sprinter. I can't find an approximate number of how much an EMU would cost to run. I know an EMU is far better compared to a diesel hauled train, hell even a DMU is better. Based on the rough estimate I came up with shows that an EMU costs 37% more than a similar locomotive hauled train. Is the cost to run an EMU over its life cycle at least 37% lower to justify the cost. Also for the sake of what I am writing, the electrification is assumed to be happening, I am asking about choosing between EMU or Electric locomotives.

[DutchRailnut]

reason they go with EMU is that they are way faster in and out of station than a locomotive hauled train.
an EMU also gives you way more redundancy in power.

[tomj]

Unfortunately I am writing a paper that will get picked apart on the basis of cost/benefit analysis and I can't really quantify the speed into a dollar amount. I'm going down the energy efficiency/maintenance costs/ wear and tear on the tracks of the two.

[electricron]

Two great web sites with great information - both pro and con.

Pro = https://www.eesi.org/articles/view/elec ... istic-goal" onclick="window.open(this.href);return false;

Con = http://energyskeptic.com/2016/electrifi ... ight-rail/" onclick="window.open(this.href);return false;

p.s. I would like to point out that the first link referenced the second link.

Both links point out why US railroads chose diesel electric over just electric locomotives when they phased out steam locomotives. America's railroads are privately owned, and the costs to switch over to electric is too large to finance privately. In the rest of the world, the railroads are owned by governments - they just raise taxes to fund the huge costs to switch.

I'm afraid the only places you'll see many electric locomotives powering trains in the USA will be limited to those rail corridors owned by government agencies - or future privately owned High Speed Rail corridors. The privately owned freight railroads will oppose switching to electric locomotives forever.

[talltim]

The main advantages of an EMU over an electric loco+coaches are:
-EMUs can have more axles powered so can get the power down better, giving better acceleration. As well as providing a faster service for passengers, this also translates into allowing a higher frequency service witht he same infrastructure.
-All vehicles can carry passengers ,this becomes more important when your trains are reaching the length of the platforms. Trains longer than platforms can be coped with at through stations by the use of selective door opening (SDO), but at terminals a train that is too long could overhang switches and prevent use of other platforms.
-EMUs tend to cause less track wear. Even if the total weight of the train is the same, locos are heavier and cause more wear. It tends to be that as the train gets longer the balance shifts more in favour of loco hauled. I seem to remember reading that below 6 cars, EMU has the advantage, longer than that the lighter weight of the extra unpowered coaches of loco hauled claw it back. I don't know how the US freight railroads calculate the cost of track access, in the UK each vehicle type has a track access cost (paid by the operator to the infrastructure provider), calculated on a formula based on axle weight/suspension type/speed and so that element of running costs of different types can be easily compared. The current 'price list' for Network Rail in the UK is here https://cdn.networkrail.co.uk/wp-conten ... e-List.xls" onclick="window.open(this.href);return false; (Note that you would have work out what the vehicles are, EMU class numbers start with 3 or 4 (rows 67-145)(M for a motored vehicle, T for a trailer). Electric locos are 90 and 91 (rows 159-160). There seems to be only one price for a coach (row 178) although there are very few coaches still in use in the UK (and no loco hauled commuter coaches). Even if track access costs are not directly charged (the operator owns the infrastructure), the reletive costs still apply. I might do an access charge comparison for loco hauled vs EMU using these figures if I get time.

A cost disadvantage of EMUs is the extra cabs. Cab equipment costs money. A loco in push pull with a driving trailer will have two or three cabs for any length of train (depending whether the loco is single or double ended) Coupling two EMUs means 4 cabs, three means 6. Also, at a rough guestimate, 6 cabs is about the same amount of non passenger space as a loco. Optimising your EMU length can help reduce this problem, shorter units allow more flexibily in train length, but cost more in cabs and unused space, longer units mean that you will be carrying more fresh air around at non-peak times. As an example, the Thameslink service through London (UK) replaced all the previous 4 car EMUs (used in multiple) with a mix of 55 12 car and 60 8 car units. These units never couple (in normal service). The line is busy enough that the cost of using 12 car units at part capacity at non-peak times is cancelled out by the extra space provided by no having 4 unused cabs for peak times.

[tomj]

Thank you. What I am writing is making the assumption that an 8 car Stadler KISS or Siemens Desiro double deck. I am writing this for California and our stations were built for low floor double deck rail cars. From the numbers I have seen, a 6 car KISS can fit about the same number of people as a 6 California Car train, with 2 added cars for Business class which the state has been wanting to add for years. Also the trains don't get rearranged during the day, so having shorter trains that can be rearranged doesn't seem to be a big issue.

[electricron]

Thank you. What I am writing is making the assumption that an 8 car Stadler KISS or Siemens Desiro double deck. I am writing this for California and our stations were built for low floor double deck rail cars. From the numbers I have seen, a 6 car KISS can fit about the same number of people as a 6 California Car train, with 2 added cars for Business class which the state has been wanting to add for years. Also the trains don't get rearranged during the day, so having shorter trains that can be rearranged doesn't seem to be a big issue.

Stadler KISS trains are basically double deck versions of their FLIRT trains, when it comes down to their EMU propulsion machinery. FLIRT trains can also have diesel electric power cars added, check out TexRail DMUs, and can also have batteries added using a power car, check out the new Arrow commuter rail service in San Bernardino. The basic difference between a FLIRT EMU, DMU, and Battery EMU FLIRTs is where the electricity comes from ; from the power grid, from a diesel generator on the train, or from a battery which can be charged with electricity from the grid or from the train. The motors used to propel the trains are basically identical. The second link I provided earlier explains that very well.

Most of various different Stadler train efficiency gains over tradional push pull locomotive powered trains arises from their lighter weight, nor from where the electricity comes from. Is it more expensive to purchase diesel motors on the trains or construct a power distribution system over the tracks determines which is cheaper to do.

America’s freight railroads have decided using diesels is cheaper than a power distribution. Europeans and other nations in the world decided upon power distribution over the tracks is cheaper. I just wanted to point out that in most European countries, the electric utility is also owned by the government along with the railroad corridors. In America, most electric utilities are private enterprise just like most of our railroad corridors. Who owns what has a huge impact on which way is cheaper; EMUs vs DMUs, vs diesel electric locomotives.

[mtuandrew]

A way to quantify speed and acceleration could be in schedule time, turnaround time (cleaning, draining toilets, restock), and runs per crew. Might also be able to assume a marginally higher fare for faster service. That said, acceleration won’t be that much of an issue unless you have stops every five miles or less - it’s not uncommon for locomotives to accelerate faster at speeds above 30 mph than MUs do.

[NorthPennLimited]

I seem to recall SEPTA paid around $1.5 million per car for the Silverliner V procurement. Hyundai undercut all the competing bids to get a toe-hold in the US railroad market.

The Silverliner is EMU.

[talltim]

Thank you. What I am writing is making the assumption that an 8 car Stadler KISS or Siemens Desiro double deck. I am writing this for California and our stations were built for low floor double deck rail cars. From the numbers I have seen, a 6 car KISS can fit about the same number of people as a 6 California Car train, with 2 added cars for Business class which the state has been wanting to add for years. Also the trains don't get rearranged during the day, so having shorter trains that can be rearranged doesn't seem to be a big issue.

Stadler KISS trains are basically double deck versions of their FLIRT trains, when it comes down to their EMU propulsion machinery. FLIRT trains can also have diesel electric power cars added, check out TexRail DMUs, and can also have batteries added using a power car, check out the new Arrow commuter rail service in San Bernardino. The basic difference between a FLIRT EMU, DMU, and Battery EMU FLIRTs is where the electricity comes from ; from the power grid, from a diesel generator on the train, or from a battery which can be charged with electricity from the grid or from the train. The motors used to propel the trains are basically identical. The second link I provided earlier explains that very well.

Most of various different Stadler train efficiency gains over tradional push pull locomotive powered trains arises from their lighter weight, nor from where the electricity comes from. Is it more expensive to purchase diesel motors on the trains or construct a power distribution system over the tracks determines which is cheaper to do.

America’s freight railroads have decided using diesels is cheaper than a power distribution. Europeans and other nations in the world decided upon power distribution over the tracks is cheaper. I just wanted to point out that in most European countries, the electric utility is also owned by the government along with the railroad corridors. In America, most electric utilities are private enterprise just like most of our railroad corridors. Who owns what has a huge impact on which way is cheaper; EMUs vs DMUs, vs diesel electric locomotives.

Think you have missed the point. In this case diesel isn't in the equasion, he is purely comparing electric loco hauled with electric multiple unit.

[John_Perkowski]

In any electric cost analysis, if the railroad is not yet electrified, you have to factor in
- cost of infrastructure on the railroad for electric...catenary and poles
- cost of infrastructure to supply electricity...generating stations for new load, transmission services, and substations along the route.

[mtuandrew]

The OP is specifically comparing electric equipment. Unless one of you can prove that either a DMU or a diesel locomotive is more efficient than an electric, let’s stay with that topic and not “diesel vs electric.”

It is important to ask whether a power distribution network is sufficient for the peak amperage draw a locomotive placed on it, versus the lower peak draw of an EMU set, and by how much that system needs to be upgraded to support locomotives. It’s a problem on SEPTA which they solved by derating their new ACS-64 fleet, as well as modest updates to their Reading-side network.

Also worth noting that for lower-voltage systems (750-1500VDC) an EMU set is considerably more efficient than a third-rail-powered locomotive, simply because there’s a limit to the amount of current that can be drawn through a third-rail shoe or single pantograph. A locomotive can’t draw enough to fully feed its motors. That problem goes away when working with high-voltage systems because of their lower amperage requirements.

[electricron]

The OP is specifically comparing electric equipment. Unless one of you can prove that either a DMU or a diesel locomotive is more efficient than an electric, let’s stay with that topic and not “diesel vs electric.”

It is important to ask whether a power distribution network is sufficient for the peak amperage draw a locomotive placed on it, versus the lower peak draw of an EMU set, and by how much that system needs to be upgraded to support locomotives. It’s a problem on SEPTA which they solved by derating their new ACS-64 fleet, as well as modest updates to their Reading-side network.

Also worth noting that for lower-voltage systems (750-1500VDC) an EMU set is considerably more efficient than a third-rail-powered locomotive, simply because there’s a limit to the amount of current that can be drawn through a third-rail shoe or single pantograph. A locomotive can’t draw enough to fully feed its motors. That problem goes away when working with high-voltage systems because of their lower amperage requirements.

I included DMU FLIRTs with my answer to point out the electric motors propelling the trains were exactly the same as EMU versions of FLIRTs, and also KISS double decker EMUs. Let me repeat that once more, the exact same motors!

Whether or not EMUs with smaller motors are better than locomotives with larger motors depends upon how much horsepower one needs to run the trains the way they desire. Keeping the comparison to what Caltrain is ordering; KISS trains vs the only alternate electric locomotive being built in the USA, a Siemens Sprinter.

Amtrak Siemens Sprinters propulsion system delivers
6,400 kW (8,600 hp) Maximum (Short-Time)
5,000 kW (6,700 hp) Continuous
A locomotive being used in a push-pull consist would have just four powered axles on two bogies.
Some math = 5,000 KW / 2 powered bogies = 2,500 KW/bogie

Caltrain's Stadler KISS propulsion system delivers
6,000 kW (8,000 hp) Maximum (Short-Time)
4,000 kW (5,400 hp) Continuous
KISS power cars also have four powered axels on two bogies, but each consist has two power cars, and therefore each consist can have up to eight powered axels, or 4 powered boogies.
Each Stadler FLIRT or KISS powered boogie can provide 1,000 KW.

So the power required for either train type, a single electric locomotive vs EMU, is within 20% (5,000 KW vs 4,000 KW). Power per bogie are different by 250% (2,500 KW vs 1,000 KW).

Caltrain will be running 6 car EMUs, vs 6 coaches and 1 locomotive - which allows using a locomotive length shorter platform. They could be saving up to 20% on power consumption with less power demand. They should have less wheel slippage with significantly lower power per axle because more axles are propelling the train. Less wheel slippage should also mean faster acceleration and deceleration - and quicker trips.

But with twice as many power bogies to maintain, maintenance costs should be higher. How much higher? That depends upon the reliability of the bogies, availability of spare parts, etc. Golly, the smaller motors might be cheaper. I have no clue where any of us can find that information to make a fair and honest judgement. Does anyone have real maintenance costs per mile for either train? I ask because that data is important judging which train over time will be cheaper for Caltrain to use.

[east point]

New Jersey Transit operations may give you some ideas. This is not always true but : NJT local trains are usually EMUs between short distance local trains. The NJT trains that are express from Newark and Trenton are electric loco hauled as those trains can maintain top speed. Do not know present practices but at one time Amtrak wanted the NJT expresses to maintain 125 MPH. NJT's EMU for whatever reason are still limited to 100 MPH. There have been tests for both types for 125 but if or why it has not been certified ?

[mtuandrew]

East Point: I thought the Arrows were now limited to 80 after “improvements” in a rebuild?

It’s true though, in America ever since the Metroliner the highest speed trains have been motor-hauled rather than EMU. That doesn’t necessarily mean EMUs aren’t suited to >125 mph, they aren’t uncommon overseas for HSR and should have faster acceleration than a locomotive to 125 and above, just that American roads have followed Amtrak’s lead and opted for maintenance simplicity.