I'm a bit surprised that Metra has not considered ALP45DP's for connecting the electric line with the rest of the system without having to switch trains.
I suspect you are talking Chicago? The 'Electric' line is the old IC/CSS&SB line. This is a commuter line, the passengers get off in Chicago to go to work - What would a through connection gain here? They do not even use the same station...
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin
Illinois Central and South Shore have been operating EMU's in suburban service since the wires went up in 1908 (South Shore) and 1926 (IC). Neither operation shares any trackage or stations with the rest of the suburban network so dual-power locomotives would be a complete waste of money.
Incidentally, South Shore suburban service is operated by NICTD and is not part of Metra. Hegewisch is the only station stop in Chicago not served by Metra.
DutchrailnutCatenary near Chicago is DC powered something the DP can not handle.
In my opinion, it would not be difficult to run AC synthesized drive from a sufficiently high-voltage DC source -- if some obvious safeguards are provided. We had a thread recently regarding the DC link voltage to various OTS inverters. You might in fact bypass some of the complicated and costly stuff in a dual-mode locomotive when you do not need a HV transformer that can step down from typical AC cat voltage, or a rectifier for the cat AC that produces 'good enough' DC for the traction inverter(s).
I will let others comment on the practicability of DC-to-DC conversion at the required peak currents if the Chicago catenary voltage doesn't match the chosen DC link voltage closely enough at all times.
This is not, of course, to advocate the purchase or use of dual-mode locomotives on Chicago electric lines. I agree with other posters that such a thing is not warranted by the operating circumstances (or in my opinion any likely expansion of electrified service either with AC or DC.)
All rservice on METRA-Electric and the South Shore is handled by 1500V DC MU cars. These cars give better service and higher performance than any locomotive-hauled or pushed commuter service anywhere else in the Chicago area and better service than locomotive hauled or pushed commuter service anyhwere else, in terms of faster acceleration and smoother and quicker stops. The are of course equalled by the new M-7's and M-8's of Metro-North and LIRR.
Being used to such good service, these commuters would be unhappy with the service that would be provided by any locomotive hauled or pushed train, with its slower acceleration.
I someday Elkhart were to be part of the Chicago commuter area, pretty farfetched, you might have a point. And for the line going south, extending the catenary a few mies would be cheaper than those very expensive dual-service locomotives.
The IC and Rock Island lines both serve Blue Island at adjacent stations. Metra constructed a connection between lines for equipment moves and has used diesel power on the electric line, but there is no interline service. It's feasible to run trains from the Rock Island to the electric, but it's probably pointless.
Espeically since Milleneum Station, Randolf Street, is very close to capacity. So is the three-track section of RofW at Van Buren Street.
The Blue Island Branch has always been a relatively low-traffic operation and has not had any Sunday service for several years now. It is a single-track branch with a passing track at Halsted so the branch itself has capacity constraints.
Metra has universal ticketing (multi-ride and monthly tickets are not restricted to one line) so there have been some walking transfers at Blue Island between the Rock Island and the Illinois Central.
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