HomeDiagramsDatabaseMapsForumSkyscraper Posters

Go Back   SkyscraperPage Forum > Discussion Forums > Transportation


Thread Tools Display Modes
Old Posted Jul 25, 2018, 11:28 PM
ardecila's Avatar
ardecila ardecila is offline
Join Date: Jun 2006
Location: the city o'wind
Posts: 13,210
Originally Posted by bnk View Post
Isn’t Metra diesel electric pretty much electric already ?

The Diesel drives the electric motors that run those trains I didn’t notice a major acceleration problem compared to other systems.


It seems to me that the diesel electric locomotive us are basically a portable electric power station
Yes, American diesel locomotives commonly use a diesel-electric transmission, but the "diesel" part of that equation imposes significant penalties on the overall weight of the train, the output of the generator, and thus the amount of torque the electric motor can produce.

Train performance is described by power to weight ratio and adhesion factor. The power-to-weight ratio of an EMU is roughly three times that of a diesel locomotive and passenger cars - it weighs hundreds of tons less, no need to haul heavy diesel fuel and generator, plus modern EMU designs are just generally lighter, using crumple zones like an auto instead of tons and tons of steel to make a perfectly rigid carbody. (These modern designs are technically illegal in the US because of our outdated ideas on train safety, but FRA often issues waivers to use modern designs under certain circumstances).

The adhesion factor is the other piece, and it is also much higher for an EMU, since there are many drive wheels spread throughout the train instead of just a handful up front. The adhesion factor explains why an EMU has significantly better performance than just an electric locomotive hauling unpowered coaches.

So why use locomotives at all? The advantages of EMUs are most profound when the train is either stopping frequently, or traveling at very high speed. So either for urban rail operations with closely-spaced stops, or high-speed rail above 150mph. For regional and intercity services with stops miles or tens of miles apart, where very high-speed travel isn't warranted, the locomotive-and-coaches model still makes a lot of sense. It's very easy to take apart and re-assemble trains and cheaper to maintain them. Some Metra lines with wide stop spacing (Heritage Corridor, Rock Island, NCS) probably don't warrant the extra expense of multiple-unit trains. I'm honestly not sure why South Shore continues to operate EMUs rather than just install better vent systems at Millennium Park.
la forme d'une ville change plus vite, hélas! que le coeur d'un mortel...

Last edited by ardecila; Jul 25, 2018 at 11:44 PM.
Reply With Quote
Old Posted Jul 25, 2018, 11:28 PM
Busy Bee's Avatar
Busy Bee Busy Bee is online now
Leftist Correctist
Join Date: Feb 2006
Location: Spaceship Earth
Posts: 5,160
Haha, a diesel generator is no substitution for the instantaneous juice you get from a 25kV overhead line. It's like the difference between a Dustbuster and a Shop-Vac.
You slip me the cash and I'll slip you the wiener. <><><><><><>IMPEACHMENT NOW!

For me it can be reduced to this: For every personal freedom we gained from the automobile, we lost in social cohesion.

Last edited by Busy Bee; Jul 26, 2018 at 3:59 PM.
Reply With Quote
Old Posted Aug 3, 2018, 6:53 PM
M II A II R II K's Avatar
M II A II R II K M II A II R II K is online now
Registered User
Join Date: Aug 2002
Location: Toronto
Posts: 44,591
Water taxi service may expand for new riverfront developments



- Planned development along the river has led to talks between Chicago Water Taxi, part of Wendella Sightseeing, and builders about adding new stops north and south of downtown, starting in the next two to three years. --- “We think it’s a no-brainer to add a couple more and make it an amenity for the thousands of residents and employees we’re going to have at Goose Island,” said Zack Cupkovic, director of special projects for R2 Cos., which owns about 10 percent of Goose Island as well as the Morton Salt property. The developer plans office space, bars and restaurants and entertainment for the sites.


Reply With Quote
Old Posted Aug 9, 2018, 2:11 PM
jpIllInoIs's Avatar
jpIllInoIs jpIllInoIs is offline
Registered User
Join Date: Dec 2005
Posts: 902
The Midwest High Speed Rail Association is asking for a letter writing (email&twitter) campaign support for the Cross Rail initiative. Link Here
You can read all about Cross Rail HERE
I believe in the CrossRail because it makes higher use of the MED/IC line and connects that line to CUS and west Loop and provides a one seat ride to Ohare for Southsiders and Hyde Parkers. Crossrail also envisions a stop at the "78" development and at Ashland Ave in Fulton Market. Providing links to our hottest sub market and to our next mega project.
Its an ambitous plan but one that modernizes existing assets Like the 2 bypass tracks that exist in CUS and the MDW rail row to Ohare.
There are grander plans envisioned like a tunnel tracks part of the West Loop Gateway station which would include the Clinton St Subway adn a tunnel track into the OHare terminals and possibly beyond. As in all major projects it will be incremental.
Anyway the link above is the least I or anyone can do to show support....
Reply With Quote
Old Posted Aug 9, 2018, 8:56 PM
the urban politician the urban politician is online now
The City
Join Date: Jul 2004
Location: Libertyville, IL
Posts: 14,914
Victim rights > Criminal rights
Reply With Quote

Go Back   SkyscraperPage Forum > Discussion Forums > Transportation
Forum Jump

Thread Tools
Display Modes

Forum Jump

All times are GMT. The time now is 8:06 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.