How'd I miss that? I should stop skimming;)

...............

^^ Extend the brown line to Jefferson Park!

what a pleasant surprise to ride the new rail cars on the blue line on the way home from work today! I can't believe smooth they are, and they're not even running off AC yet...

They are --- or rather, they use AC motors in the propulsion system, but the third rail is still 600VDC and probably will remain so. The railcars have transformers to convert the power supply.

From an energy standpoint, does AC third rail power supply offer more cost savings for electricity over direct current power supply? I know about the acceleration advantages, noise and smoother operation, just wondering about the actual pull of electricity into the traction motors.

stop building roads in sprawl move closer to where you work; encourage employment density and concomitant household density



I have no pity on suburbanites who bitch about their crazy commutes....they bough the myth hook line sinker

stop building roads in sprawl move closer to where you work; encourage employment density and concomitant household density



I have no pity on suburbanites who bitch about their crazy commutes....they bough the myth hook line sinker


Build transit; build / reuse developments that can effectively utilize transit; increase transit services in dense areas instead of cutting services and building more choked roads

"Move closer to where you work" sounds so easy. But grown-ups often own their houses, have spouses who work, or have kids they want to benefit from specific school districts. Do you expect them to move every time one spouse or the other changes jobs?

While I'm not an electrical engineer, I'll attempt a layman's explanation as I understand it. Generally, AC power running at high voltages (e.g. up to 25kV) on overhead wires is less susceptible to current loss over long distances than the lower voltage (generally 500-900V) DC power used for third rails (very high voltages are more prone to arcing and thus are avoided on third rails). The current loss on third rail systems is mitigated by having more closely spaced power substations than would otherwise accompany a high voltage AC system -- substations are, of course, very expensive.

In terms of how this all nets out for energy efficiency and cost efficiency, I think the answer is "it depends." DC is more prone to current loss than AC, third rail is generally cheaper to install/maintain than an overhead catenary, but DC systems will require a greater number of expensive substations. So, the most efficient solution depends on all of those.

In general, global precedent and experience certainly implies that for short, "metro" rapid transit routes, third rail DC is more cost effective, while for longer commuter rail or intercity routes, overhead AC is preferred.

Theoretically there would be substantially less loss between substations. AC can be transmitted long distances with much less loss.

I'm told that power consumption is now a limiting factor on some CTA lines, which prevents more trains from being run during rush periods. But that's not why AC was specified for this order. Instead, Kruesi was at a transit conference in Paris and was embarrassed when someone said "you guys in Chicago are still buying DC cars?"

I could have sworn I read or heard somewhere that these cars can run off either AC or DC, and eventually they'll get rid of all DC-only cars so they can turn the system to an AC system, which would definitely be a more efficient system in general.

But compared to the old cars, I felt like I was in the future riding those new cars :tup:

^Definitely no DC motors on these cars. You may be thinking of the regenerative braking system, which I think is switched off at the moment but I'm not 100% sure. I'm also not sure what the expected energy savings from regenerative braking are for these particular railcars. Of course, power draw is both a systematic issue and driven by peak demand, and thus there would not be appreciable savings until a substantial portion of the fleet have the technology and the magnitude of savings (both relative and absolute) will vary somewhat with the service level. The general range for net power savings seems to be in the 5-15% range, if the entire fleet is converted.

While you raise a good point regarding short-term mobility vis-a-vis home and work locations, the article does say she's being doing this for 20 years; i.e. basically since I-355 first opened, and thus presumably with the assumption of an imminent extension further northward. After 20 years, it's pretty hard to be sympathetic towards her plight on either the schooling or underwater-mortgage grounds.

In support of your general point, I know a good number of people who, 5 years ago, swore they'd never work in the suburbs, or buy a car anytime soon (maybe after the family/kids got started), but ended up doing both sometime since 2008, commuting from the city to jobs in the I-90 or I-88 corridors. They really didn't want to do the commute; they also really didn't want to move from their urban neighborhoods. Importantly, they also needed jobs.

The difference of course is that most of them would rather their jobs just relocate downtown, rather than following Sugar Grove Mama and complain to a newspaper about how another expressway should be built.

From what I know of electrical properties, both DC and AC can be transmitted over great distances with relatively little loss. In the case of a system where there is a single, well-defined use of the power the other factors involved in electrical transmission and use would play a much larger role in power loss than simple AC vs DC.

I'm gonna get a little bit wonkish here, but...

In defense of Sugar Grove Mama, the lack of a complete second orbital highway is really a drag on mobility through the region, placing heavy traffic on the Tri-State and the routes through the city. The 53 extension and the Illiana are two of the three missing segments in that orbital highway, so I support those plans - especially because they would be paid for with toll revenue and not the state's money. The federal contribution would come from the highway "pot" of funds, which is distinct from the transit "pot".

What all that means is that highway construction would NOT be done at the expense of transit. People tend to think that one competes with the other for money, but that just isn't the case here in Chicagoland. The state is broke, of course, so it's not like there's any money to be had from the general fund anyway.

I'd also love to see something like LA's Measure R, or Denver's FasTracks... we don't have ballot initiatives like California does, but we could do an "advisory referendum" (essentially just a massive, government-led poll) on a Chicagoland-only tax increase for transit expansion. If that Tribune poll a few weeks ago was correct, then the referendum should get significant support. Publish a list of visionary, well-planned transit projects with a definite pricetag and send it to the voters.

I would include about $12-15 billion worth of transit projects. There are some ideas that have real potential, but the people in charge are pushing total loser ideas, like the STAR Line or the SouthEast Service. The Inner Circumferential Rail, for example..

Virgin America skips O'Hare
 

I just read that Virgin America will skip ORD again and make its appearance at DFW. The reason again is gate space, this is exactly why the Western Terminal needs to get built. The city needs to control the gates, not AA or UA.

While some will argue this is not a big loss, it is more passengers that will not be using ORD and less revenue for the city. What the hell is wrong with Aviation commission. In my opinion ORD is one of the, if not the most important asset for Chicago. Yet in last 10 years passenger traffic has fallen by 21% and flights by 12.5%. Yeah some of it is the recession, but darn it the city needs to step up and do something.:hell:

^How would having a gate devoted to two Virgin America flights a day increase passenger numbers more than having eight UA or AA departures from the same gate?

Thanks for the trenchant tidbit....I'll keep it mind when I grow up.

Adults also are capable of evaluating options; choosing between options; and realizing that said choice among said options have consequences.

I know america...consequences.....novel concept

Having additional gates allows the airport flexibility to add carriers. Take VA for example, the airline has been looking at mid-continent airport which they would eventually to collect passengers from other midwestern and mid-continent cities. This brings in additional passengers.

UA and AA hubs are a good thing, but it also leaves the city very little flexiblity in doing things at the airport without the airlines buy in. ORD will need gate capacity, to compete with the likes of ATL, DIA and other airports.

Chicago should be angling to make ORD the Star Alliance or One World hub for North America. As such, untangling the runways and building 1st rate facilities with sufficient gate capacity should be the priority of OMP.