 |
Re: BART on Geary?
Author: OldPoleBurner
Date: 01-02-2014 - 14:45
> I really don't know where you get some of your ideas Mr. Mouse.....
> BART is the best thing that ever happened to the Bay Area hands down.....
> I prefer not to imagine living here without it. PERIOD!
Thankyou Scott.
BART, despite all the false starts and bad technology decisions (westinghouse propulsion and train controls), and its odd non-conformist ways; has been a godsend to the Bay Area. Which is why the Bay Area suffers so much when BART burps.
SMART will be the same for Marin, if they actually manage to extend it to where the largest number of people are actually going - Downtown San Francisco (at much less daily cost than the same number of people carried by bus); which I think is technically feasible. When BART was banned off the GGB, it was as much a political decision as it was technical. Yep! there were Marin mouses around then too - constantly nay-saying to the bridge board!
The bridge deck averages 220 ft above sea level, which can be attained from sea level by a 3% incline of only 7300ft, or 4 miles at 1%. Indeed, NOT a big deal at all.
But ever since the bridge decking was replaced several years ago, significantly lightening the load, the weight issue has become almost mute from an engineering perspective. I say almost mute, because of the still tight design margins that must be accounted for. However, with a little "Out of the box" thinking, it is quite doable.
Out of the box thinking such as placing only a single track on the bridge, restricting maximum speed and limiting train length; will cut by more than half, the loading that must be accounted for. The operational impacts of such limitations are also quite tolerable.
At 2 miles per minute (30mph), the entire single track section on the span can be traversed in approx. 4 minutes; after which another train can then enter the span, from either direction. 10 minute peak scheduled head ways in each direction are then workable. With limited train lengths allowing about 500 passengers each; that's still 3,000 people per hour in each direction. Moreover if, as seems likely, schedules predominate in one direction during the commute, as many as 5,000 per hour could be accommodated in that direction (equivalent to 4 lanes of freeway - doubling the bridges people capacity)
Marin mice not withstanding - It is a no brainer!
As to BART on Geary St; that is not too far from the original BART plan, which was four tracks on Market from the bayside, to the Van Ness area, where two of the tracks would turn south onto Mission St, and the other two tracks continuing under Market St and below the Twin Peaks tunnel, to the Sunset District area; and then turning north (near 19th Ave if memory serves) to the bridge.
But after the withdrawal of Marin County (and its bonding capacity), budget cuts had to be made, so that entire line was the victim. However, some of the bond money from San Francisco County was already committed to that line - so it instead went to upgrading the Muni lines on the same route. The two upper bores under Market Street were thus transferred to Muni.
Interestingly, that transfer came with a proviso that BART could reclaim the two bores with five years notice, an option which I think has long since lapsed. In some respects, this was a bad decision; because without 4 tracks under Market St, the promised 90 seconds between Transbay trains, can never be realized in practicality. In fact, because the tube itself was without station stops, it was easily designed to handle as many as 55 trains per hour, but the whole line is now limited to less than 30 per hour, instead of the 46 per hour that multiple tracks (4 mains) in the stations would have afforded. That was a very serious loss - indeed a pennywise and pound foolish decision. The same goes for the elimination of the four tracks originally planned through Oakland - that occurred in the same decision.
As to the gauge of eBART; at last I had any contact with BART's "Project Manager" for eBART, (in 2010) it was to be standard gauge.
After BART had scrapped the idea of sharing r.o.w. for eBART with the UP on the Moccoco line, we had recommended that this gauge change be scrapped in favor of DMUs of BART's existing gauge. That way, no "out of face" rebuild would be necessary to later convert to BART compatible electric operations. But the at the time BART GM refused to consider this. BTW, sharing r.o.w. with UP got dumped solely because of extremely unreasonable demands by UP - In fact, As I reported on Altamont way back then, the demands were bizarre and patently insulting!
As to gauge questions: There are many viable gauges extant in the world, and none costs significantly different than the others. Only where diminutive vehicles and a smaller r.o.w. are used, is there any cost benefits to a smaller gauge. Nor is there any significant cost increase for broader gauges, unless the vehicle width is also increased. BTW, that is not the case with BART, as its cars are actually only 10ft 6in wide at their widest point (pretty standard actually). It is the tubular shape, widest at seat level, that makes them seem so comfortable.
OPB
PS: ---- As to certain Marinites pretending to be railfans, or as anyone actually interested in railways of any sort - does anybody have a mousetrap that actually works!
> BART is the best thing that ever happened to the Bay Area hands down.....
> I prefer not to imagine living here without it. PERIOD!
Thankyou Scott.
BART, despite all the false starts and bad technology decisions (westinghouse propulsion and train controls), and its odd non-conformist ways; has been a godsend to the Bay Area. Which is why the Bay Area suffers so much when BART burps.
SMART will be the same for Marin, if they actually manage to extend it to where the largest number of people are actually going - Downtown San Francisco (at much less daily cost than the same number of people carried by bus); which I think is technically feasible. When BART was banned off the GGB, it was as much a political decision as it was technical. Yep! there were Marin mouses around then too - constantly nay-saying to the bridge board!
The bridge deck averages 220 ft above sea level, which can be attained from sea level by a 3% incline of only 7300ft, or 4 miles at 1%. Indeed, NOT a big deal at all.
But ever since the bridge decking was replaced several years ago, significantly lightening the load, the weight issue has become almost mute from an engineering perspective. I say almost mute, because of the still tight design margins that must be accounted for. However, with a little "Out of the box" thinking, it is quite doable.
Out of the box thinking such as placing only a single track on the bridge, restricting maximum speed and limiting train length; will cut by more than half, the loading that must be accounted for. The operational impacts of such limitations are also quite tolerable.
At 2 miles per minute (30mph), the entire single track section on the span can be traversed in approx. 4 minutes; after which another train can then enter the span, from either direction. 10 minute peak scheduled head ways in each direction are then workable. With limited train lengths allowing about 500 passengers each; that's still 3,000 people per hour in each direction. Moreover if, as seems likely, schedules predominate in one direction during the commute, as many as 5,000 per hour could be accommodated in that direction (equivalent to 4 lanes of freeway - doubling the bridges people capacity)
Marin mice not withstanding - It is a no brainer!
As to BART on Geary St; that is not too far from the original BART plan, which was four tracks on Market from the bayside, to the Van Ness area, where two of the tracks would turn south onto Mission St, and the other two tracks continuing under Market St and below the Twin Peaks tunnel, to the Sunset District area; and then turning north (near 19th Ave if memory serves) to the bridge.
But after the withdrawal of Marin County (and its bonding capacity), budget cuts had to be made, so that entire line was the victim. However, some of the bond money from San Francisco County was already committed to that line - so it instead went to upgrading the Muni lines on the same route. The two upper bores under Market Street were thus transferred to Muni.
Interestingly, that transfer came with a proviso that BART could reclaim the two bores with five years notice, an option which I think has long since lapsed. In some respects, this was a bad decision; because without 4 tracks under Market St, the promised 90 seconds between Transbay trains, can never be realized in practicality. In fact, because the tube itself was without station stops, it was easily designed to handle as many as 55 trains per hour, but the whole line is now limited to less than 30 per hour, instead of the 46 per hour that multiple tracks (4 mains) in the stations would have afforded. That was a very serious loss - indeed a pennywise and pound foolish decision. The same goes for the elimination of the four tracks originally planned through Oakland - that occurred in the same decision.
As to the gauge of eBART; at last I had any contact with BART's "Project Manager" for eBART, (in 2010) it was to be standard gauge.
After BART had scrapped the idea of sharing r.o.w. for eBART with the UP on the Moccoco line, we had recommended that this gauge change be scrapped in favor of DMUs of BART's existing gauge. That way, no "out of face" rebuild would be necessary to later convert to BART compatible electric operations. But the at the time BART GM refused to consider this. BTW, sharing r.o.w. with UP got dumped solely because of extremely unreasonable demands by UP - In fact, As I reported on Altamont way back then, the demands were bizarre and patently insulting!
As to gauge questions: There are many viable gauges extant in the world, and none costs significantly different than the others. Only where diminutive vehicles and a smaller r.o.w. are used, is there any cost benefits to a smaller gauge. Nor is there any significant cost increase for broader gauges, unless the vehicle width is also increased. BTW, that is not the case with BART, as its cars are actually only 10ft 6in wide at their widest point (pretty standard actually). It is the tubular shape, widest at seat level, that makes them seem so comfortable.
OPB
PS: ---- As to certain Marinites pretending to be railfans, or as anyone actually interested in railways of any sort - does anybody have a mousetrap that actually works!
