LOS ANGELES | Transportation News & Discussion

[caligrad]

Well I hope Metro looks into elevated HRT lines. Not for downtown or the mid city area but for anything south of the 10, east of the river and in the valley (only needs 1 or 2 HRT lines). I feel this is a better solution than slapping us with LRT that is sluggish and subways in low density areas. The system could be like the Bart. Comes out of the ground and is elevated in low density areas but goes under in the high density areas. Downtown, the Central/Century city and Westside need nothing but subways at this point in my opinion.

[Will O' Wisp]

Originally Posted by Quixote

That's not an apples-to-apples comparison.

As Illithid Dude already mentioned, the turnback facility being constructed as part of the Purple Line extension will allow for 4-minute headways on both the Purple and Red Lines--the interlined trunk having trains come every 2 minutes. Hell, if it wasn't for the interlining, you could have 2-minute headways because the full grade-separation allows it.

So HRT has a maximum capacity of 54,180 riders per hour (over 8x that of LRT). For 4-minute headways, it's 27,090 riders per hour.

Very true, but that doesn't necessarily give the "win" to HRT. With 4 minute headways HRT is still less cost effective than LRT (4x the capacity for 5x the price), it isn't until you reach 2 minute headways that HRT starts to pull ahead. And even then I'm actually being a bit generous to HRT here, this is for crush loads which give it a more competitive edge. Crush capacity is 218 vs 301 riders per car instead of 164 vs 180 at full load (giving HRT 138% of LRT's capacity vs 109%). So the only way HRT is truly cost competitive is with 2 minute headways at crush capacities, and that opens the question of exactly how many routes in LA can put up those numbers on a regular basis.

This is very back-of-the-napkin style price considerations of course, there's a ton more math than just capital costs and capacity, but for the most part any potential new HRT line has to justify why ridership would make LRT unfeasible along that corridor. Yes LRT is 5x more cost effective than HRT, but you can't exactly put three LRT lines down Wilshire Blvd even if the math says it would save you a few billion dollars.

[WrightCONCEPT]

Originally Posted by jmecklenborg

Most heavy rail rapid transit trains are wider than light rail trains and so have a higher standing crush capacity. Also, the capacity of the same train in Asia has a higher crush capacity because Americans are big and fat.

Actually there are a number of heavy rail trains that are the same width as some light rail trains, like in some of the older Metro lines in Europe and Asia.

[WrightCONCEPT]

Originally Posted by jmecklenborg

I remember a long time ago someone offering the simple rule of thumb that elevated is 2x what surface costs, and subway is 3x the cost of surface.

The structure that supports heavy rail obviously needs to be more robust than one that supports light rail, but I don't know why HRT subway is more expensive than LRT subway, other than the use of a somewhat wider bore.

The rule of thumb according to "Urban Transportation Systems" for both light rail and heavy rail construction alignments are;

• Elevated is 2x to 3x the cost of surface.
• Open-Air Trenches are 5x the cost of surface, 2x the cost of elevated.
• Subways are 3x to 4x the cost of elevated and 6x to 12x the cost of surface. If the subsurface issues are difficult for a subway that cost multiplier increases.

[Busy Bee]

Not wanting to "derail" the conversation, but seeing the cost breakdown above, I have to ask what is the dominant cost related to open-air trench construction? Is is the earth-moving/excavation, utility removal, water table issues?

[WrightCONCEPT]

Originally Posted by Busy Bee

Not wanting to "derail" the conversation, but seeing the cost breakdown above, I have to ask what is the dominant cost related to open-air trench construction? Is is the earth-moving/excavation, utility removal, water table issues?

Exactly, Open Air trenches depending on how deep they are built are essentially constructed like a cut-cover subway would be except you are not covering the top of the tunnel.

[caligrad]

And I would assume in earthquake country, the extra bracing needed would make the price skyrocket. I think a good example of that is the Alameda Corridor

https://en.wikipedia.org/wiki/Alameda_Corridor

[Will O' Wisp]

Originally Posted by caligrad

And I would assume in earthquake country, the extra bracing needed would make the price skyrocket. I think a good example of that is the Alameda Corridor

https://en.wikipedia.org/wiki/Alameda_Corridor

This is a bit anecdotal, but I used to live next to the Alameda Corridor and the congestion trying to pass from one side to the other was horrible (exacerbated by 710 dead ending on Valley Blvd). For that reason alone I tend to be a little suspicious of open cuts, they can divide up a community just as bad as a freeway sometimes.

[Busy Bee]

Originally Posted by caligrad

And I would assume in earthquake country, the extra bracing needed would make the price skyrocket. I think a good example of that is the Alameda Corridor

https://en.wikipedia.org/wiki/Alameda_Corridor

Are you sure that's what they are for? How come the newer San Gabriel extension doesn't have them?

[hughfb3]

Originally Posted by Will O' Wisp

Very true, but that doesn't necessarily give the "win" to HRT. With 4 minute headways HRT is still less cost effective than LRT (4x the capacity for 5x the price), it isn't until you reach 2 minute headways that HRT starts to pull ahead. And even then I'm actually being a bit generous to HRT here, this is for crush loads which give it a more competitive edge. Crush capacity is 218 vs 301 riders per car instead of 164 vs 180 at full load (giving HRT 138% of LRT's capacity vs 109%). So the only way HRT is truly cost competitive is with 2 minute headways at crush capacities, and that opens the question of exactly how many routes in LA can put up those numbers on a regular basis.

This is very back-of-the-napkin style price considerations of course, there's a ton more math than just capital costs and capacity, but for the most part any potential new HRT line has to justify why ridership would make LRT unfeasible along that corridor. Yes LRT is 5x more cost effective than HRT, but you can't exactly put three LRT lines down Wilshire Blvd even if the math says it would save you a few billion dollars.

I love this discussion and thank you for bringing it up. I believe from a cost benefit, Light Rail is only good for small to medium sized areas like the gold line from Pasadena on where it has right of way and signal priority to truly be fast. We can see that public transit ridership has been on The decline for a couple years in the midst of an expanding economy; even with us building more and more light rail lines. The trend that I’m seeing is that if light rail isn’t fast enough to buffer the system as a whole for when the economy is doing well, then when people can afford to buy a car, they do. The only way public transit is effective all the time is if it is truly the fastest way to get places. When it takes people the same, if not slower amount of time on public transit, we will opt for the car. Why would anyone ride public transit unless it is truly the fastest way sans economy.

Again...It all depends on the speed of the system as a whole, bus, rail and in between. Looking at speed line by line could be a “getcha gotcha.”

[ardecila]

Originally Posted by Busy Bee

Are you sure that's what they are for? How come the newer San Gabriel extension doesn't have them?

The retaining walls need some kind of feature to resist soil pressure and other forces, seismic among them. The struts covering the top of the trench are not purely to resist seismic forces, if you picked up the Alameda Corridor and dropped it in Southside Chicago with (presumably) zero seismic risk, you would still need those struts or some similar feature to prevent the walls from falling.

The old-school approach used on historic railroad structures is usually a gravity wall, the wall just gets thicker and thicker towards the bottom and thus resists forces, but this doesn't work if your trench is hemmed in by adjacent buildings, roadway, etc and you need to squeeze every last inch of "right of way" down at the bottom. It's also not the greenest approach, as it requires a much much larger volume of concrete and the associated carbon emissions.

Apparently UP refused the use of struts for the San Gabriel trench, so they sank tiebacks into the surrounding soil instead. This approach is more costly and probably requires the purchase of subsurface rights from adjacent landowners. It's always preferable to resolve engineering issues within the confines of your site...

[Busy Bee]

Strange. You'd think a sheet piling of a certain thickness, certain depth and maybe with concrete caps would be enough even without concrete wall or struts. Are we sure these trenches aren't being over-engineered?

[caligrad]

Like Ardecila said, they are there for a lot of factors with Seismic forces being one of them. Its better to be safe than sorry. Especially when things tend to fail in this country, citizens tend to overreact and grab pitchforks trying to banish anything similar in the future. Like the mess with the red/purple lines being built in the 80s and 90s. Every time something went wrong like the Sinkhole situation in Hollywood and methane explosion on Wilshire, everybody overreacted and we haven't started tunneling again until recently. So im sure its a better safe than sorry situation more so than being over engineered.

[hughfb3]

When in 1981; San Diego launched the first modern day Light Rail system in America, they had construction costs of $10 Million per mile. Light Rail fever then swept the nation as a cheap alternative to build rail and reinvigorate neighborhoods. Since then those costs have skyrocketed for various reasons (more grade separations because increased street traffic, land costs, etc.) With an average speed of 30-35mph and medium capacity, is light rail still all that its cracked up to be?? Should we be looking at other alternatives that come designed and cost effective at being grade separated? If light rail is no longer valid at being at grade, then is there still a point in this type of transit that we ripped up 70 years ago?

In LA, since its inception, we have been building less and less mileage in a single phase while costs have ballooned. Even adjusting for inflation doesnt seem to justify this cost increase.

[IMG][/IMG]

Miles opened in single phase
1990 Blue Line 22
1995 Green Line 20
2003 Gold Line Union-Pas 13.7
2016 Gold Line Pas-Azusa 11.5
2012 Expo Line 8.6
2016 Expo Line 6.6
2019 Crenshaw I 8.5
(?year) Gold Line East Whittier 6.75
(year?) Gold Line East 60 9.09
2021 Regional Connector 1.9
probable future (joke) 0.001


Cost per mile (millions) Cost per mile (adj Inflation millions)
1990 Blue Line $39 $75
1995 Green Line $35 $57
2003 Gold Line Union-Pas $58.40 $79.85
2016 Gold Line Pas-Azusa $63 $66
2012 Expo I $114 $125
2016 Expo II $227 $238
2019 Crenshaw I $207 $207
Gold Line East 60+Whittier $378.79 $378.79

Regional Connector $921.00 $921.00

probable almost certain future $1,500

[NSMP]

It’s because you’re not accounting for the difference in cost by grade, nor costs of ROW acquisition, and, less importantly, for scope creep.

Without controlling for the difference in subway, aerial, and at grade, these comparisons are de facto invalid. Meanwhile, it should be self-evident that the cost of ROW acquisition has risen faster than inflation.

[hughfb3]

Originally Posted by NSMP

It’s because you’re not accounting for the difference in cost by grade, nor costs of ROW acquisition, and, less importantly, for scope creep.

Without controlling for the difference in subway, aerial, and at grade, these comparisons are de facto invalid. Meanwhile, it should be self-evident that the cost of ROW acquisition has risen faster than inflation.

Actually those are the direct issues I’m speaking of when relating to Light Rail. By some metrics, LA has some of the most expensive operating costs for rail transit in the entire world. We are the biggest city in the world with the largest light rail (not Streetcar) system. There may be a correlation to the high cost of operating crash prone, non automated, grade-changing (not grade-separated) Light rail in one of the largest metropolises on the planet.

Why do Light Rail when the costs are almost on par with new technologies like fully automated subway systems constructed with Single-Bore tunnel technique (Barcelona), or automated high speed monorail (not maglev), or automated skytrain like Vancouver?

https://urbanize.la/post/whats-behin...perating-costs

[Jun]

I really wish we'd spend more money on double tracking and grade separating tracks for metrolink. Faster and more frequent service would entice more people out of their cars.

[ardecila]

Originally Posted by Busy Bee

Strange. You'd think a sheet piling of a certain thickness, certain depth and maybe with concrete caps would be enough even without concrete wall or struts. Are we sure these trenches aren't being over-engineered?

Nope. Even when you see a freestanding sheet pile wall, it often has tiebacks buried in the soil behind it and possibly horizontal whaler beams to link the tiebacks with the wall. For a trench like the Alameda corridor, or, say, a basement excavation, you have two opposing retaining walls, so you can use temporary or permanent struts spanning the excavation so that the soil pressures balance each other out. This is cheaper and easier than installing tiebacks, but can be unsightly.

I don't think UP cared about the aesthetics at San Gabriel, more likely they rejected struts and insisted on more costly tiebacks out of some concern over vertical clearances or emergency access.

[Busy Bee]

Interesting.

I wonder what method the UP trench through downtown Reno, NV used:


_

[WrightCONCEPT]

Originally Posted by hughfb3

When in 1981; San Diego launched the first modern day Light Rail system in America, they had construction costs of $10 Million per mile. Light Rail fever then swept the nation as a cheap alternative to build rail and reinvigorate neighborhoods. Since then those costs have skyrocketed for various reasons (more grade separations because increased street traffic, land costs, etc.) With an average speed of 30-35mph and medium capacity, is light rail still all that its cracked up to be?? Should we be looking at other alternatives that come designed and cost effective at being grade separated? If light rail is no longer valid at being at grade, then is there still a point in this type of transit that we ripped up 70 years ago?

In LA, since its inception, we have been building less and less mileage in a single phase while costs have ballooned. Even adjusting for inflation doesnt seem to justify this cost increase.
Miles opened in single phase
1990 Blue Line 22
1995 Green Line 20
2003 Gold Line Union-Pas 13.7
2016 Gold Line Pas-Azusa 11.5
2012 Expo Line 8.6
2016 Expo Line 6.6
2019 Crenshaw I 8.5
(?year) Gold Line East Whittier 6.75
(year?) Gold Line East 60 9.09
2021 Regional Connector 1.9

What has been the cost inflation for heavy rail subways and grade separated systems? Its exponentially gotten more expensive as well so it is a facile argument. Because that is what inflation does, it escalates costs. This would be the same concern for elevated rail system, monorail, etc.

Cost have gotten up, all over North America this has been the case as many cities/regions started with a bargain basement line that shows to taxpayers that they can deliver on something and then as the lines needed to expand the extensions have been shorter because they need to jump through environmental hoops in studies and reports in both within their states and federally to receive competitive grant dollars.

With in LA County because of the Countywide Sales Taxes and lessons learned from the past, they are going to a more Pre-Metro LRT style system so that more lines can be build all over the county and if there is a cost over run its minuscule in comparison to the system we are building. If it was all subway in one area of the system like what was done in the 1990's it would leave little room for the rest of the county to benefit from the sales tax.

What is neglected in the operational cost are the security needed for those lines which account in some years to contributing to 20-25% of the cost of operating the light rail. The Red and Purple Line does not have such cost escalation because there is less of it built, but I would wager when we have more of the heavy rail lines extended this cost would go up as well.