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Old May 21st, 2016, 09:51 PM   #2141
LastGammal
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Quote:
Originally Posted by Slartibartfas View Post
More precise numbers are talking about 47-48 min. To be honest, I am not shocked by that time, given the distance. But a proper subway would could have been faster of course. But its of no avail to discuss at this point anymore. What makes sense however is to discuss trafic light control along the Expo line. I heard there is still some potential left untouched. My question would be, what would be the possible impact of the best case scenario? By how many minutes could the ride be shortened from Santa Monica to Downtown?
How many trafficlights are there? I read somewhere (LA Times story?) that each lightcycle took about 1 minute. So if there's a 50% chance you have green light and 50% chance you have red (with 0-60 second wait=30 seconds average). Then the average lost time per traffic light would be 15 seconds.

So 10 trafficlights always being green would cut the traveltime around 2½ minute.

I guess there's also some time lost for breaking and accelerating.

But unless there's a huge number of lights I don't see this doing much of a difference.
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Old May 22nd, 2016, 02:23 AM   #2142
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Originally Posted by LastGammal View Post
I guess there's also some time lost for breaking and accelerating.

But unless there's a huge number of lights I don't see this doing much of a difference.
Light timing can actually make a huge difference. Just as an example, when Minneapolis-St. Paul's Green Line opened, the city of St. Paul refused to turn on the installed signal priority system in the fear that the system would bring other traffic to a standstill. Once St. Paul saw that traffic armageddon was not upon them, optimizing the signal priority and light timing reduced some travel times by over ten minutes (60+ minutes down to the scheduled 48 minutes and sometimes even lower). Even though it's a different context, I think that just goes to show how valuable fixes like signaling can be.
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Old May 22nd, 2016, 11:15 AM   #2143
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How many trafficlights are there? I read somewhere (LA Times story?) that each lightcycle took about 1 minute. So if there's a 50% chance you have green light and 50% chance you have red (with 0-60 second wait=30 seconds average). Then the average lost time per traffic light would be 15 seconds.

So 10 trafficlights always being green would cut the traveltime around 2½ minute.

I guess there's also some time lost for breaking and accelerating.

But unless there's a huge number of lights I don't see this doing much of a difference.
All of them have a 1 minute cycle? That sounds pretty fast to me but I have little experience with it, so maybe it's normal. With accelerating and breaking I guess the time loos could be possibly doubled compared to the mere waiting time. So we might talk about possibly 5 min for 10 traffic lights.

In the comments at the petition site, someone claimed travel times could go down as much as to 35 mins. I don't know if that is only wishfull thinking or if the potentiall is really that great. What one should certainly not underestimate is the psychological aspect. Frequent stops at non-station halts make the ride also feel a lot slower.
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Old May 22nd, 2016, 05:27 PM   #2144
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Are any underground extensions plannned?
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Old May 22nd, 2016, 07:46 PM   #2145
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What one should certainly not underestimate is the psychological aspect. Frequent stops at non-station halts make the ride also feel a lot slower.
I think this is the real issue. If the trip takes 43 or 47 minutes doesn't really matter. But randomly sitting still a couple of minutes makes it seem much slower.

I'm not sure why they can't tell how much time they would save though. Should be easy enough to test.
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Old May 22nd, 2016, 08:23 PM   #2146
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Are any underground extensions plannned?

The NEC tax measures passes a subway spur on Vermont Avenue is expected
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Old May 22nd, 2016, 09:54 PM   #2147
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I hope they will eventually put all the street-running portions underground and will eliminate more and more street crossings. The current travel time isn't really acceptable, IMO.
The green line is quite a bit longer than the Expo line and still much faster. While a big part of the speed difference is the fewer stops/mile, a lot must be the grade seperation and the thusly higher top speed itself. The entirety of the green line takes 34 mins according to Google Maps. That's an average speed of more than 56km/h. If the Expo line were that fast, 7th to DT Santa Monica would take less than 30 minutes.*

*I can't guarantee that the math is completely correct.
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Old May 23rd, 2016, 12:25 AM   #2148
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I finally had the chance to ride and film the Getty Center tram. It's one of just a few systems like this in the world that uses a cusion of air to lift the vehicle instead of wheels, similar to air hockey or a hovercraft. I wish there was a more efficient way to propel the vehicle instead of cables.

Thanks for posting! The cable propulsion is actually very efficient. The downhill tram powers the uphill tram.
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Old May 23rd, 2016, 12:31 AM   #2149
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Can anyone please tell me what's the cheapest way to travel from LAX to Santa Barbara? Thanks.
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Old May 23rd, 2016, 12:43 AM   #2150
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Riding Metro Expo Line to Santa Monica

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Old May 23rd, 2016, 12:50 AM   #2151
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Regarding travel times on the Expo Line, I have seen the following comparison.

Red Line Metro - Downtown to North Hollywood
Distance: 14.8 miles
Time: 29 minutes

Expo Line Light Rail - Downtown to Santa Monica
Distance: 15.2 miles
Time: 50 minutes

Beyond the slow travel times, the light rail lines are limited in capacity. The length of trains is limited by the distance between cross streets bracketing at-grade stations. The train frequency is limited by the frequency of disruption of traffic light cycles where signal priority is used. There have been predictions that the Expo Line will reach capacity very quickly.

One added benefit of the Expo Line that hasn't received much mention is the bike path that parallels it. My understanding is that the bike path is not yet complete and there is still at least one major gap in the route.
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Old May 23rd, 2016, 01:11 AM   #2152
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Regarding the Expo line's speed: In the current setting (47 min DT to Santa Monica), it is driving at an avarage speed of 31 km/h. Compare that to the U1 line of the Viennese U-Bahn network with an average speed of 34 km/h. The green line of course has an awesome average speed of almost 60 km/h but also the widest station spacing additionally to its full grade seperation.

I think other than grade seperation, the most important speed factor is the number stations. That would explain at least the differences in speed among those 3.

PS: Those maps might have been posted here already in before, but I find them most interesting.


http://thesource.metro.net/2010/10/0...transit-lines/


http://thesource.metro.net/2010/10/0...transit-lines/

This shows that the Expo line is a good thing but the primary west connection would be the subway to the sea, ie the purple line. In fact it is mind boggling how this wasn't one of the first extensions to be built, after the red line. (Yes I know the stories about accidents, lack of funding and nimbyism ...)
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Last edited by Slartibartfas; May 23rd, 2016 at 01:46 AM.
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Old May 23rd, 2016, 01:44 PM   #2153
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Quote:
Originally Posted by Slartibartfas View Post
Regarding the Expo line's speed: In the current setting (47 min DT to Santa Monica), it is driving at an avarage speed of 31 km/h. Compare that to the U1 line of the Viennese U-Bahn network with an average speed of 34 km/h. ...
Sure, but:
U1 (Wien) - 14,6km and 19 stations
Expo - 24,5km - 19 stations.
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Old May 23rd, 2016, 08:57 PM   #2154
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Sure, I pointed in this direction already above. Station spacing is a major speed defining factor, next to grade seperation and choice of system. I found it merely interesting to compare the speeds.
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Old May 23rd, 2016, 09:28 PM   #2155
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Originally Posted by greg_christine View Post
Thanks for posting! The cable propulsion is actually very efficient. The downhill tram powers the uphill tram.
The trams run independently of each other, so I don't believe they take advantage of the pulley system. When I was standing trackside I noticed that one cable started moving about 15 seconds before the other cable started moving. Cable systems are great for extreme grades but I fully believe that maglev or LIM systems would be more efficient (and flexible) than cable for a system like this.
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Old May 23rd, 2016, 10:03 PM   #2156
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How do you even manage ending up like this?

Car on the Expo line.


http://cdn.abclocal.go.com/content/k...96_630x354.jpg
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Old May 23rd, 2016, 10:06 PM   #2157
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Either drunkenness, severe distraction, or criminal pursuit.
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Old May 23rd, 2016, 10:22 PM   #2158
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Are any underground extensions plannned?
If and when the (currently under construction) Crenshaw Line is extended north from Expo/Crenshaw it will almost certainly be underground, probably intersecting with the future Purple Line station at Wilshire/La Brea and perhaps continuing on to meet the Red Line at Hollywood/Highland.

The entirety of the Purple Line "subway to the sea" (12 new stations, probably) will be underground.
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Old May 23rd, 2016, 10:29 PM   #2159
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Quote:
Originally Posted by Slartibartfas View Post
Regarding the Expo line's speed: In the current setting (47 min DT to Santa Monica), it is driving at an avarage speed of 31 km/h. Compare that to the U1 line of the Viennese U-Bahn network with an average speed of 34 km/h. The green line of course has an awesome average speed of almost 60 km/h but also the widest station spacing additionally to its full grade seperation.

I think other than grade seperation, the most important speed factor is the number stations. That would explain at least the differences in speed among those 3.

PS: Those maps might have been posted here already in before, but I find them most interesting.

This shows that the Expo line is a good thing but the primary west connection would be the subway to the sea, ie the purple line. In fact it is mind boggling how this wasn't one of the first extensions to be built, after the red line. (Yes I know the stories about accidents, lack of funding and nimbyism ...)
Thank you for the informative answers! It's nice to hear some factual numbers about how the system works.

I deleted your maps just so there wouldn't be duplicates on the page, but they are VERY telling. In terms of population density, employment density, and connecting the two, it's pretty clear that the purple line (future "C" line) is by far the most important line under development, and will be THE transformative piece of the rail network in the future. In fact looking at your maps it's more than ever clear that they have to actually get the purple line to santa monica in order for it to fulfill it's potential, as opposed to stopping at the VA hospital. Again, like you say it's mindboggling that this subway line hasn't been built sooner, but that's westside NIMBY's for you.
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Old May 23rd, 2016, 10:31 PM   #2160
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Quote:
Originally Posted by greg_christine View Post
Regarding travel times on the Expo Line, I have seen the following comparison.
Beyond the slow travel times, the light rail lines are limited in capacity. The length of trains is limited by the distance between cross streets bracketing at-grade stations. The train frequency is limited by the frequency of disruption of traffic light cycles where signal priority is used. There have been predictions that the Expo Line will reach capacity very quickly.
I'm glad that LA is getting so much done, but they had really ought to take a second look at some of their mode choices. If they're going to continue to use as much light rail as the backbone of the system as they propose (rather unprecedented for a city of their size), they had ought to work on grade-separating it as much as possible. Street-running sections should definitely be minimal to avoid conflicts with street traffic and allow greater train (and thus passenger) throughput.
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