Image by Steven Dale.
True story:
While I was touring the Caracas Metrocable earlier this year, myself and my guide were joined by an elderly gentleman in our gondola. Via my guide, I asked the man how he felt about the system. Did he like it? Any complaints?
He said he loved it – except for all the time the gondolas spend in the stations.
When I looked back at my records, it appears that the man had a point. During my tour of the system, I recorded end-to-end travel times of apx. 14 minutes. 5 of those minutes were spent in the three intermediary stations, meaning more than a third of the trip is spent in stations. Dwell times were roughly 1.5 minutes at each station.
Dwell times are something the cable industry isn’t adept at handling yet and that needs to change. Based upon conversations I’ve had with cable engineers, the consensus is that dwell times can be reduced down to 20-30 seconds. Given that such dwell times have been observed in large detachable chairlifts around the world, there’s no reason to believe this isn’t true.
But for whatever reason, the industry tends to install systems with station dwell times of a minute or more.
This wasn’t something unique to Caracas, either. I witnessed similar dwell times with both the Medellin and Caracas Metrocables, suggesting this issue isn’t company specific (Poma built the Medellin system, Doppelmayr the Caracas system).
My guess is that dwell times are not something the cable industry has really actively dealt with in the past. After all, most ski lifts are point-to-point installations. Dwell times simply don’t factor into the equation on most ski hills.
Furthermore, in a ski lift situation, you probably would want dwell times of 1-2 minutes. Given all the equipment, gear and clothing skiers require, more time is needed to board and alight – especially when you consider how slow people move in ski boots.
But we’re not talking about ski hills here. We’re talking about transit and most commuters don’t wear ski boots.
64 Comments
It seems to me the key issue is going to be how you can maintain handicapped-accessibility with 20-30 second dwell times.
@ BrianTH,
“how you can maintain handicapped-accessibility with 20-30 second dwell times”
A challenge indeed. I know the vehicles can be stopped completely for disabled individuals. How this messes with the system as a whole is, however, for the engineers to comment upon.
From what I understand dwell times can be tuned to whatever the application/client needs or feels comfortable with within reason.
However some things need to be considered too:
When in the terminal/midstation cabins can only go so fast around corners and past door opening/closing actuators without wobbling around and breaking things and scaring passengers (you’re right this is an engineering problem and could be addressed if the need is there to go faster).
Next there’s the issue of how fast an object can be moving and yet still allow all riders to board and alight safely, generally for cabins this is about 0.3 m/s (chairs are faster because everyone is all lined up and ready for the chair to swoop in and grab them plus they are often on skis and skiers are allowed to load faster on chairs than foot passengers). I agree this seems slow at times…but remember are you ALL people? Also these speeds are very often dictated by existing codes and standards, how many passengers can ride in a cabin, whether it’s level-walk-in or step in, and how much room the passengers all have to board the cabin and unfortunately this often has to be the same in each terminal and midstation (see the “system” comment below), which can be crummy is most people are going top to bottom and only a few get on/off at some of the intermediate stations, making these stations seem slow.
Possible solutions here might be a moving sidewalk for a loading platform or having the cabins move faster through non-loading sections of the terminal and then come to a stand still in another part of the terminal. This has been done and is an excellent solution if several riders may have mobility issues; otherwise the solutions is to stop the lift all together when a person with an assistive device or mobility issue is boarding (incidentally in any installation you can always ask the operator to slow/stop the lift for you and they will gladly help you board).
Finally there’s the “system” issue. Since the entire ropeway is one large circulating machine all of the cabins must leave the terminal at essentially the same frequency and spacing (otherwise crummy point loading, as in forces applied to towers, and vibration issues may occur). There already exist systems to catch-up and hold back a cabin in the terminal if it’s lagging/leading the system, but currently you can’t tell the system no one wants to get off at this station…please speed on past. I guess like many transit solutions this is negative of the system that has to be taken into consideration with all of the positives.
Did you ask the man what he thought of riding the bus up the hill prior to the metro cable?
I know I hate it when my bus sits at a stop for a while so that it can “stay” on its schedule for subsequent stops, but on the other hand I love that I live in a country where the buses at least adhere to a schedule…OH! but if a cabin would swoop down every few seconds to pick me up that would be divine!
@ BC,
The whole question is to get the planners and engineers to communicate and understand one another. There has to be a happy middle ground to satisfy all parties, but I think it safe to assume that a 2 minute dwell time is excessive.
Just a random thought, but I was wondering if it would be possible to keep special handicap-accessible vehicles available off-line, which could be swapped into the sequence as needed, preloaded with the passengers in question. You wouldn’t want a bunch of these sitting in each station, so you would have to be smart about managing the supply, coordinating among the stations and so on. And it would probably still make sense to have the base system cable of handling the widest possible range of passengers, consistent with overall timely and efficient operations, such that only a few passengers needed to do this swapping.
This may be a horrible idea, but anyway, one would hope engineers and planners could make use of some of the favorable underlying characteristics of these systems (in this case, detachability and frequency of vehicles) to address these issues in innovative ways.
In general it’s possible I’d say. But those special platforms would need space again and the way to get there.
So I see them similar to cable-cabin-garages. There’s a way to get to those garages, but it takes some place. Similar to rails. I don’t think that is the right thing and I wonder if those times are really necessary.
I mean: think about tram and metro. Their stops are much shorter, but in case – they can drive a little faster in the end to remain in time.
So, if it is really not possible to enter those cabins within time, maybe the right thing is to slow the whole thing down a bit or what I’d say would be the best thing: make a real stop.
The thing about those moving cabins in the stations is that the main system of gondola traffic is about 2 stations. So unfortunately you will have those cabins always to move from one side to the other (not for aerial trams). If you can make full stops – for putting those cabins into the garage or for preventing accidents or letting handicapped people enter… then it’s not magic at all – it’s there and it’s working.
So in the end maybe it’s more practical to put a few marked cabins in the system which have a bit of a buffer in front and behind them and let only those do the slower jobs.
I think there’s room for engineering creativity here. Imagine two loops at a station – one short loop where cars bypass the station (though they still slow down for a bit), and another wider loop for passengers that get on and off. Both loops disconnect the cars from the line, and the inner loop moves at a constant rate (like a normal gondola station) while the outer loop moves at a variable rate. Now, imagine someone wants to get off – they press a button in the car and when it arrives at the station their car is placed in the wider loop. That creates a space in the smaller loop, and a leaving car joins the short loop in its place when the two loops intersect again. (this would be easier to describe with a drawing – let me know if you don’t get it)
Looking at the extremes, if everyone wants on and off, then all cars take the wider loop. If nobody wants on or off, nobody dwells for more than a few seconds. If somebody wants on, then they get in a car and wait for either someone to get off or an empty car (which can be diverted to the larger loop by an operator or some sort of motion sensor).
The result is that the only dwell time is in waiting for space to get onto the line. The line will have a constant spacing of cars (each empty space is replaced by another car). And you can take a long time to load a car if needed.
@ Matt the Engineer,
I’m having difficulties visualizing what you’re proposing. Any way you could draw it up for us?
To stop a cabin at the station is not necessary at ropeways for winter sport (wheelchair user and other handicapped persons are very rare).
The intra urban 3S Ropeway (TGD) at Bozen/Bolzano, Italy, stops at the station, but the gondola interval is 4 minutes.
If you have a dwell time of 30 seconds you need a intervall of 30 seconds too. Metrocable de Medellin runs witn an intervall of 12 seconds, ir cannot stop.
#Matt
“If somebody wants on, then they get in a car and wait for either someone to get off or an empty car”
How long would want to you wait on rush hour? Please give me a number.
And if you shorten 30 second-intervalls by “pressing a gondola into the line”, you have a 15 second intervall at the following station.
It is complicated, but solvable, I described it at my website
The time interval of the gondolas must be a little bit more than stopping time at the station. But it is complicated, if you have a gondola jam ( because a door did not shut in time), but it is solvable.
I’ve found (visiting the subway of vienna) 10 seconds are enough to get out and into a (10 persons-) gondola at a station.
[Guenther] You’d wait as long as you wait now. If the cars are occupied and nobody’s getting off, then how does it help to stop at every station?
If this is really a problem, there are ways to fix it. Forcing empty cars every now and then would be one solution. Or grouping cars by destination (just have seperate lines). Or force a
[Steven] I’ve drawn up a very basic sketch (here). Let’s assume the outer line takes an average of 2 minutes (this will obviously be variable), and the inner line takes 15 seconds.
(oops, didn’t finish my comment to [Guenther]) Or force a car to stop if it’s not fully occupied.
(looking at my sketch again, I’ve obviously drawn way too many cars. it was a very quick sketch!)
Well it’s easy to solve that problem by creating a pulsing of cars.
If you say every second gondola is to be stopped, then you will need virtual slots on the “cable”.
… 1 – 2 – 1 – 2 – ….(the distance between those isn’t discussed yet) and if a gondola gets bypassed one slot opens, which means, this one could be used for the previous gondola to enter from the bypass.
or you could do … 1 – 0 – 2 – 0 – 1 – 0 – 2 – 0 … and so on (with the minimum distance possible). In that case you are allowed to add every intervall 2 further gondolas to reach the maximum of 4 without any trouble.
Gondolas on the “cable” won’t have the same distance, the slots will. So you will have gaps between them, which is a bit strange but that’s how it is.
The real thing to handle on that is another:
1. the fixtures have to ungrab the cable and maximum speed and the gondola needs to be accelerated by something else (may it be another rope or wheels like within stations)
2. to enter the constant speed loop or the variable speed loop the guidance unit (on top of that two cables in case of 3s) has to change the tracking cables.
It’s basically point two which needs to be solved if you want to go on with that idea.
(I mentioned the same last week at another place about Guenthers schematical drawings). It’s absolutely the same problem to solve here too.
[LX] I’m not sure I understand your 1-0-2-0 case.
1. Yes. I was thinking of using a sloped track using gravity (or perhaps a cable with a variable speed drive) for most of the large loop with a cable at the very end to accelerate you onto the main cable.
2. I’m not sure I understand this point. Maybe I have to spend more time trying to figure out the details of a 3S. I had MDG in mind when thinking about this.
Still the same issue with MDG, as it is in using the ideas from number 1. I will try to take a little time within the next days and prepare some sketches of what I mean. During the time just go on with your idea.
1-0-2-0 is the interval of 4/4. 4 possible positions on a given distance (you can not load cable with any given weight – there is a maximum of possible gondolas by weight and by distance (caused by dwelling time within the station).
So you have to prepare slots within your cableline to make sure there won’t be an overload by too many cabins and there won’t be time to wait for passengers in the cabin to join the main track -> you need to find a solution for that.
That might by partitionating the capacity of a cable-track down to possible slots.
As in case of 1-0-2-0 within that part of the rope 4 cabins could be hanging, right now there are two on it (1 and 2). If cabin 1 wants to stop there are free slots within that interval to join again, while cabin 2 went by without stopping – and if the stop takes longer or from the garage more cabins are added you can use the empty ones within that interval or the next.
Crush load in that case would be 1-1-1-1: whether cabins are marked and just stop at every second, third or fourth stop and people have to choose/wait to enter the right cabin or during rush hour and crush load all cabins will stop at every stop.
Got it. But I’m not sure that’s needed under my solution. You can have all slots filled all the time. Let’s assume X is an empty car, 1 is stopping at the first stop, 2 is starting at the 2nd stop, etc. Let’s look at 4 cars from leaving the end of the line:
1-X-2-4
The left two cars (1-X) both take the wider loop at the first stop. In their place two new cars that were waiting for a space in the line. Say there was only one car worth of passengers. Leaving the first stop:
X-3-2-4
This time the left most car and the third car take the wider loop and are replaced. This time let’s assume there are 2 cars filled with passengers. Leaving the second stop:
3-3-4-4
Leaving the third stop:
X-4-4-4
There are never any empty “slots” on the line.
Having all “slots” filled with cars means later “slots” will have to be cleared which means: whether or not they want to, cars need to get out of the line to make place for waiting cars to join the line. (result would be: cars to join the line will have to wait for that empty place and cars which wouldn’t stop at that place will be forced to do that in order to let the leaving cars not wait too long).
So in the end people won’t even only have to wait for the cars/cabins to get into the station and slow down, get out/get in, accelerate and join the line – no, besides that they will have to get in cue and wait to join the line.
“There are never any empty “slots” on the line.” That means cars will run empty.
I think you’re misunderstanding. In your system, new cars can join only when there’s an empty slot or if a car is stopping at the station. In my system, new car can join only when there’s an empty car or if a car is stopping at the station. There is no difference, except in mine you’re running empty cars. But so what? I see this as always providing replacements for cars joining the line – there’s always the same number of cars in a station. In your system I could imagine running out of cars, or having too many cars.
[ Gondolas up and down a hill need constant intervals, because there is a state of equilibrium of the gondolas. A gondola riding down raises up the gondola riding up and you need only energy to transport the inertial mass and for friction losses and to raise up the passengers.
Gondolas “on plain” are rarely in a state of equilibrium, you don’t need constant intervals and you waste energy, if you transport empty gondolas. At urban ropeways the lines (direction and opposite direction) must have different drives, so you can use only the equilibrium on the same line at a sag ( a gondola riding down at a sag brings energy into the system and needs energy riding up later) ]
#Matt “ If the cars are occupied and nobody’s getting off, then how does it help to stop at every station? “
Matt, I understand it. 13 years ago I created a network of ropeways for my hometown (with about 50,000 inhabitants) and these 13 years I was alone with my ideas. I spent this long time thinking how it can be realized and I’m describing my conclusions at my website
http://www.abcde-institute.org/urban_ropeways_destination_stops.html
At rush hour you cannot find any empty gondola that stops at your destination stop, so you are waiting and waiting…
The main problem is not at the destination stop, you want to get off or in, you have the problems at following stations. You can shorten the time interval between the gondolas once, twice, but the number of these procedures is limited.
#LX: The method with slots has the disadvantage that you cannot transport the maximum of passengers, because you need empty slots and you have to produce this slots at the start station. Every gondola, stopping at a destination stop creates a new slot and integrates itself at the next slot. It looks like a fascinating and simple solution, but the devil is in the details (at following stations):
Take an interval of the gondolas of 30 seconds and every third slot is “empty”. You have numbered gondolas, ( ) = slot, for example:
–> ( )-(8)-(7)-( )-(6)-(5)-( )-(4)-(3)-( )-(2)-(1) –> direction
If your (first) gondola stops at the station, it stops 20 seconds (speed = 0 m/s) and needs 10 seconds driving inside the station. After this 30 seconds the following gondola is already inside the station (to stop or to ride through) , so the gondola has to wait 30 second (to the middle of the slot). So you need for a stop at a midstation 30+30 seconds (if the second gondola stops, you need only 30 seconds)
result: ( )-(8)-(7)-( )-(6)-(5)-( )-(4)-(3)-(1)-(2)-( )
The first gondola stops, the second gondola is riding through, the next slot is filled by the first gondola, then come the third and the fourth gondola and at the following station there is first a slot (made by the first gondola, then 4 gondolas behind each other and then the next slot. If here the “second” gondola stops, you need 30+90 seconds for a stop at a midstation. The second gondola fills the slot behind the fourth gondola, so your result is:
( )-(8)-(7)-( )-(6)-(5)-(2)-(4)-(3)-(1)-( )-( )
Worst case: If now the gondola (1) stops, they have to wait 30+150 seconds to the next slot.
Have a look to a system, every second “gondola” is a slot.
(6)-( )-(5)-( )-(4)-( )-(3)-( )-(2)-( )-(1)
Gondola (1) stops, so at the next station the gondolas come like:
(6)-( )-(5)-( )-(4)-( )-(3)-( )-(2)-(1)-( )
Gondola (1) stops again, the result is
(6)-( )-(5)-( )-(4)-( )-(3)-(1)-(2)-( )-( )
With this method the condition to find no slot comes not so fast. Probably at every fourth midstation the system must be new partitioned and here it starts to be most complicated.
problem: (6)-( )-(5)-( )-(4)-(2)-(3)-(1)-( )-( )-( )
The system inserts gondola (7),
result: (6)-( )-(5)-( )-(4)-(2)-(3)-(1)-( )-(7)-( )
To insert a new slot, all gondolas behind (1) have to wait 30 seconds. But this method slows the transport. You can choose: Waiting at a station to the next slot or waiting inside the chain, when a new slot is created.
I think, my system is easier.
My system is, that all gondolas drive through a station ( ice rink in summer, outdoor pool in winter) or all gondolas stop at this station.
To change the system from “drive through” to “stop” is no problem.
To change the system from “stop” to “drive through” is a (solvable) task.
Ok, I decided to create an animation. It’s a Google presentation – just click the forward button as fast as necessary.
(here)
Nice, but you fill the slots, too. What happened at following stations?
It’s just: people will have to wait. If there would be much more demand for Gondolas the line of that pictolized people would be incredibly long. Like in every other station we know about (to name a few with written examples on this page, Caracas, Medellin).
And with that empty slots I agree with you Guenther, it is not working out that fine – but it’s caused by the maximum capacity of load/gondolas possible on a track. If there wasn’t any, like theoratically on rails, you could fill the whole line with gondolas or trains, like a pater-noster and it would all “work” (maximum capacity and a theoretical waiting time of 0 seconds).
But that’s not how its gonna work.
Good thing is: it’s the same with every technology. If buses are full, no further person is able to join and will have to wait – and before that everybody has to wait for the bus to arrive.
@ LX,
I’ve tried to stay out of this conversation because I”m no engineer and would rather respect my limits. However:
I’ve seen how Medellin deals with the “full” cabin issue and it’s quite interesting . . . wether it is intentional or not, I’m not sure, but the principal is important:
Most people will board the system at important transfer points from other technologies. Let’s imagine a 4 station line with one station connected to a subway. Logically, the subway station will be the most important. As people move from the subway through the other 3 lines, more people will be getting off than on – but you’ll still need some available space.
Invariably, a certain percentage of the gondolas leave the “transfer” station completely empty. AFter all, once a subway has cleared, there are only so many people wishing to use the gondola. Whatever excess capacity exists opens up space for others along the line.
A possible solution:
For example, the gondola transit has one starting station, three midstations and the end station
The sequence of the gondolas is;
(4)-(3)-(2)-(1) –>
a (1) gondola stops only at station 1 and then again at station 4,
a (2) gondola stops only at station 2 and then again at station 4,
a (3) gondola stops only at station 3 and then again at station 4,
a (4) gondola stops only at station 4
First time after station 1 you have the sequence:
(4)-(3)-(2)-()
The (1) gondola at station 1 is waiting until the next (1) gondola opens a slot and then this waiting (1) gondola can start.
So the sequence remains
4)-(3)-(2)-(1)-(4)-(3)-(2)-()
and so on at every station.
a passenger riding to station 4 take a faster (4) gondola or another slower one
…If the gondolas have a time interval of 30 seconds. At every station you have about 4 x 30 seconds to get in and off; enough time.
…at every station you can start in a interval of 120 seconds;
But driving inside a gondola you cannot change your get-off destination station.
If most of the passengers get off at station 2 , for example,
the system makes a sequence like
(2)-(3)-(2)-(4)-(2)-(3)-(2)-(1).
or a different sequence. The gondola waiting time decreases at station 2.
Conclusion: At every midstation you are waiting/starting in the interval of the gondolas, driving automatically to your station.
The big advantage.
If one persons is going to a station, where seldom passengers get off or get in, he calls a gondola from the main station (=start). there starts his gondola. Or he get in a parked gondola and the main station (system) “starts a slot”.
A disadvantage: A passenger from station 1 cannot travel direct to station 3.
@Steven
Yes, you are talking about a feeder line. But why would I need some available space (or gondolas)? Like in the morning, when the first passengers will start to move to work – you might want to start with the demand of real passengers instead of saying “it’s 4.30 in the morning and we need to run our first gondola). Or during work time, after the rush is gone.
Pro for that argument: the load balance on the cable is given (not triple the load on the one side of the line than on the other), gondolas are accessable all time.
Contra: System is running at it’s maximum and empty gondolas are driven around.
Would the innovation be to make gondolas directly head towards their destination, like from (Transferstation)-(2) and not move any further but head the way back – have two of those because it’s where a lot of people live? While just one is heading (Transferstation)-(3) and back?
Or is it clever/better to have them restored at the station if not needed anymore.
Or is it better to run the whole loop from (T)-(1)-(2)-(3) and back and all of the gondolas are doing this? Or Let the gondolas be flexible by pooling the destination via counts and then make the gondola move through station 1 without stopping, when it’s supposed to take those passengers to station 2?
I think the best idea would be that pooling (means you will be recognized by the system as a passenger and your destination will be added as well with all the other passengers going towards your destination).
So a gondola within that system can be set for a specific destination and only that destination. Let’s say 6 passengers are waiting on (T) to get to (3) the system will pick a gondola and mark it’s destination on displays for (3).
6 passengers will get in at (T), maybe 2 more at (1) and because no one else is waiting at (2) to get to (3) it will without breaking/stopping go to (3).
Because of it’s flexibility I can see an unbalance (because it all will happen within a loop), but that kind of pooling already exists in elevation-technology in towers and skyscrapers – but they are all parallel.
#LX
At every midstation you are waiting/starting in the interval of the gondolas, driving automatically to your station.
And there are diffent sequences, one for the rush hour, one for the time between two rush hours, one for the evening or individual sequences (if a passenger calls a gondola)
@all
pulsing, feeder lines, double loops, etc all seem over complicated, pushing towards PRT style, and requiring of way too much space and extra mechanical parts. remember, everything done in one direction has to be mirrored for the other direction, not to mention try applying these to stacked systems, and turning stations. suddenly the cost savings soars and the space savings don’t exist.
i think we can all agree that simply speeding up a gondola in a station is not a solution because it will lead to decreased accessibility to all people.
but shorter time spent at a slow speed will decrease the dwell time and allow for easy boarding by all. just look at a subway and we all know is doesn’t take 2 full minutes to get all passengers on and off.
now, for anyone who’s seen the gondola videos of people getting on and off have probably noticed that walking on, electric scootering on, pushing a baby carriage on, wheel chairing on, are all quite possible at the current speed the cabins run through stations. (it works for almost everyone, even those with (most) mobility issues, so no need to change that.)
that leaves the number of people who would actually require a full stop to be extremely extremely low. if the issue is walking (which i can’t think of another reason), why not provide station wheel chairs or scooters. this would be just like when you go to the grocery store or airport and you are allowed usage of some sort of mobility device to ease your way through the building. (in airports, the wheel chairs even come with a nice young person to push you around.)
i think this idea would speed up dwell times, increase access, and have immense cost/space savings as opposed to many of the other very complicated and proposed methods. it’s also extremely less complicated, proven, and efficient, and can be adapted to all existing and proposed systems.
So we got:
1. A program of sequences for each day and even the possibility of individual calling
2. We do have garages with parked gondolas in every station and
3. Every station has got a quick bypass option
Excuse me but I can not see right now where this is heading to.
Making my animation was really helpful. I realized the inner loop is pointless – I’m not sure why I added it in the first place. You should be on the main rope, or on the bypass.
Like this.
@matt the engineer
yes the inner loop was redundant, but there still would be bullwheels for it, yes? is the outer loop a track or on cable? i just see this becoming an extremely large station. imagine it as a 90 degree right turn, the outer loop on the outer side would be giant!
@LX, what’s heading where?
I’m glad I’m not an engineer.
@Rose: the discussion right now.
dwell time = the time when people enter or leave the gondola. This will always be something between 10 and 20 seconds, no matter what.
Matter is the breaking and acceleration time and the speed of moving.
And yes you are right: let’s say we invented the mechanics to do that bypass and/or parking track and/or platform track, the footprint of that station would be huge.
I don’t see why it would need to be a large station. This seems like almost exactly what they do at stations currently.
@Rose. I was thinking of using a track.
Side note: I was trying to imagine how cars get on and off a track, accelerating to the right speed. I found a great picture here. They just use a set of wheels that they spin up to the right speed.
Well it is easy: take a look at the sizes of Medellin and Caracas stations, add a garage and even the bypass (I’d suggest to do that by floor plan – not schematical (again)) and then we’ve got something to talk about.
And may I get your e-mail address as well?
#Rose
You get a problem if one gondola jams, because some idiots (or passengers skipped in at the last moment) block the shutting.
You have to stop the whole system.
If every gondola has a short waiting time as a reserve, it is good.
#Matt (” I don’t see why it would need to be a large station. This seems like almost exactly what they do at stations currently.”)
You need a deceleration track and an acceleration track.
To brake from 4m/s with -1m/s² you need 26 m,
I think the destination stop track could be 10 m long.
Than you need 26 m acceleration track. So your station needs at least 62 m.
Braking from 7,5 m/s you need 66m+10m+66m = 142 m. Unpossible.
bus it is possible to shorten the station.
To accelerate gondolas at winter sport ropeways wheels are needed. But this system is not optimal.
At every gondola suspension there is a horizontal metal stripe. The wheels are riding on this stripe (the stripe is “riding” under the wheels).
One wheel has a speed, the next wheel has a faster speed and so on. There are always two wheels on a stripe, so a fluent movement results.
But one wheel is faster than the previous, so one tire surface or both are grinding. It makes a sound like skweaking of a pig. And the wheels are damaged fast and have to be changed (much work, expensive).
You see it here
http://www.youtube.com/watch?v=EhG5zMRvv_k&feature=related
at 0:30
also visible here with a good view at the rest of the mechanism:
http://www.youtube.com/watch?v=E2jVDmQFJO0
@LX
i understand what the discussion is, hence my retort.
to decrease dwell times, aka time “dwelling” in the station, move the gondola through faster… yes?
currently, as per a subway, all gondolas stop at all stops. and we see that as a problem. hence the idea of keeping some gondolas going non stop and others stopping. and the reason? so people spend less time in transit.
but what i’m saying is that everyone is proposing, as i see it, overly complicated ideas with extra programming, timing, infrastructure, etc…
as steven said, why not simply decrease a gondola dwell time, as in the time it crawls through the station, say to 30 seconds from 2 minutes. that’s a 400% decrease in time. instead of rerouting gondolas, just move them as slow as they move now, for less time. or… less dwell.
but of course there is the “problem” of accessibility. hence my proposal
@matt the engineer
the station would be larger because you would need to double the width necessary for the gondolas to move through. as i understand it most mid stations have a set of bullwheels in them, so you have that size already, plus the width of the extra track, and access to both on foot, for safety reasons. now suppose you were also making a turn, well, instead of say, having a 10m turning radius, you now have a “stopping track side” that has to span 10 additional meters out, making the whole station now a 20 m radius.
in the land of unlimited space (on a mountain) sure great no problem, but in a dense city where you are tying to decrease station size, this additional space, as i see it, is huge!
@guenther
the problem of a gondola jamming is mostly irrelevant. first off, that’s not the argument here. second, if a gondola “jams” i think there’s a bigger problem. like the jamming part. but with gondolas they now have a way to prevent cabins slipping off the cable. (this is what you mean by jamming?) sure it could happen, but it doesnt seem likely, nor do i think it would happen enough, if ever, to justify the need for a “reserve time” between cabins.
@brianth – aka the first comment, much of this came about because of accessibility.
so if we reduce the occurrence of a necessary full stop to almost never, we remove the need to bring the system, any of it, to almost never.
[LX] matt.in.wa at gmail
[Rose] has the only description that makes sense for why stations would have to be larger – an extra set of cars has to fit through. I wonder if we could do an under/over solution to save floorspace. Have cars exit at the rope level, and go through the deceleration process on their way down to a lower level. Load/unload there, then accelerate on their way back up to join the main rope.
[Guenther]
Re: accleration wheels. With the advent of variable speed drives (then the price drop involved with mass adaption) this seems like a terrible idea. Interlink all of the wheels together (same speed), then accelerate them using a single variable speed drive.
Re: length of station. It seems to me that stations would have to be this long any way you design it. People have to get on and off, right? I would also think that you could start this accel/deceleration outside the station.
that was my point. the actual dwelling time is a bit too long, but it is just the dwilling time – caused by the way it slowly has to move over. the better part for decreasing station-time is the part of acceleration and deceleration.
though the time of 2 minutes seems to me a bit too long and 30 seconds for bringing all that behind is a goal to make.
just a comparsion: dwelling time of a metro is around 10 seconds!
so if the whole station part can be minimized to 30 seconds i see almost NO point to change something about the system (well it could annoy some people to see passing by full gondolas with an open door and no ability for them to enter those -> have to wait longer).
but i doubt reaching that times with that technology.
rose, regarding your first 2 sentences towards guenther: it IS the most relevant factor within the station and also the biggest problem. due to its mechanism there is no other reason for stopping/jamming the system.
@LX
maybe i misunderstand your use of the word “jam” … i was thinking of a door jam, like if there was a problem and the whole system had to be stopped.
but i guess if what he means is that if the doors try to close and a person is stuck then … jam.
but i propose we fix that with marked spaces for entry and other indications to make sure that doesn’t happen (or at least helps prevent it), or look to how other modes of automatic transportation fix this issue.
@matt
i was thinking that too! because, hey-o if there’s one thing we know gondolas can do its go up and down. but i’m also thinking, in terms of station profile this could be huge, and the cost/time savings of going up and over might be negligible if station dwell time could just be reduced.
at least at this point there are maybe 3 or 4 midstations per line, tops, right? so to save 2 minutes (30 seconds per station), there are a lot of parts/components/places things could go wrong. (plus you probably still need to spend a minute or so avoiding the station) instead i it might make more sense to focus on making the system as a whole go faster, and put the R&D into that. then the travel times are shorter for everyone!
also, something as simple as a larger door or multiple exit doors in a gondola could make the flow of passengers in an out of a cabin quicker, so who knows, maybe soon we’ll have 10 second dwell times and we will all be hopping out of vehicles just as we do at subway platforms.
A gondola jam is, if a gondola is at the station, there are problems to shut the doors and the next gondola is arriving at the station.
At winter sport ropeways the gondolas arrive at the station, they brake to 0,5 m/s, the doors open, passengers get off, the gondola drives with this slow speed on the rail from the get-off point around to the get-in point, passengers enter the cabin, the doors are still open, the gondola moves to the starting point, no more passengers enter here the cabin, then the doors shut, some seconds later the gondola starts.
If you optimize the dwelling time you have to shorten each procedure.
The gondola drives with about 2m/s to the stopping place and brakes to 0 m/s, the doors open for 10 seconds, the doors shut, the gondola starts. 2 seconds later ( ! ) the next gondola stops at the stopping place.
If you have a problem with the doors (it isn’t seldom at subways or winter sport ropeways) you have a JAM and a BIG PROBLEM. If you have a time reserve, you could solve the problem. And there is no problem with accessibility by handicapped persons.
The following gondola could wait at a jam track, of course, but the jamming gondola doesn’t start, the interval to the third (driving through?) gondola decreases,…Like a car jam at a street, the jam moves backwards, you have to stop the whole system.
If you stop a driving rope, the rope and the cabins start to swing (could be a problem at re-starting) and the passengers lose time and are perhaps frightened. By all means a stop of the rope must be avoided at urban ropeways !
Mid stations don’t need a bullwheel, what is it used for? Only if the arrival direction has a separated drive and the exit direction too ( it would be better).
To start deceleration/acceleration outside a station it is too expensive. Detachable ropeways with one rope can drive only up to a side wind of 65-70 km/h, detachable ropeways with two (hauling or support) cables can drive up to a wind of 100 km/h. You cannot stop an urban transportation system, because “sorry, today is the wind stronger”. So it is better to move gondolas on two ropes and with this systems (3S, Funitel) the towers are very very expensive. But you need two towers with bullwheels to return the de/acceleration ropes. Deceleration/acceleration outside a station is a nice idea, but too expensive. Why a gondola must be faster than a tram?
Guys, before I have to copy my whole website here, please TAKE YOUR TIME and read a little bit there:
http://www.abcde-institute.org/urban_ropeways_destination_stops.html
so we can discuss at the same eye level (don’t be angry about me).
Regarding loops in stations…not to feed the flames here…but check out page 2 of the most recent issue of WIR magazine.
http://www.doppelmayrctec.com/uploads/media/WIR_183_Englisch.pdf
Here Doppelmayr has designed two loops to handle the mixed chair and gondola traffic on one of their “kombi” or “chondola” lifts. Granted this solution only applies to end stations, and granted as @Rose points out it’s more complicated, but I point this out to highlight the switching rail idea is completely possible as @Matt the engineer and @LX are working on.
and yes @Steven Dale 2 minutes seems huge…I’m not sure why that’s so long but probably has to do with the length of the mid stations versus cabin spacing (they seem like huge stations in the pictures and the spacing is very dense) together with how they’ve laid out the machinery in the stations versus passenger traffic flow…yes they could have made the load/unload sections shorter and the lengthened the accel/decel sections but they didn’t for some reason. I suppose if they wanted to change this they could change the diameter of the v-belt pulleys that are powering the individual wheels that drive the cabins around the track so that some sections will be rolling faster versus how they are now (this could mean less overall cabins too…this is what I mean by “tuned” to how the customer/regional code wants the lift to run).
[BC] That’ll do it. I don’t see any reason that can’t be done at a middle station.
That magazine’s a great resource. I’m very impressed by the 3.5 mile long tram with only 3 towers.
[BC] Very nice to see it before it is online published (in the pull-down-menu). You are an insider.
We can read at the magazine “The gondolas have a station transit speed of 0.15 m/s”.
“2 minutes seems huge”.
The giondolas drives 18 m in 2 minutes
( 9 m at the arriving platform and 9 m at the exit platform).
[Guenther Ecker] you’re right!…18m at 0.15 m/s will do it. Nice job. I’m more used to gondolas traveling at 0.3 m/s in stations which is as fast as I think I’d ever want them to go while loading/unloading. And yet the cabins have to travel that distance one way or another. It’s true, and I think [LX] suggested it, (please correct me if I’m crediting the wrong person) it would be nice if the cabin would quickly stop for 20 sec to unload…then advance…stop for 20 sec to load and then get on its way.
i don’t believe the issue was ever if 2 loops could be done, but rather, if 2 loops should be done. i think it’s still heavily a space and money issue. if the only way to solve dwell times is with that much extra infrastructure the flexibility of gondola technology is severely decreased, most notably in terms of the idea of small footprint stations in cities. as in, it would no longer be able to say “we can go almost anywhere”, but rather “we could go almost anywhere … as long as you have X by Y amount of space”
now, as an end station, the diagram makes the design look pretty slim, small, and not too cumbersome, but stretch that out to a straight line, and suddenly you have to pick between giant station with short dwell or little station with long commute times… either way i don’t think it will sell in NA/Euro markets, which would bring us all right back to the same problem, but after significant amounts spent in R&D.
[BC]
What is the fastest deceleration [- m/s²] and the fastest acceleration [ m/s² ] gondolas drive at a station?
[Rose]
One advantage of gondola transit is, that you can take it as a transportation system in cities of developing countries with not enough space for trams or buses, and in this case you have not enough space for large gondola stations.
If you have to integrate the stations into an existing town structure at traffic junctions/road crossings, you haven’t much space, too. Not even the station is above the cars on the first floor (townscape problem). You find space for tracks for Urban Ropeways only at the side of roads, but they should not drive above the rooftops (rescuing problems).
In town you must have small stations, especially the stations are midstations !
[Guenther Ecker ]
I’m not sure about other countries but the Canadian code (CSA Z98-07) says that “The rate of the carrier’s acceleration to and deceleration from the design haul rope speed shall not exceed 2.4 m/s2 under **the most adverse braking conditions**” (emphasis mine).
General accel/decel is done more gradually over 8-15m long sections depending on the size of the carriers/terminal and is based more on passenger comfort…and I bet in the transit field there are codes that govern this too since riders are often standing or sitting without seat belts.
Does anyone know what other standards may be in force here?
guenther, why are you telling me what i already said?
@GE “Mid stations don’t need a bullwheel, what is it used for?”
Midstations very often join two gondola ropeway turnarounds endwise coupled by a conveyor. This is due to inherent limitations of rope length variation due to load and temperature changes and rope stretch over time – “tensioning”.
It is true however that if the overall distance of the system isn’t extremely long then the bullwheels can be eliminated and the station can decouple cabins simply through accel/decel conveyors only.