Bogotá bus rapid transit

[ozbob]

PRI --> 8 million people. No subway. Can this city thrive without one?

Every large city has traffic headaches. And at some point the debate begins: to build or not to build a subway. In Bogotá, they've been having this argument about traffic and a subway for some 60 years.

>> http://www.pri.org/stories/2015-10-21/can-modern-megacity-bogot-get-without-subway

[ozbob]

^

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Bruce Erwin ‏@Bruchesco 11h

@robert_dow @railbotforum Rob I live in Bogota. That story was pretty accurate.

Sadly as good as transmilenio is they did it on the cheap.

[colinw]

Does TransMilenio run completely dedicated corridor without interfaces with traffic at intersections?

if it does, then using those bus lanes for above ground light metro might be the way to go.  Or even building elevated light metro (Vancouver Skytrain style) above the bus lanes.

[hU0N]

Anything with the word "light" in it isn't going to cut it I'd say. Transmilenio currently carries around 41,000 pphpd on each line during rush hour (for comparison, that's more than twice the capacity of a citytrain track pair). Granted that's partly because Colombia defines "bus full" as every seat taken plus six standees per square meter of standing space. But even with a first world definition (such as every seat plus two standees per square meter), it's estimated the system would be good for 28,000 ppdph.

Transmillenio uses buses to their particular strength, particularly the ability to run much much shorter headways than alternative types of vehicle. All fixed guideway technologies suffer from relatively poor headways which they make up for with larger vehicles. When you are talking about a bus system with the large capacity of Transmilenio, nothing short of full heavy rail is a viable alternative.

[colinw]

Bloody hell!!! Ok, if its at that level of use (or "first world" equivalent is 28K ppdh) then light metro won't cut it.  Normal light metro standard is in the 20K region, with best systems at 30K.

Nothing short of a full blown metro, underground or above, will cut it, and they had best keep the busways as well.

[#Metro]

Increase the price of tickets. That will free up some space.

[#Metro]

I went to YouTube, and found a video. It seems like they are suffering from the 'Brisbane disease'.
The video is in Spanish, but if you go to YouTube settings, you can have the captions shown and autotranslated in English.

The problem the video is suggesting is overall bus network design.

[hU0N]

IIRC I think that the cost is already quite high. As in daily tickets cost somewhere in the vicinity of 1/3 of the average daily wage for a day labourer (ie the sort of worker we'd call minimum wage in the first world).

As for network design, I don't know much about the details, but I'm almost certain that it's a closed busway trunk-and-feeder design with cross platform transfers to out of system local feeder buses at certain stations. Part of the problem is that they have given in to the temptation to run complicated skip stop express patterns to squeeze an extra 30% capacity out of the fact that bus headways are quite a bit shorter than station dwell times.

The option to run this sort of pattern is fairly unique to BRT. Heavy rail has minimum headways that are typically longer than minimum station dwell times, and while LRT is similar to BRT in the headway vs dwell time department, actually implementing skip stop operation to take advantage of it is prohibitively tricky or expensive or both.

As such, I don't know if there are enough comparative examples to say whether this type of pattern works best for Bogota or not. One thing I am certain of is that the problem is a little different to Brisbane. Here we prioritise one seat coverage over legibility or capacity. In Bogota, capacity is king.