Is the real problem with running LRT at grade from Arbutus to UBC not capacity, but rather the execution risk of not achieving the promised headway design?
Let me explain:
I think the real reason people don't design lrt for shorter headways with at grade crossings is the amount of engineering that is required to get it right. In other worlds, getting the capacity of light rail at grade is not a theoretical or practical issue, it's execution issue.
This capacity risk (of not getting the right headway), if not mitigated correctly, based on how risky it is and what happens if failure occurs, can derail the project. (For example: Let's design 2 minute headways with CBTC (for example as Eglinton Crosstown project is doing this with 3 minute headways that I know of with a link supplied later to this).OK .can we have backup situation with a longer headway and what is the capacity of the backup situation and what is it like running in this backup situation? Also, most projects fail...will your headway design fail and what is the backup to ensure you have adequate capacity and should you expect it to fail?)
People know how to build metros with CBTC technology where there is segregation and known operating environments. No one is daring to be creative for shorter headways for lrt with at grade crossings. It can be done. Jerusalem is an example...I don't know how Alstom did it or how much traffic they have to deal with, but they have three minute headways and maybe most importantly Jerusalem transit authorities used a knowledgeable vendor (Alstom) where the vendor was operating in a "good environment". In this case the environment could have been the fact that Alstrom was also implementing the traffic signal priority and the traffic saturation was known and the light rail vehicles were new and the equipment was supplied by ...
https://www.railway-technology.com/projects/jerusalem/
“In common with other modern Alstom networks, the control centre is an integral part of the depot facility from where the route and vehicles will be monitored. Trams are driven under line of sight principles, with built-in priority at road intersections.”
“The line’s impressive 95% availability, 98-99% punctuality, and zero operations-related accident”
“proposing to double the size of the existing fleet to serve the expected 250,000 daily passenger”
In Canada, we use Thales for a lot of CBTC signalling (including our very first skytrain built in the 80's and our latest skytrain extension, as we were the world's first CBTC signalling project implemented by home grown Thales Toronto talent), but Thales has never done an at-grade CBTC system using older light rail vehicles and were fired by the city of Edmonton for never delivering the capacity promised (as reduced headways) and in fact delivering a renovated system with much reduced capacity due to failures in signalling (It is mentioned that there are millions of lines of code for a CBTC solution). So maybe the risk of at-grade is the planning of the project itself in how to deal with the risk of "capacity" failure.
https://edmontonjournal.com/news/local-news/thales-official-...
Thales was fired by the city of Edmonton, and Alstom was hired to put in "old" fixed block signalling so 5 minute headways could work:
https://edmontonjournal.com/news/local-n...seven-months-after-termination-of-thales
I think the major risk is to the headway regularity implementation? To understand whether lrt at grade should be pursued, one should understand if there is any mitigation to not achieving the designed headway (instead of saying that capacity is impossible like it appears to me we are doing in Jan 2019 UBC Rail Rapid Transit Study). Mitigations imaginable (maybe not practical): Imagining all possible failures and planning for them (looking for failures/limitations), running a longer train than initally planned, running in crush capacity (for how long during the day), diverting traffic, allow for testing in non-peak hours in production, allow for capacity slack on day 1 to allow for time to fix code issues (plan an easy implementating day 1 headway with looks to improve it over time), choosing the right vendor, choosing a (mix of) vendor(s) who has implemented an at grade solution with short headways, talking to other operational teams with short headways at grade and seeing the environment they operate in and the failures that are occurring, finding a similar capacity solution and really understanding each vendors capabilities in the solution etc, having backup signalling with backup capacity that is done first.
If day 1 requires a headway that is too small, it may be cause for concern.
Also.any thoughts on what is too long for at grade lrt running in ROW? The TCQSOM - third edition mentions that when running at grade you typically start running the entire block length. There must be some safety or other practical considerations when the block length is 100m or more. Usually it is fully segregated where train lengths can get quite long. It's really a question of practical headway running because if you can get a fully automated system down to 60 seconds you can have shorter trains than if all you can achieve is 90 seconds etc..and this may come down to the system you are using in the field and all it's practical limitations that I wouldn't know about (length of train is one of them, voltage is another, braking etc). But when you come to at-grade..you may have other considerations as well which rule out running over certain sizes. I'm just not sure what they would be. But as a back-up..you need this ability to add trains, so what is the risk of running a longer train? At 150m or so, it may take too long to clear the intersection (I suspect the limitation is 10 seconds of signal priority @ 25km/h so 70m may be a practical limitation).
So not sure if you have some feedback on size of train limitations when running at grade other than traffic signal priority length of time. Can I run a 100m long train. It is certainly less risky for capacity issues..when I can just have the flexibility of LRT and just add a unit to the end..instead of reducing headways on a busy corridor when I have already reduced the headways and ran into some side effects and need to do more testing. Running at longer lengths will impact traffic operations more and this risk needs to be understood better, but it depends entirely on the amount of traffic.
The other question I would have is what about the 4 square meters vs 6 square meters. Is that all just psychological? I think that if a person always shows up at 8:30 and realizes that it will be 4 trains before they can get on..they may push there way to a 6 square meters capacity situation. Is this "crush" capacity worth considering for a 15 minute cram time in the morning for students mostly? I certainly think it is worth considering for a back-up situation in case your initial planning for headways is a little off until you can fix it in due time.
I also think that for an lrt at grade situation, the main risk is underestimating how complicated and how much expertise is required in getting to your minimum headway. It seems anything below 5 minutes and it gets complicated. There is risk. However there may also be a reward in reduced costs, high paying service jobs and better institutional knowledge.
Budapest has done it with L4 and L6 with one minute headways at grade. They would be interesting to talk to see what is going on as well. It appears they did it without advanced signalling.
Eglinton crosstown lrt has a planned 3 minute headway and is a greenfield project. It is delayed, but I wonder what has been their experience so far with trying to implement the 3 minute headway at grade with CBTC. Delay is a risk and that should be understood as well. What's the backup a longer train at higher headways?
Eglinton crosstown LRT (3 minutes planned)
“CBTC – GoA2 - GoA4 • Yard: UTO • Tunnel: ATO • Semi Exclusive: ATP • Headway: – 2 minute Exclusive ROW – 3 minute Semi Exclusive”
http://onlinepubs.trb.org/onlinepubs/Conferences/2019/LRT/YousefKimiagar.pdf
More on Jerusalem's lrt at grade solution with 3 minute headways
“Travel over the complete Red line is due to take 42 minutes from Pisgat Ze'ev at one end to Mount Herzl at the other (as of August 2012, the travel time is 46 minutes[19]). The line operates Sunday through Thursday, from 5:30 am to 11:30 pm, on Friday up to an hour before sundown and not during the Shabbat or Jewish holidays, resuming half an hour after Shabbat or the Holiday ends.[25] Commencing August 2, 2015, frequency will be every 3 minutes during rush hours and every 6 minutes in the daytime and at night. It is expected to carry up to 23,000 passengers an hour during peak morning rush hours.[32] “
https://en.wikipedia.org/wiki/Jerusalem_Light_Rail
At start of operation:
http://onlinepubs.trb.org/onlinepubs/circulars/ec058/ec058.pdf
Design parameters: Initial estimates.
“Traffic signalization and arrangements at 99 intersections will be adjusted and linked to a central system in order to give priority to approaching LRT vehicles. “
“ A fleet of 23 trains, consisting of three LRVs each, will be needed to provide service for about 7,500 passengers in peak sections of the route. These low-floor vehicles will have a capacity of up to 155 passengers each, or up to 465 passengers per train. The concessionaire will have sufficient vehicles to provide base service with headways of 3 to 5 min during the morning peak (and not exceeding the maximum density of passengers per square meter). The peak periods will be 1½ h in the morning and 1½ h in the afternoon. Maximum LRT speed will be 30 kmph (18.5 mph) in the city center and 70 kmph (43.5 mph) on other sections.”
https://www.railwaygazette.com/jerusalem-light-rail-red-line-opens/36208.article
“The line’s impressive 95% availability, 98-99% punctuality, and zero operations-related accident”
“proposing to double the size of the existing fleet to serve the expected 250,000 daily passenger”
https://www.railjournal.com/in_depth/revolutionising-transport-in-the-holy-city
More on Alstom:
http://www.aeamesp.org.br/biblioteca/stm/19smtf130912T22ap.pdf
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