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For some reason, the Pattullo Bridge reminds me of this.............. Spoiler! |
just went over the bridge today. wow it's rough... it's rough concrete with no ashpalt on top, so it's a bumpy ride. if you are on an aftermarket suspension... enjoy. |
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1. Trains weigh a fuck of a lot. 2. Trains can't climb inclines and declines like cars. 3. There are MAJOR engineering and structural ramifications to building a combined bridge. 4. Incidents by either the road using portion, or train moving portion could leave the other portion unusable. 5. What about pedestrian and bicycle traffic - you have to be conscious of their safety as well. So: 1. Because of the weight of a train, train bridges require a lot more intermediate supports than a regular car or pedestrian bridge. Which means that might restrict the size of the boats trying to get into the channel. It also means that you want to the bridge as low as possible (without interfering with boat traffic), because you don't want to build 15 supports which are 100m high instead of 15 supports which are 20m high. 2. Because train's don't deal with large slopes very well, rail bridges are often built as level to the tracks on either side as possible. I'm sure you've noticed how many rail bridges are either the dual active style (lifting) or Bi-Directional (rotating) to allow taller ships to get through. This isn't because they like fancy engineering, it's because that's a cheaper option than building a tracks at a 3 degree slope for 10 miles in each direction to make up the height to get the trains up to the height at which the Patullo operates. There's a lot of other considerations as well, but lets just leave it at this; particular location, a long with literally 98% of other train crossings will never be mixed with general road use. There is actually under 100 combined bridges in the entire world. You can see an entire list here: https://en.wikipedia.org/wiki/List_o...93rail_bridges |
a bit of trivia... the burrard street bridge was designed to be a 2-level bridge with cars on top and trains down below, which is why it looks like it does... but the train part was never done :eek: |
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I guess had they done that though, the lower decks today could have been converted to pedestrian and cyclists. Instead of the ongoing 20 year battle we have seen between what to do with that bridge (and the 10 years of construction it's been under while they try to decide). |
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They had planned for this opening, as back to school traffic would be a shit show with the current bridge situations. If they promised this date and missed it, the lynch mob would be out of Translink's head. Now they look like rockstars for delivering a month early, which isn't really the case. |
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When a project first goes through feasibility they figure out a base schedule, and a base budget. This budget and schedule are based on the very bare metrics. AKA the plant produces 45 megawatts, other 45 megawatt facilities costed 100 mil when they were completed and took 2 years. Or the facility is 60 tons per day, other 60 TPD facilities costed 500 million and took 1.5 years to complete. They then take that budget and schedule to the owners, and the owners ask for them to try and bring the number down, so they pull their tricks, and lower the numbers 10%. The owners then take that number and go to their financiers and present it, and over and over the financiers say no. So the owners continue to go back to the engineers and planners until they beat the number down another 20%, then the financiers finally green light the project for engineering. Now finally detailed engineering can start. The engineers make a series of recommendations some of which the owners opt for, which may be slightly out of their budget. So eventually when the package is complete and the project goes out to tender for suppliers and contractors, the bids come back much higher than the budget and schedule allow. So the owners come back and ask for value engineering, they manage to bring the numbers down 10%, thats not enough, so the owner takes risk off the contractors, and removes the liquidated damages clause and the pulls all the money they can out of every nook and cranny to move forward on the project. Now they have no contingency money, no backup plan, and their schedule is compressed as if it had been put through a trash compacter. Of course they fucking fail, there was no shot in hell from the beginning of the project. Then they all cry, and a bunch of people lose their jobs when the project ends up being exactly where the bare metrics told them it would be 2 years earlier. The project is then added to all the historical data, and 2 years later when the owners go to another project they are doomed to repeat all the same mistakes, because nobody ever learns anything from the fucking lessons learned that I make for these projects. |
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