2016-06-27 Mon


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(Calling all Civil Engineers)

Toronto is still one of the few cities in the world where you cannot NOT spot four tower cranes from ANY point in the downtown core (or, for all I know, across the city). This photo is taken from Charles Street Toronto, about a hundred metres west of bay Street. In the construction site are two construction cranes.

I understand that the white crane on the left is sometimes known as a gantry crane. A little trolley runs in and out along the horizontal jib; the trolley carries the hook. The operator rotates the jib around the tower, runs the trolley in or out, and raises or lowers the hook to transfer wooden shuttering, tubs of concrete, bundles of reinforcing bar and so on between the street and the working area. As the building grows upwards, the gantry crane raises itself so that it is always effectively sitting atop the building.

I understand that the blue crane on the left is sometimes known as a luffing crane. The operator rotates the jib around the tower, luffs the jib Ė which is pivoted at one end - and raises or lowers the hook to etc. etc..

Both the gantry crane and the luffing crane work on the same site (presumably TWO condominium towers instead of the usual one).

Both the gantry crane and the luffing crane deal with shuttering, concrete, re-bar etc. etc.

To all purposes and intent, the different types of crane do the same job in the same space.

I learned two days ago that there are TWO reasons why, in Toronto, we sometimes see a luffing crane in operation and we sometimes see a gantry crane in operation.

On my street it was a gantry crane on the first building, and is a luffing crane on the adjacent building, adjacent to Yonge Street.

Lest you think the different types are relative to proximity to a busy street, Toronto would prove you wrong Ė we see both gantry and luffing jibs hanging over all the streets.

There are, it turns out, two reasons why a luffing crane might be on a job site rather than a gantry crane:-

(1)†If the crane tower is too close to an existing building, gantry cranes are prohibited because they might strike the adjacent building. They are, after all, a fixed and maximum-radius device.

(2)†Iíll give the second reason next time I log on, but a clue is already given in this post!

The Toronto Transit Commission

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There is much that I do not understand about the world.

In particular my training in Civil Engineering is non-existent.

My High School education was good; I was taught, and guided into knowing, that in most cases what I didnít know, I could work out for myself from basic principles.

What do I know about Transit?

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The answer to that question is ďI know that I use itĒ or ĎI know that I depend on itĒ.

As do thousands of people in Toronto.

What I canít work out here is why the entire stretch of dedicated (!) streetcar line must be shut down.

I can see that modifying platforms can be tricky. I can see that working on a streetcar stop will involve workers standing around in the middle of the right-of-way. I can understand that heavy equipment (such as back-hoes and so on) might need to be called in to do the heavy lifting.

What I canít work out here is why the entire stretch of dedicated (!) streetcar line must be shut down.

I have this memory of riding a subway train which travels slowly along a section of track on which work is being done; workers flatten themselves against the wall while the train passes slowly, then the workers resume, well, work.

There is a man with a flashlight; there are orange stud lights; there are yellow flags. I am CERTAIN that there are honking big signs awaiting the train operators when they report for work.

Why canít we have the same sort of operation above ground?

In Particular, why canít we have a team of workers shut down ONE streetcar stop while they work on it and have the streetcar just skip that stop for a week? That would be an inconvenience, possibly even an annoyance, to a few riders (although the automated voice system could warn passengers, and the driver could announce it as passengers boarded)

Wouldnít it make more sense to work on the streetcar stops one (possibly three) at a time? A disruption in service at one stop is not a big deal, as long as the line continues to run and all the other stops are serviced.

The back-hoes could be brought in at night time when the streetcars are not running, or could be operated outside of peak hours.