According to legend, every March the swallows return to San Juan Capistrano. Because I grew up in LA and spent my summers in San Diego, I endured countless drives through Capistrano, which lies midway between the two. And each time, I though about San Juan Capistrano’s claim to fame: the swallows. We here in Redwood City may not have swallows, but these days we have cranes. Not the avian kind, though, but the construction kind. Pretty much anywhere you look in downtown these days, you can see a construction crane rising into the sky. A veritable flock of construction cranes, as it were.

Crossing 900 is the most visible contributor to our current crane population, given both its location right in the heart of the theater district and the fact that its construction requires two large tower cranes:

These two cranes are in near constant motion at the moment, and will be for some time as the steel framing on these buildings continue. The structural steel framing is due to be complete in mid-August; I’ll be curious to see how long the cranes remain after that. Presumably they will be used to lift other heavy items to the building roofs, and perhaps they’ll lift building materials to the building’s upper floors as well. But due to the cost of renting one of these things, I’m sure that the developers (Kilroy Realty and Hunter/Storm Properties) will return the cranes to the Bigge Crane and Rigging Co (from whom they rented them) just as soon as they can.

Tower cranes are very expensive, and only used in large projects like Crossing 900 where their cost is only a small fraction of the overall cost of construction. A typical cost to install and later remove a tower crane is around $60,000. Add to that a typical rental price of $15,000 per month, plus the cost to sink the needed foundation, and you can see that these things can get pretty expensive.

When you need one, however, nothing else will do. By itself a tower crane can rise to around 265 feet. Need to go higher? No problem: you just anchor it to the building under construction. The working arm—the part that extends out from the tower along which the load-carrying trolley runs—can be as long as 230 feet. And the maximum load that one of these things can lift is 18 metric tons (but only if the trolley is close to the mast; at the tip of the working arm the crane’s lifting ability is significantly lessened).

To keep the crane from falling over, it is bolted to a large concrete pad. Typically this pad is around 10 by 10 feet, and four feet thick. In total, the typical tower crane pad weighs some 400,000 pounds. Then, up to 20 tons of counterweights are placed on the back of the working arm to counteract the weight of the working arm and the load it is carrying.

I had the good fortune to visit the construction site of 601 Main Street the other day and see their crane only partially assembled. The mast was up, along with the cab where the operator rides, but the working arm was yet to be installed:

In the above photo, the yellow tower in the center of the image is the partially assembled tower crane. The black-and-white crane on the left is the mobile crane that was being used to assemble the tower crane. The sections that make up the tower crane’s working arm are not visible; at the time I took this picture they were lying near the base of the crane, in the hole excavated for the project’s underground parking.

Here is a closer shot of the top of the tower, showing the operator’s cab and the point where the working arm will be attached to the tower:

Within two days, the crane was fully assembled. Unfortunately, I wasn’t around to see them hoist the working arm segments and put them together. But I did take this shot of the finished crane from the top of the Marshall Street parking garage:

601 Main will eventually be an eight-story building (with two levels of underground parking); the tower crane will be needed to raise and help assemble the project’s steel skeleton. Once the crane is no longer needed, it will be disassembled and hauled off to its next job.

Nearby (at 525 Middlefield) excavation is well underway for the Indigo project. This one will be the  largest of the current residential projects: three 10-story towers containing a total of 471 apartments. Although their cranes have yet to arrive (and a project this size is likely to require more than one), I believe that the large square hole at the center of the following photo is probably for the base of a crane. Given that this hole is at one end (near Bradford St.) of a long rectangular-ish project, I would guess that there will be a second crane located at the other end of the property near Veteran’s Blvd. But that end of the property is still being worked over by tractors and bulldozers, so we’ll have to wait to have that guess confirmed.

Not all of Redwood City’s construction projects require tower cranes, of course. The Maple Street Correctional Center, for instance, is using a mobile crane during its construction:

Here, the workers were done for the day: they seem to put the crane into a “resting” position when it isn’t actively needed.

The 24-Hour Fitness being built just past the main post office on Broadway and Woodside is also using a mobile crane at the moment, but a much smaller one for a very specialized task: pile driving.

I just can’t believe how slowly this particular project is progressing! I first reported on this project nearly 11 months ago, in my post Broadway Bound. Since they were actively moving dirt around at that time, work probably commenced almost exactly one year ago today. And what do we have to show for a year’s worth of construction? A well-defined but unpaved parking lot, a “24-Hour Fitness” sign, and some pilings for the building’s foundation. Back then I figured that it might take about a year for this club to open. Hopefully no one was planning to join this particular gym this year! It’ll be well into 2015 before the doors open on this one…

Tall steel buildings seem to require a tower crane (or two). Smaller building projects use a mobile crane for some jobs, but can do much of the needed lifting by employing a simpler, cheaper device: a construction elevator. “Elan Redwood City,” for instance is mostly wood-framed and thus is using an elevator temporarily bolted to the side of the building under construction to lift the framing, plywood, plumbing, and other building materials to the necessary heights.

201 Marshall, now complete, also employed a construction elevator during the building process. In the following photo [click it to see a larger photo] the framework along which the elevator cab rides is a little hard to see, since it extends no higher than the top floor of the building. But the grey elevator cab can just be seen behind the green construction fence just to the left of the orange “Road Work Ahead” sign. And the red safety doors on the upper parking level and the first residential level are pretty easy to spot.

Of course, some items are too large to be carried in an elevator. And you do have to get the elevator itself installed. Thus, you will still need a mobile crane for some parts of the job. 201 Marshall was no exception. Earlier in its construction I took this photo, showing a pair of mobile cranes that may well have been installing the construction elevator:

There is more than one way to skin a cat (as the old saying goes; sorry to all you cat lovers!). While building 201 Marshall I was fascinated to see that the contractor also employed a simpler form of elevator to whisk drywall, framing, and the like up a couple of stories:

This thing is basically just a long ladder along which a carriage rides. A cable extends from the carriage up to a pulley on the top rung, and then back down to the bottom where the motor is located. The operator, standing on the ground, can thus send a load up to a higher floor where it is needed. I watched many a load being raised to the building’s fourth floor using this mechanism.

Elevators may make a great deal of sense, and of course they are very likely much cheaper than a construction crane, but ask any kid and they’ll tell you that cranes—in particular, tower cranes—are much cooler. Elevators blend in, while cranes stand out and catch your eye. Take a casual glance around Redwood City these days: you’ll see a lot of them. Like swallows, they come to our city, stay for a while, and then move on. Unlike swallows, however, only if additional large construction projects break ground in our city will they return; construction cranes most certainly don’t engage in an annual migration like Capistrano’s swallows!

Still, while San Juan Capistrano has its swallows, for now we have our cranes. And they are changing our city in ways that swallows never could. Lets keep our fingers crossed that those changes truly are for the better.