Large bridges can be relocated using a sliding mechanism with rails and PTFE (Teflon) surfaces that reduce friction, allowing hydraulic jacks to incrementally push the bridge 3 feet at a time over 24-30 hours; this technique enables bridge replacement with minimal traffic disruption, as demonstrated by the 19 million-pound Commercial Street Bridge project where the new bridge was built completely offline and then slid 102 feet into position after the old bridge was demolished.
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Deep Dive
How do you move a 19 million pound bridge?Added:
Hey, Boaz here with Next Pittsburgh.
Yes, I've got the hard hat. I've got the very bright vest on, which means we are on an active construction site. Behind me is the Commercial Street Bridge, both the old and the new one. We're going behind the scenes. I'm here with Jason, who's a district executive at PennDOT for District 11. And this is a pretty big project. I imagine one of the bigger projects you're working on right now.
Yes, this would be the biggest, I would say. This is the biggest, most important and critical project we have going on in District 11, yeah. It is really We're in the thick of it right now. There are tons I don't even know how many construction folks working around us with various vehicles. And And above us is you know, the current bridge that that's still currently in use.
Um and then right next to it is is the new bridge. And And this is Is this the normal way to build a bridge or this is sort of a fancy way to do it?
This is a a fancy way of doing it doing it, but out of necessity.
>> Yeah. Yeah. And so, how old is this bridge? Do you know?
This bridge was built in the early '50s, 1950. So, it's approaching 80 years old, 75-80 years old. And And looking around, you can see like you've done various repairs over the years, but now it's time for a whole new structure. Oh, yeah. We've made repairs to it, but it's really at the end of its useful life. It just needs to be replaced. We can't repair it. We can't strengthen it in a feasible manner. So, we've got to replace it. So, over here, this is like solid steel over here. There's no, you know, concrete over there. The new bridge is a steel uh superstructure. Um and we we went through the various ways uh in the various studies to look at what kind of bridge should we build. The The Parkway East is is a historic corridor.
Um and there was historic aspects that we had to consider. So, we did want to put back something that kind of mimic the original bridge. So, I mean, the original bridge was a beautiful structure. It still is. It's a little beat up and and worn out, but it was a beautiful like kind of Art Deco treatments and everything at the time.
So, we did want to kind of show respect to that and put something back that that gave a that the arch look. Although, this is not technically an arch, but it gives the arch that arch look.
>> And so, you've built this little frame presumably to protect things cuz I'm sure sometimes there's, you know, you're shooting sparks up there when you're welding things or whatever.
>> Or somebody drops a wrench or or whatever. I mean, yeah, things happen on a construction site. So, this is to protect the trail users and we're able to keep the trail open, which is good.
Um nowadays when you see a house being built, you don't see them framing the walls. The the walls come out on a truck and they put it together. And that's kind of what we're doing here is we're doing everything we possibly can before we get in the way of everybody on the road.
So, lay it out for us. We've got the old bridge, you've got the new bridge, and you're building the new bridge on some sort of movable track. So, we're building a complete bridge offline. 100% complete bridge. So, the plan is close the road July 10th right now.
We remove the old bridge. So, what we'll do is we'll we will we will slice up the the concrete deck. That's the roadway surface. We'll cut that up into pieces.
We'll knock it down down onto the ground in this case. Sometimes we pick them up, but then in this case we're going to knock it down. And the only thing that'll be left are the arches and the vertical columns. And then we're going to blow that up because that's fast.
>> Yeah. And that's safe. Believe it or not, it's safe cuz it's Cuz you know exactly how much explosive to use. It's not like you're you're doing something crazy.
>> There's experts for that, but it's much safer to bring it down onto the ground and get rid of it than have people climbing around unnecessarily taking things apart. So, knock that down. Once we do that, we start to slide the new bridge into place. We have to put the There's what's called abutments, the end supports. What is actually happening when you're sliding that bridge over?
And how many I don't even know. Does it have to go over 100 ft or something? I mean, it doesn't have to go over that far. 102 ft to be exact.
>> Wow, I'm close. I thought that's a good guess. Yeah, so it's it's roughly 20 ft away from the old bridge, but but the new bridge is wider than the old bridge, so so the whole mass itself moves 102 ft, right? Like how? Like how do you build a train track? Like what's going on?
Kind of. It's It's It's a rail. Um it's almost like an upside down T.
It's a proprietary type system. So a rail goes down and then uh they they layer it they put a a layer of PTFE, like a Teflon plastic surface, okay? That'll have these these these apparatuses that that can jack the bridge up, lift the bridge, and then slide it. So it'll lift it and then it'll slide. Almost like you ever think of those um those plastic things you put underneath like a table leg and you could slide the table around your carpet? That's all we're doing. That's That's literally what we're doing, but just on a much heavier scale. Uh and it has hydraulics that will push it, and it can push it 3 ft at a time, reset itself, 3 ft at a time, and just keep just keep pushing it over. It's going to be very slow. It's going to be like watching paint dry.
But >> How long does it take to move a bridge 102 ft? It'll take about 24 to 30 hours is what we anticipate to slide the bridge into the into the permanent location. And so what's happening behind us right now? People are on a little sort of cherry picker rig and they're doing something.
Yeah, so there's multiple things happening on the site at one time.
There's people up top um putting down what we call deck pans, and that that's what holds the wet concrete before it cures. So those are metal pans that stay in place. On top of those are the rebar mat will go down. So bridge decks have a lot of Oh, any structure has a lot of reinforcing steel in it. That's how it gets its str- its strength, so that will That's happening right now. They're assembling those mats and getting the steel ready. Uh the the people you see right now, they're tightening all the bolts on the bridge.
>> Like you just look at each of those panels and they're just like I don't even know like 50 bolts on each of those. Like there must be thousands and thousands of bolts on this bridge.
>> Yeah, I don't know the number off hand.
But I mean you got to get it here, right? So it comes in pieces, pieces that are manageable that you can put onto a truck and haul. And this bridge came from Wisconsin. That's >> So do you know how many pieces the bridge comes in? Yeah, for this bridge it was 140 different deliveries to bring all the pieces in and then assemble them down here on site. They come partially assembled but they mostly putting it all together down here. But they all It's like a crazy IKEA thing. You look, okay, do you have an A7 anywhere? I need a bolt an A7 onto this part now.
>> That's exactly how they do it. They're all numbered. Someone's following a plan and putting it together. That's really how it works. Yeah. And so during that 30 hours where they're inching this bridge into place, like are you going to be here like sort of biting your nails? Like I hope this all goes okay. I'll probably be pulling hair out of my head and and watching the traffic and just completely, yeah, worried about it. It'll be It's not going to be a comfortable three three weeks for me or anybody at PennDOT for that matter. So, yeah, of course it's going to be nerve-racking. I mean I have all the confidence in the team. They're going to pull it off. It's going to be great.
It's going to be a new bridge in three weeks. And these are some of the most creative and innovative people you ever meet like contractors are really and designers and engineers. I mean very innovative and creative and you have to be to get this done. I mean this is amazing.
And so this will only require you to close the bridge for for under a month?
Right, 25 days. Yeah, and um we have gone out on a like probably the the largest public outreach campaign I've I've ever seen in my career for this. And we've done some big projects but we've never closed this Parkway. At least in my career I can tell you we We closed this Parkway for this kind of duration. We closed it a week years ago to demo a bridge, the Greenfield bridge.
So, this is the longest we've ever closed it. We want to make sure everybody knows. Yeah. And we're we want everybody to plan ahead. Right. Now, we know it's going to be miserable, probably, right? It's I I can't I don't know how it won't be. It I think people will get used to it and find ways around. It'll get better. But, the thing to keep in mind is we've been working on this bridge now for 2 years.
>> Yeah. And we hit essentially have really not impacted anybody. I mean, we're out here and building this massive bridge.
When you do things in pieces, you're going to close it a week here, then you're going to close it a week here, and everyone's going, "Wait, when were they closing it again? Well, they just opened it. When are they going to close it again?" So, to me, this is clear.
It's clean. It's not going to be fun.
So, hopefully, that 3 weeks goes by quickly, and we have a new bridge here for the next 100 years. And you were mentioning you you chose July carefully because it is one of the sort of the lowest traffic months of the year here.
Yeah, that's right. So, like most of the time in our projects, we don't we don't tell a contractor exactly they have to do something. We say, "Look, you have this many days to get it done, and you have to avoid this, and you have to avoid this, the Great Race, and you have to avoid the marathon, or whatever, or Light Up Night." But, in this particular case, we put it right in the contract documents that the closure has to occur in July, around July 10th. And and that's because that's when then the traffic volumes are actually at the lowest. People are off summer vacations and doing whatever. School is out.
That's a big one. Well, Jason, thank you so much for this really fascinating tour, and I'm excited to see sort of how the rest of this bridge take shape.
Yeah, I appreciate you coming out and your interest, and we really um we're doing everything we can to spread the word. You're helping us, so we thank you for that. Um we would we would ask everybody, please visit our website. Um if you just Google Commercial Street Bridge Project, it'll be the first thing that pops up. There's a lot of information there. There's maps. There's detour routes, and suggested uh information. So, do that. And also, just just I want to thank the public in advance.
We got to get through this together.
It's going to take all of us.
We'll get through it. We'll survive it.
And And when we're done, we're going to have a beautiful new bridge that's going to be here to serve serve everybody for the generations to come. So, appreciate everybody's patience.
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