Building in highly dense city centres presents a unique set of challenges—tight spaces, heavy traffic, and the need to preserve historical structures while meeting modern safety and sustainability standards. 

Today, we hear from an experienced engineer turned project manager who is an expert in navigating these complex logistics, from coordinating material deliveries with precision to ensuring that construction doesn’t disrupt the surrounding urban landscape. We hear how to safely excavate deep beneath a centuries-old building and what it takes to integrate modern engineering solutions into historic sites, along with the ever-growing importance of sustainability in engineering.

Our guest today has nearly 30 years of experience in construction across sectors such as pharmaceuticals, semiconductors, and large-scale commercial projects. He is a regional director at PJ Hegarty, John Gavigan. 

THINGS WE SPOKE ABOUT
●    Diverse and challenging projects keep work interesting 
●    Mastering logistics in city-centre construction
●    Blending modern engineering with historic structures
●    Making safety the number one priority of any build 
●    The evolving role of sustainability in construction

GUEST DETAILS
John Gavigan joined PJ Hegarty in 1996 as a graduate engineer. He progressed within the company, embracing new responsibilities and roles, completed several projects as Contracts Manager and was appointed as Regional Director in 2023. John’s experience includes projects across several sectors: pharmaceutical, city centre commercial, healthcare, semi-conductor, logistics, education, retail and PPP bids. He was the site lead for 10 Molesworth Street and Tropical Fruit Warehouse in Dublin city centre and the Zoetis project in Tullamore.

Engineers Journal AMPLIFIED is produced by DustPod.io for Engineers Ireland.

QUOTES
"The challenges are the things that you remember. That's what keeps it interesting." - John Gavigan

"Getting concrete trucks into the city centre location in the middle of the day during business hours was very challenging." - John Gavigan

"It's knowing how to judge when there's an opportunity." - John Gavigan

"As an engineer who has evolved as a project manager in my career, you learn different problem solving techniques, you develop analytical skills." - John Gavigan

KEYWORDS
#Engineering #City #ProjectManagement #Construction #Logistics #TrafficManagement #Safety

TRANSCRIPTION
For your convenience, we include an automated AI transcription:

Dusty Rhodes  00:01
Building in highly dense city sites is not easy. 

John Gavigan  00:06
Getting concrete trucks into the city centre location in the middle of the day during business hours, was very challenging. We used Stevens green as a holding area in consultation with the guard E for our concrete trucks.

Dusty Rhodes  00:20
Hello, my name is Dusty Rhodes, and welcome to AMPLIFIED: the Engineers Journal podcast. Today, we're discovering some of the challenges of working in highly dense areas, usually in highly crowded city centres. Our guest has quite some experience in this area since joining PJ Hegarty as a graduate in 1996 he's worked across several sectors, from pharmaceutical to semiconductor and city centre, commercial to retail and PPP bids as well. It's a pleasure to welcome to the show. PJ Hegarty, Regional Director, John Gavigan. How are you, John? 

John Gavigan  00:51
I'm good. Good afternoon Dusty, glad to be here.

Dusty Rhodes  00:58
I always start by asking people what sparked your interest into getting into engineering?

John Gavigan  01:05
Well, I grew up on a farm, and there was always a little bit of concrete to be mixed, be it for a standing a gate post or doing bits and pieces of repair work around the place. So there was a natural kind of progression. I liked studying the science subjects and mathematics at school, and kind of indicated, from my chat with my career guidance teacher that engineering might be a good route. And ended up studying engineering and getting a job in the construction side of the industry, and kept going for nearly 30 years now.

Dusty Rhodes  01:39
It sounds like you were kind of like you just fell into it by accident. No huge draw for it, but you are still in the business 30 years later. So what, what do you find fulfilling about the work?

John Gavigan  01:51
Yes, that would, that would be fair. It wasn't something that I wanted to do, and was clear in my in my destination from from a young, young age. But since working with PJ equity, I found that there are a wide range of diverse projects out there, and every project is different in so far as every project will have its own specific challenges, and the challenges are the things that you remember. You know, one reinforced concrete frame building or one steel frame building might be the same as the next post. The nuances that you remember that keep that keeps it interesting. It's been, it's been said to me that to be, to be a good project manager, you have to have knowledge that's a mile wide and an inch deep. So it's fairly diverse, that the scope of knowledge that you have to have things from, like I said, concrete and steel and pure engineering, right down to the to the finishing of a job, ceiling tiles, ceiling finishes, tiles, carpets, all of that type of stuff. So it's fairly broad.

Dusty Rhodes  02:52
So you say a lot of jobs are, I would don't want to say standard, but you're able to handle kind of most of the work. But there are occasional jobs that are extra challenging. Any any particular ones that pop into mind?

John Gavigan  03:04
Yeah, I mean, I remember the downturn in kind of 2009/2010 there was much work going on in 2010 for the following years afterwards, and we won a project on Molesworth Street. It was the old passport office, and the job entailed demolition of the existing structure and deepening the basement. It was already a two-story basement. There, we had to construct a third story, all of which had to be done in a live city center setting, immediately adjacent to a Georgian building built in the 1700s and we had to excavate, you know, 11 meters below that, unaware of what footings were built in the 1700s and we had to make sure that everything was carried out safely.

Dusty Rhodes  03:52
Obviously, I know the building, you mean, on 10 Molesworth Street, because I remember, got my first passport from there. But what kind of rules and regulations and planning and everything do you have to go through when you are building a modern building, besides something that's 200 years old.

John Gavigan  04:07
The standard way of ensuring that you can excavate a basement safely is to install a secant pile wall around the full perimeter, which basically means you're coring. You're coring down with a large, 70 ton machine and placing a column of concrete 10, 12, 14, meters, and you're reinforcing every second pile with a reinforcing steel cage to give it the strength to withstand the pressure of the soil and the traffic driving by in the adjacent the adjacent street, so that allows you to excavate without the risk of either the soil collapsing in a top or, in the case of the Georgian building, the Georgian building been undermined and and settling and cracking and having failure start now where, where you have buildings immediately adjacent to an excavation for a basement, you would carry out an. For level of assessment, we engaged a specialist design engineer with experience in temporary works design like this. So in addition to the second pile wall, we put in a considerable amount of extra thought and effort and concrete underpinning and also raking, raking steel anchors, which are basically steel steel rods drilled in at typically 45 degrees and grouted in place with a like a weak concrete mix of cementitious grout to give extra hold and extra strength to the ground and to ensure that there's no no slippage. And obviously, you can imagine a 1700s building if there's any sort of movement at all, you're potentially going to get serious cracks or even more catastrophic failure.

Dusty Rhodes  05:47
Now, somebody came up with the design creative for the building and the plans for that, and then when you eventually arrive on site and you see all of these problems that you have to solve, did that change the initial design at all subtly.

John Gavigan  06:02
Yes, typically, we inherited design and and we build it, but we do advise on on ways to improve the project for all parties involved. And if there, if there is a way that the design can be subtly, subtly changed to make it easier or better, then we do that. I mean, there was, there was a quite a large concrete slab in the in the basement. Getting concrete trucks into the city center, location in the middle of the day during business hours, was very challenging. It was designed with, you know, several slab bores in mind, because typically the size, the size of the slab, is determined by how quickly you can get the concrete deliveries to the site. So we discussed with the consultant about increasing the slab pore sizes. The reinforcing was amended to suit and we had with bigger pores. As it happens, we and we chose to do them at night time. So we used Stevens green as a holding area in consultation with the guard E for our concrete trucks. We brought them down with traffic marshals as needed, and we hit, you know, three, three stations set up to pump the concrete from around the perimeter of Molesworth Street, Setanta place and Frederick Street, for anyone that knows the area. So we had three, three angles of attack, whereas that just wouldn't be possible during business hours.

Dusty Rhodes  07:25
It sounds like an organizational nightmare. Was it okay dealing with various authorities to be able to close off streets and to get the trucks in?

John Gavigan  07:33
Yes, um, Dublin City Council or the local authority, and any work outside of ours had to be, had to be done with their approval. Permits were generally issued, and it was a requirement that we consulted with neighbors. We did have a good relationship with with the neighbors. We engaged with them from very early on in that project. In fact, I can remember the very first Christmas that we were there, myself and two of my colleagues, and we spent two afternoons knocking on doors and shaking hands and actually meeting people. We handed over our contact information, and I have to say, you know, we didn't get any spurious complaints. We did get a number of inquiries over the course of the project. The project was three, three years. We made some good friends. We got to know a few people we didn't always have the the answer or the explanation that the neighbors wanted, but I think they always understood, and we certainly had. We left, we left there with no complaints. And it worked. Worked very well. The local authority wouldn't tend to issue permits for subsequent out-of-hours work if you didn't comply with their conditions for the early ones. So that worked very well.

Dusty Rhodes  08:42
There's an awful lot of development going down, or there has been the last, certainly, 10/15, years in the Dawson Street area. I know that developing the corner of Dawson Street, just at Trinity College, the bottom of Dawson Street, from your experience, when you are literally in the beating heart of the city center. What are the biggest challenges in the project for you, working in that dense area?

John Gavigan  09:07
It's the logistics of getting material in and out. Most of the workforce are accustomed to starting early, so it's not unusual to have 100 guys at the site for 7am, the key to servicing the project is getting deliveries in early ahead, ahead of the traffic. So they would often be in, especially if they're coming from overseas, or particularly challenging logistic deliveries that would be that required the big the big trucks, the big Arctic, 13-metre trucks, or even longer, if there are specialist items that has to be brought in and brought in early. If there's any any traffic movement, it has to be managed with traffic marshes at the periphery of the site. Any interaction with pedestrians or public traffic really has has to be managed by, typically two or three specialists, trained traffic marshals. So the experience of those guys is. Is really what we rely on. It's knowing how to judge when there's an opportunity. It's professionally designed by a traffic management consultant, and the plan and the vehicle movements will all be tracked with with software to verify that where we designed for a pull in area will actually work. So there's, there's, there is science behind it, and then the local authority then have to issue their permits for these pull in areas, if they take off, you know, footpath areas or whatever. So it's, it's something that is thought out, that that is, that is the key to it. Building is typically easy. It's as easy to build in a green field site five miles out outside of the city centre as it is in the city centre, but it's getting the material and service, and it is the key.

Dusty Rhodes  10:39
What lesson did you learn from that project that you would apply to future developments?

John Gavigan  10:43
Well, that's an interesting question. The project immediately after that actually was an equally challenging one. Is an office development on the keys, and it was more challenging and so far as it only had one entrance, a narrow entrance immediately off the keys. So while Molesworth Street was very busy on three sides, the three Busy, busy rows were on three sides of it. This one on the keys only had, in fact, one entrance to it. So the logistics challenges and tricks that we had learned on Molesworth Street were useful in the follow-up project immediately afterwards.

Dusty Rhodes  11:21
Are you talking about the tropical fruit warehouse? Are you? That's right too. That's a go. I mean, for people who don't know it, it's a beautiful red brick building, and I believe, from the late 1890s and it kind of contract. What I love about is, when you walk across the Samuel Beckett bridge, you see this beautiful, old red brick building, and then it's just surrounded by modern glass, left, right and center. But getting into that site was particularly hard for you because it was only the one at one entrance. So what did you learn then from Molesworth Street that you were able to apply then with the tropical fruit warehouse?

John Gavigan  11:56
Yeah, it's it's been able to have the same guys that were managing the traffic. One team moved from one job to the next, and it's a matter of making sure that we had the guys that knew, knew how to knew how to deal with it very challenging, and everything had to be scheduled, but to within an inch of its life. You know, it was all look ahead, daily, daily coordination to make sure that deliveries arrived. If deliveries didn't arrive on time in the midst of slap by a few minutes, then unfortunately, they had to. They had to reshape it,

Dusty Rhodes  12:28
from the sounds of it. It's the logistics of getting everything to the site. But once everything is there, construction goes on as usual. I can imagine, with a nice I'm going to call it a simple construction where you have a space and you're pulling up a building, but with the tropical fruit warehouse, you have to keep the original building from the 1890s and build over and around and behind it. That must have presented some unique construction challenges for you.

John Gavigan  12:55
It sure did. I mean, as you've described it there is pretty accurate. So it's an existing two-storey warehouse. It had a slated roof on timber trusses. The original timber trusses were there from the 1800s, typically a 14-metre span or thereabouts. The timber trusses themselves had evidence of a lot of decay at the ends of them. Think 12 of the 30 trusses required significant refurbishment, so the roof was stripped, the slates were all stored and salvaged for reuse, and the timber trusses were taken carefully off-site and sent for refurbishment, where the ends, where there was decay present, were removed. All the joints were tested and refurbished, and a special splice detail at Timber resin splice was installed to replace the bearing ends where the timber had decayed. And that was actually carried out with timber that was salvaged from an old church in Leeds in Yorkshire. So the specialist company that we used use this recycled salvage timber, because modern timber wouldn't have the same engineering properties as fully seasoned timber that had been used in a similar application. So that was the roof, part of it, and once the roof was taken off, we had to construct a six-storey new reinforced concrete core. And that was one of the one of the timber, one of the concrete towers that you'll see poured around typical project in the city center. But what was different then was we constructed a two story steel frame that was basically hanging off this central core. So it's a cantilevered steel structure, you know, four and five floors, plus a plant room on top for the sixth floor. So in order to safely construct a hanging steel frame, we basically had to build it up from the ground. So we built a six story steel structure, but when it was complete, then removed floors, one to one to three. Inclusive below, if that makes sense. So we had to build fill it up to support it, and then when the permanent connections were in place, we controlled the removal of the temporary steel frame underneath it, which was three stories.

Dusty Rhodes  15:16
Did you have the confidence to know that when you removed it, everything was still remain standing?

John Gavigan  15:25
I mean, there was, there was so much attention given to that that there was never any any concern that anything was going to go significantly wrong. But we were obviously concerned that everything went 100% right, as it happened, it did. I mean, there was a whole, whole series of transfer of weight. So if you can imagine that the propping steel, the temporary steel, removed from from the permanent structure, initially, you're going to get a sagging under the self weight of the steel, steel frame when you remove the temporary, temporary support. So it is going to it is going to psych the next stage was we, we poured concrete slabs, and that's going to introduce yet, yet, further settlement, extra weight. And then the not insignificant weight of the glass cladding on the on the facade is going to introduce more weight and more deflection. So at each of those three stages, we measured deflection to verify that the structure was doing what it was supposed to do. The consultants who designed the steel frame had included predicted deflections for each of these stages, and we monitored them in the world within the expected range, thankfully.

Dusty Rhodes  16:41
Do you remember what the deflection was?

John Gavigan  16:44
Yeah, it would have been 25 millimetres, and slightly over that in some, some instances, I mean, there's quite, there's quite a significant distance from the point of support to the to the edge of the structure. The cantilever was 14 meters. I think that's the highest point.

Dusty Rhodes  17:01
Working with the tropical fruit warehouse and with 10 Molesworth Street, you are working with very, very old buildings. Besides, you know, brand new modern constructions. How do modern building codes and regulations work with such old buildings? It's like you were talking with the roof and the struts, and everything do you have to maintain the originals?

John Gavigan  17:22
That's that's a very interesting question, and that's something that we discussed at length at the start of the project, because the and you've actually hit the nail on the head there with the timber trusses. So the timber trusses were whatever 18, 1870s and we know they were fit for purpose, because they've been supporting the roof for the last 100 and whatever it is, well over 100 years. Yet, when we took them off, refurbished them and put them back on, the designer is responsible for certifying that they can withstand the future loads and comply with modern building codes. So in order to do that, initially it was thought, well, there's a lot of iron fittings, wrought iron fittings connecting the various node points of of the timber trusses. Like I said, these timber trusses were over a ton in weight, 14-metre span, you know, eight feet higher there. But lots, lots of interconnecting struts and different timbers, timber sections and compression and tension and lots happening at all the joints, so that the engineer responsible for the design and start to find it wanted to be satisfied that the timber was sound and the metal fittings were sound. So one way of doing that is to dismantle the fittings and the joints, carry out analysis of the timber to check for the presence of rot, and make sure the fibers are all in good condition. The timber is performing well. Carry out X-rays of the metal fittings to make sure there's no micro cracks and future potential for failure. But the specialists advised guys, if we do that, we're likely to damage a lot of the fittings and possibly the timber and the chances of being able to reinstate using the initial materials is is slim. You know, you're looking at potentially more than half, half of the joints having to be redone, which goes against the conservation ethos of the project. And you know, there's other other complications as well, like costing more money, which is often the consideration point. But in order to satisfy ourselves, there was a quite, quite an innovative testing regime set up. None of the none of the people involved in the project had come across it before. It came from a specialist consultant from the UK who was working with the refurbishment contractor that we were using, and when I've gone into it in too much detail, it was a dynamic loading rig was set up, and a sample number of the trusses were put through their courses with loading to mimic the permanent scheme. And all of the trusses that were tested were found to be well. Capable of carrying, of carrying the loads that they'd be subjected to, much better performing than if they were designed for new and modern. Trusses will be designed to perform much more efficiently. There's a lot more redundancy, a lot more spare capacity in these trusses. So there was a lot of effort went into checking and making sure that all the trusses were were performing well, and a good sample of them were load tested, and that got us over the line. So that means that everybody can sleep at night knowing that the structure is performing and will comply with modern building codes.

Dusty Rhodes  20:33
With the tropical fruit warehouse and again, Molesworth Street on the Georgian buildings there. Do you ever sit back and consider the work that some other engineer had done on that site 200 years ago.

John Gavigan  20:48
Yes, I mean that tropical fruit warehouse. When we took possession of the site, there was an old masonry wall that had a significant build-up of whitewash, or at least white paint. Over the years, we removed that as part of the scope to clean it up and expose the masonry. And became evident that this was an historic wall from an even older building on the site of the photographer warehouse there had been the Hibernian school, and that was used to educate orphan children of sailors who perished at sea. And it was built in the in the 1700s so there was quite a sizable chunk of this. This wall had been used as as the external wall of the warehouse that was built 100 years later in the 1800s so this was worth saving. So unless this was discovered, the project was actually redesigned, went back for revised planning, where this wall was made a feature of fabulous walls, but 20 meters long, had a few of the the windows and door openings were still still evident in them. They had been blocked up with modern block work. So they were they were cleared out, opened up again, and new suitable windows were put in as part of the conservation effort. And this was exposed. So yes, I did often think, chatting with our own crew there, you know, do you think there's anything that we're building now is going to be refurbished in 100/150 years time? Probably not.

Dusty Rhodes  22:22
Let me ask you about your mind space, about something that engineers of 200 years ago today, and I'm sure in 200 years time, the impact of deadlines and budget changes and all that kind of stuff, when you're hit with uh oh, that's going to add another six months onto a project, or that's going to cost us an extra 250, 500 grand on the project build. How do you handle it? Do you sit back and you very cool person to kind of go, right? We'll work through it. Or do you panic?

John Gavigan  22:52
Try not to panic. That's for sure. As an engineer who has kind of evolved as a project manager in my career, you learn different problem-solving techniques. You develop analytical skills where you can assess a different problem in many ways. That's, you know, an engineer solves problems, and that's, that's, that's a lot, a lot of what we do.

Dusty Rhodes  23:15
And I think that's probably what I'm asking you, John, is kind of what, what is your problem-solving thinking. Like, you know, when you, when you're hit with something, do you have a process of of how you handle that?

John Gavigan  23:27
Well, I won't give you away all of my secrets, yeah, just look, I mean, when we, when we're managing a project, there's, you know, 100 or 200 people will be on those sites that I've just described there. So my number one responsibility is the site lead is to make sure that all of those, all of those people, go home safely at the end of every day. And that's not to be understated like there's this huge heavy equipment, there is a lot of potential hazardous activity goes on to build a 4050, 60 million euro project in the city center. As I mentioned, there's a lot of vehicular movement as a lot of kids going on that that has to be the primary concern, coupled couple with that responsibility, you need to deliver the project on time, but that can never supersede the the importance of doing it safely. So in fairness to the industry, then the client based in the consultant base that we would deal with, there is generally an understanding of that. I mean, there is an understanding of that so that that's a given. How do you improve a project when there's something new, some curveball gets, gets sent to you that requires extra time. You know, you can, you can put additional resources on the project, you can work longer hours. You can start doing night shifts if, if needs be. There are ways and means, and typically it's it's additional resources. But that's not always straight, straightforward. The best answer I would have to avoid that situation is communication and lots of planning and lots of discussion to. To make sure that any changes can be incorporated. There's lots of lots of knowledge and lots of skill in the industry. If something is landed on you, if not time to think, then that's, that's, that's when problems arise. But if there's communication across all stakeholders, it's generally possible to find, find the solution. The other element of every project we have to have to consider, as you mentioned, is the commercial side, which that generally happens. And one of my ex-bosses once told me, he said, people will always remember if there was a serious accident on the site. People will always see the quality of a job when it's when it's finished, because it's there for years after, he said people, generally, only very few people, will know if a project has made money or not, if it's commercially successful. And he said people will forget if it was a few weeks or a month late. The most important elements of a job are safety and producing a good quality, because people will be walking by the front door of it for years to come, and we'll always see what it looks like. I've always remembered that, and I think there's a fair amount of truth in that.

Dusty Rhodes  26:05
Well, listen on that, on that scale, and that's great advice you've got. Is there a piece of career advice that you wish that you had received earlier that you could now impart?

John Gavigan  26:16
Well, and if somebody was to come to me and asked me about a potential career in the construction industry. I would definitely promote it. And as I mentioned earlier, it's it's very diverse. There's no There's no such thing as ever having a boring day. But like I mentioned there, every every project has, has its challenges. The timber trusses on on the roof, on the on the keys, there's a triple basement excavation with the special attention to another Georgia. Georgian building is the cantilevered and controlled deflection of a two story steel, steel frame up at four and fourth and fifth stories. There are things that definitely take the potential for boredom out of your out of your day. There's never a dull moment. Every project is different, and every project is effectively like a new job. So if you're, if you're working with a group of people and things, things are going well, that's great, but there's always difficulties. You know, there's light at the end of the tunnel. Most projects are only on site for, you know, 1212, to 18 months. I would encourage anybody coming to the industry to do what they like, study something that that you like, and if that takes you down the construction route, then great. I mean, there, there are opportunities to work, work in design, work for a consultant, work for a building contractor, and you can specialize in any number of areas. Sustainability is a continually growing part of the industry, and we've, we've a lot of people. We have a full team of people working in that whereas 10 years ago, that was a relatively new part of the industry. So there's lots to do.

Dusty Rhodes  27:55
Very true, very true. If you'd like to find out more about John and some of the topics that we spoke about today, you'll find notes and links in the description area of the podcast and I'll make sure to include photos and links to the two projects we were talking about which was 10 Molesworth Street and also the Tropical Fruit Warehouse that we were talking about earlier as well. But for now, John Gavigan, regional director of PJ Hegarty. Thank you so much for chatting with us. 

John Gavigan  28:17
Thank you very much. 

Dusty Rhodes  28:18
If you enjoyed our podcast today, do share with a friend in the business just tell them to search for Engineers Ireland AMPLIFIED in their podcast player. The podcast is produced by dustpod.io for engineers Ireland for advanced episodes and more information on career development opportunities, there are libraries of information on the website at engineersireland.ie. Until next time from myself, Dusty Rhodes. Thank you very much for listening.