Heavier Vehicles in Aging Parking Garages Are a Recipe for Disaster

Vehicles extracted from the building lined the street after a multistory parking garage in New York City collapsed on Tuesday. Photo: John Lamparski/Getty Images

Emergency crews have begun to dismantle the century-old Financial District building on Ann Street that suddenly collapsed this week and killed one person. While some initially pointed to the building’s age and history of violations as a potential cause, it turns out that the size of the cars parked inside might have also been a factor. As former New York City buildings commissioner Robert Limandri said Tuesday, forensic investigators were focused on the 50 or so vehicles parked on the roof. “The weight of those automobiles — they were not as heavy as in 1950 as they are today, perhaps,” he said. “And the idea is to be able to identify if they were using the structure appropriately, and then also that it was being maintained.” Earlier this month, U.K. structural engineers Russell Simmons and Chris Whapples had already warned about the danger of older parking structures being stacked with heavier electric vehicles and made recommendations for how to confront an oncoming crisis, including changes to how garages operate. Simmons discusses what big cars do to aging buildings, what cities and operators can do to prevent such a tragedy from happening again, and one worst-case scenario that not enough policymakers are talking about.

I just reread what your colleague Chris Whapples said a few weeks ago and felt like I was being punched in my gut: “I don’t want to be too alarmist, but there definitely is the potential for some of the early car parks in poor condition to collapse.” What were you thinking when you saw the news from New York this week?

My first thought is it’s obviously awful that someone’s been killed. So terrible. We’ve been looking at increased risk of potential structural failure as a result of increased vehicle weights exacerbated by electrification of vehicles. But it’s also exacerbated by the underfunding of these structures. As a member of the public, you would reasonably use these buildings and think they’re absolutely going to be secure and sound, but in many cases, they’re not.

Officials said the failure happened when the second floor fell into the first, causing all the floors to pancake all the way into the basement. Then the emergency management department said the weight of the vehicles on the top floor may have been a problem … I am looking at these photos and counting almost all SUVs. Structurally, what happens in a collapse like this?

I can’t speak to the U.S. but I can tell you for sure what is happening in the U.K.: The structural efficacy of many of these buildings is just completely unknown. They’ve been left unchecked for decades and then you’re adding more vehicles, which weigh a lot more than they used to. Additionally, these buildings are under a significant amount of use. They’re largely open to the elements. They’re often damaged. And this goes unchecked as well. So the answer is increased vertical load plus increased degradation leads to collapse.

You warn that cars in the U.K. are getting heavier due to the increased weight of EVs. But here in the U.S. we have much heavier SUVs already that are also going electric: In the U.S. over the last 20 years, new vehicle weight has increased to an average of 4,289 pounds. In this instance, we have a building that went up in 1925, then was converted in 1957 to a parking garage. It was clearly not engineered for today’s cars. What are those heavier vehicles doing to a building over time?

It’s putting an increased amount of vertical load on these buildings, without any doubt. But the other thing to be aware of is the increase in block parking. So the car park will have been laid out for traditional parking: cars being parked in bays with an access aisle. If the cars are block parked, not only is the car on average heavier than the original design load, but there’s more of them in the areas not designed for it. You might not think it’s overloading because it’s a great big concrete building. But these buildings are often much more fragile because they’re designed to be so efficient in construction and not to have lots of redundancy. They do a very good job of adhering to design codes, generally speaking, but when we’re increasing the point load, we’re putting something which has been designed efficiently under even more pressure. Unless people work out what the condition of their building really is, we don’t know how much more they can take.

There were some 20-year-old open violations that showed first-floor cracks in the ceiling slab, although it’s not clear if that caused the collapse because a subsequent 2013 inspection said there were no problems. But a new city law was put in place in 2021 that will require all parking garages to be inspected by 2027 — and this Ann Street garage was due for one this year. What specifically should inspectors be looking for?

First, it’s really, really important that responsibility stays firmly with the owners and operators of these facilities. If they’re not safe for use, they should be shut down, and the owner-operators, if they want to continue using them, should do all they practically can to ensure that they know that the buildings are safe. Then, there’s inspections and there’s inspections. You can’t just have someone taking photos of cracks. A structural-engineering approach to inspections and testing and appraisals is needed to know what condition the building is in. In the same way that you wouldn’t dream of not having a regular fire-risk assessment done, why on Earth should you not have a structural assessment done of a building which takes such a hammering?

The building on Ann Street “pancaked, collapsed, all the way to the cellar floor,” the acting head of New York’s buildings department, Kazimir Vilenchik, said at the scene. Photo: Ed Jones/AFP via Getty Images

The British Parking Association is going to be updating its design guidelines on recommendations you and some other engineers are making, based on both automaker trends, where electric vehicles are about one-quarter heavier than their gas counterparts, and the fact that the U.K.’s gas-car ban is arriving quickly: namely, increasing load limits on concrete parking-garage floors by 20 percent. 

The recommendations will be for engineers to adopt a greater load when they’re designing new buildings. So in other words: When you’re designing these buildings, assume that the cars are going to be heavier. But that’s just for new buildings. There is far more existing building stock than there is new buildings. And that’s the bigger problem.

What should be done to structurally strengthen an existing building?

There’s all sorts of clever stuff you can do. If your column is liable to failing or exploding outwards, you simply wrap it in Kevlar fiber and you can increase the capacity of that column really significantly. And if you’re talking about the decks or soffits in the ceilings, then you can use carbon strips to add strength in terms of stopping bending or sagging. You can fire carbon-fiber strands into columns and splay them out the other side so that you get a really nice anchor point. These are things you can do which are not massively cost-prohibitive.

And there are other recommendations you have which are more about operations, like reducing the number of parking spots, and you even suggest that garages might ban cars of a certain weight from entering?

What you can do is manage the building in a different way so you’re not overloading it to that point. Maybe you want to be more discriminatory about heavy vehicles, or only have them park on the ground floor. For car-park owners and operators who are really commercially savvy, maybe make the spaces bigger and charge a bit more. If you make the spaces, say, twice as big, and you don’t block park, then you’re going to reduce your load in that bay by 50 percent. Now you’ve reduced your weight but the building is going to get less use and the attendants are going to have less work to do. So you increase your rate that you’re charging people and you’ll attract the people that can afford to pay a bit extra.

In the United States, just 14 states currently tier registration fees by vehicle weight because of the damage heavier vehicles do to roads. Maybe we should be charging by vehicle weight to enter a garage.

In the U.K., we have a solution for this. The way each vehicle is registered means approved operators can find out some data for each car using the license plate: the type of propulsion, color, and curb weight. You can have a camera that reads the license plate, and immediately knows how heavy it is, in theory. And at that point you can have an operation system which does pricing and guides some cars this way, some cars that way.

And a lot of U.S. garages already use license-plate readers, so that could work. Making it easier for garages to assess car weights seems to be one way of preventing catastrophic incidents like this, especially since we’re really putting a lot of the burden of electrification on parking garages. This is where we’re installing car-sharing and charging facilities. They’re not going away.

In a lot of situations the economics of it are going to be prohibitive with the recommendations we’re making in terms of new builds. The price of construction goes up, which puts the price per space up. It all needs to be priced higher in order to get a return. At the same time, the government is pushing electric vehicles, but our infrastructure is not ready yet. Soon it’s going to be illegal to buy non-electric cars. The government needs to step in to build these facilities, which are often public.

From that line of thinking, should we really be adaptively reusing these 100-year-old buildings for parking at all?

I’m all for breathing life into existing buildings and what we call circular construction. Repurposing prevents other inefficiencies. But it has to be done in a very careful way. You have to know the limits of the building elements for what you’re going to retain, and how you can impose your new increased load and plan for worst-case situations — like a very fast electric vehicle slamming into a wall.

I hadn’t even considered that scenario. These new electric vehicles do accelerate very fast, which I’ve written about before.

The thing that a lot of people are missing here is horizontal load. You slip off the clutch of a 1970s Ford Fiesta and you might have a ten-mile-an-hour impact on a column or a wall. If you accidentally press the accelerator on a new electric SUV, you’re going very, very quickly in a two-ton car in no time at all. You’re going to hit a wall or a column that is not designed for that. I’m actually a bit more worried about these very fast electric cars, which weigh more and impose a huge additional risk horizontally — not just vertically. I would put money on an electric vehicle or two leaving the side of a car park in the next few years. The edge protection of these buildings is not designed for this. When some whizzy, powerful, giant electric car smashes into one of these walls, it’ll just go straight off the side of the building.

New urban nightmare just dropped.

That’s why I say don’t just assume these buildings are all sorted, because some of them are being managed by people that simply don’t have the funds to maintain them. They’re completely exposed to rain and snow. They get driven into, bashed about. As soon as you finish building one, they start to fall down.

This interview has been edited and condensed.

Heavier Vehicles in Aging Garages Are a Recipe for Disaster