An Engineering Collapse

Have you ever experienced a situation where just because you work in a specific field that people think you know everything about it? After the pedestrian bridge in Florida collapsed back in March, I have received the question of what happened to it numerous times. Family, friends, and people I’m just meeting for the first time have asked why it collapsed and act like I should know what happened to it since I work in the Civil Engineering field but in reality, I don’t work with bridges at all and have no idea what happened to it, so I decided to do some digging.

One of the first issues was that the project was behind schedule and over budget (wait, aren’t all projects?). In addition, the engineers were asked to move the signature pylon of the bridge to accommodate for possible future road expansion, changing their design (below image shows a rendering of the final design). Videos that captured the incident show that part of a prefabricated segment of the bridge started crumbling on the same end where the pylon redesign was to be located. The pylon was to be installed later into the project with each prefabricated section being able to withstand all the forces they would experience before completion of the project. An engineer had reported cracks in the same location where the bridge failed two days prior and stress testing was being conducted the day of the collapse. There was even a meeting the same day in which engineers and state officials discussed whether the cracks in the structure presented a safety risk.

Some engineers involved in trying to find the reason behind this collapse have said that any slight modification to a bridge design is inviting possibilities for failures. The same care and attention that the original design had does not always continue once a change is proposed and designed for. The proposed design change put the engineering team further behind schedule and over budget. This project was being federally funded and the engineering team was worried that funding might run out before they could complete it causing them to further try to speed up their designs.
Engineers and other officials are still looking into the exact cause of the bridge’s collapse while FDOT and the engineering team responsible have been hush-hush for the most part. Although all projects are different, a valuable lesson can be learned from this. Time and money are always key driving factors for projects, but they should never be able to dictate the final design. It may take some more time and money, which leads to unhappy clients, but sometimes that is what is needed for a successful project.

Possible Rain Today

Possible Rain Today

I took the liberty of jotting down some bullet points in case it rains today. They may sound like they are sarcastic because they are.

It has been less than 24 hours but this is EXTREMELY important. There is a chance of rain today. Now, don’t panic, but this means a few things.

1. There is a chance it may rain.

2. There MAY be water on the roads. This is ok.

3. Streams may have more water in them AND the water may be brown.    Actually, it WILL be brown. Again, this is common all over the world.

4. Water will flow into storm inlets and into pipes and then out onto the ground.    No worries, this is intended. If you see this, DO NOT PANIC.

5. This is critical. Detention basins and sediment basins WILL have water in them.  AGAIN, DO NOT PANIC, this is an intended result. People like me, we actually WANT this to happen, it makes me happy when this occurs.

6. Water may also be “running” (flowing) through swales around your house.   Once again, DO NOT PANIC, this is ok and perfectly normal. This happens all the time while you are sleeping and when you wake up your yard is fine. Seeing it may be traumatic, just look away, turn on the TV or read a book until it is over.

PS – DO NOT read a book about storms or rain or watch the following movies – The Perfect Storm, Twister, Geostorm or White Squall.

Hang in there, we will get through this!

Zoning: When, Where, Why, & How

Zoning: When, Where, Why, & How

Have you ever had a dream crushed by a Zoning Ordinance? Have you ever wondered what brought all these wonderfully specific laws into play? Legend has it; we owe it all the Equitable Building.

The Equitable Building, designed by Ernest R. Graham located at 120 Broadway in Lower Manhattan, is a 38-story steel frame building. It provides 1,200,000 square feet of rentable office space and the capacity to hold 16,000 office workers. Graham was instructed to design the largest building that could fit on site, and he did not disappoint. The Equitable Building rose straight up from the street lot-line without any setbacks! As you can imagine, the neighbors of this massive building were not pleased. There were complaints of blocked sunlight and less air flow. In response to the Equitable’s construction, the Heights of Buildings Commission in New York City was formed.

The final report of the Heights of Buildings Commission was delivered June 2, 1916. It presented the first Zoning Resolution of the City of New York, also known as the first comprehensive zoning ordinance in the United States. The report included a zoning map which restricted building heights for the entire city based on the setback principle. The setback principle was more complex than stating a simple fixed maximum building height. Depending on the zone, the building height could not pass a certain ratio to the width of adjacent streets. However, extra height could be gained for every foot it was set back from the street. For example, in a one and a half-district, adding a foot to your building setback gained you an additional three feet in height. Additionally, in any zone, 25% of the lot had no height restriction at all. The idea was to keep New York City’s dense streets more open. The Zoning Resolution Act also set rules for how land could be used in certain areas of the city, such as industrial areas versus residential areas.

Congress passed A Standard State Zoning Enabling Act in 1922, using the Zoning Resolution of 1916 as a blueprint. Modifications were made as time went on. And we have come full circle. Imagine what a dim square world we would live in without zoning!

Golden State Mandate

Golden State Mandate

In our line of work, we deal with countless municipal regulations that dictate everything from the footprint of a house to the type of sewage disposal method. Although we can achieve credits with certain regulatory entities by incorporating solar panels into the design, there is no law in Pennsylvania that requires houses to have them. But that is not the case on the west coast.

Back in early May, California introduced a law that states that new houses constructed in 2020 and beyond must have solar panels. What was previously a choice for each individual homeowner is now a mandate for anyone looking to build a house in the golden state. While California has long been at the forefront of progressive environmental regulations, this comes at an interesting time. High housing costs continue to be a concern and including solar panels to the build would bump up the cost about $10,000, experts estimate.

It will be interesting to see what impacts this has moving forward. The solar industry already has a huge market in California and this law is only expected to grow that. On the flip side, homebuilding companies are predicting a decline in stocks as a result of the law. Only time will tell…

What are sinkholes and how do they form?

What are sinkholes and how do they form?

Ever wonder how a sinkhole can seemingly appear out of nowhere and swallow up people’s cars or homes in minutes? Turns out, the makeup of the dirt beneath your feet plays a large part in the creation of these sinkholes.

We’ve seen this problem start to occur more frequently over the years in places like Florida, Kentucky, Pennsylvania, and, most recently, the White House. They can vary in size from as small as a foot to large enough to consume an entire building. One such instance of this phenomenon occurred back in 2014 when a large sinkhole suddenly opened at the National Corvette Museum, swallowing eight of the Corvettes on display into its depths. Luckily, the sinkhole formed during the night and no one was injured. The building had been up and running for nearly 20 years before this happened.
These sinkholes form typically when Karst features, meaning soil and rock composition of either limestone or dolomite, are slowly dissolved over time by water. This leaves a void in the ground that could become unstable and collapse given the right conditions, which means a major problem later down the road. Sinkholes typically take a long time to form, occurring over the span of months or even years. Warning signs typically include rapidly forming depressions and holes in the ground or cracks appearing in walls and pavement.

Since there are many karst soil formations in Pennsylvania, it’s an important feature to look for when working on a job that requires the runoff to be infiltrated on site. This can be done by checking eMapPA or hiring a Professional Geotech to take borings across the site and determine if the offending materials are present. If nothing is found: great, business as usual. However, if Karst is detected, then the runoff will need to be mitigated without infiltration. We avoid infiltration beds on sites with karst areas because beds will act as concentrated sources of water which could accelerate or cause the formation of a sinkhole.

Depending on the scope of the project, this could require the use of underground storage tanks that will hold the runoff and slowly release it into the Municipality’s storm sewer system. If the site isn’t close enough to connect, then BMPs such as rain gardens, vegetated roofs, and shallow detention ponds can also be used in lieu of infiltration.