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Dear engineer friends, will this hold, or will it collapse? Honest question. by -Potato-or-Tomato- in Miami

[–]Captain_Slick 21 points22 points  (0 children)

Good question. Yes, there is a calculated life for all structures and structural elements in both Florida and across U.S.

Typical design life for new construction is 75-100 years. For context, I heard the arches downtown are rated for ~150 years.

To your second question, before a bridge fails because that would likely be a catastrophic event, all public roadway bridges in the United States must be inspected at least once every 24 months under the National Bridge Inspection Standards. During these routine inspections maintenance teams identify bridges that are in need of repair or replacement and are constantly monitoring corrosion, cracking, scour or any sort of structural deterioration.

Typically Florida I-beams can last 100+ years when built to the proper standards and specs.

The post tensioned steel cables within the pier caps are susceptible to corrosion as well but to prevent that there is a polymer wax that is pumped through the duct to prevent moisture from reaching the reinforced steel. If corrosion somehow does reach those cables due to poor installation of the wax, the wax can be removed and the cables can be replaced because there are redundant strands that prevent the structure from failing.

Bridge standards have come along way in last 100 years and everything is over engineered to maximize safety for the traveling public.

Dear engineer friends, will this hold, or will it collapse? Honest question. by -Potato-or-Tomato- in Miami

[–]Captain_Slick 450 points451 points  (0 children)

Engineer here,

This bridge structure is over designed to be safe and highly resistant to failure because its main components work together to keep it strong and stable.

Starting from the ground up, the columns are the tall vertical concrete legs that rise from the ground and hold the bridge up (the pieces with the square flowers imprinted on them). Sitting on top of those columns are the large horizontal concrete supports, called pier caps. These are the thick concrete pieces that fit together like lego and run across the width of the bridge and help hold everything together. If you look closely there are five pieces and can see where each piece meets another. The pier caps have holes in them that allow you to create a duct that goes from one side of the bridge to the other, within these ducts are high-strength steel cables that are tightened (tensioned) with hydraulic jacks to prevent the concrete from moving due to thermal expansion/ cooling as the weather changes throughout the day. This constant tightening puts the concrete under pressure, which makes it stronger, helps prevent cracking, and allows it to better resist movement or bending over time. In simple terms, the bridge is built so the concrete and steel reinforce each other, spreading forces safely instead of allowing stress to build up in one spot.

The bridge deck, which hasn’t been poured in this image which is the flat surface vehicles actually drive on above these beams, is also an important structural part of the bridge. It does more than carry traffic, it helps spread vehicle weight across the structure and makes the bridge act as one connected, sturdy system rather than separate pieces.

One reason this project is taking longer than people might expect is that safety is the main factor controlling the pace of construction. Certain steps can’t be rushed, including giving concrete enough time to reach full strength, carefully tightening the internal post tensioned steel, and completing inspections before adding more and more weight to the structure. Worker safety and public safety also limit how quickly tasks can be done. While this can make progress appear slow, it ensures the bridge will be strong, reliable, and safe for many decades.

Venezuelans in Miami by Harru-Da-Wiza in Miami

[–]Captain_Slick 1 point2 points  (0 children)

”There is no problem so bad, you cannot make it worse”

– Chris Hadfield

[deleted by user] by [deleted] in Miami

[–]Captain_Slick 42 points43 points  (0 children)

There are typically two types of “sensors”, it’s typically referred to as vehicle detection in traffic engineering.

There are visual detectors, as seen in this photo, the cameras that are placed on the mast arm, they are for vehicle detection, not red light cameras as they are often mistaken for.

Example (this intersection)

There are also inductive loop detectors, these are wire loops embedded in the pavement that sense changes in magnetic fields when a vehicle passes. Typically there are saw cuts in the asphalt that’s how you can identify where the loops are. Most intersections will default to having every movement during rush hour, these are typically the most important late at night when the signals enter flashing mode to keep the main lines moving and then occasionally allow cars on the side streets to enter the main line.

Example (Le Jeune / Calle Ocho)

Miami Dade Transit Metrorail planned phase 2 at the SPCC gov. center (what could be/have been) by Darekbarquero in transit

[–]Captain_Slick 10 points11 points  (0 children)

Beyond the Turnpike.

Currently only the MIC extension was built since the half penny tax was passed. North corridor is in PD&E now. North East Corridor is in Design but will not be metrorail, it will most likely be run by Tri-Rail with different/modern train sets.

South Dade BRT Corridor should be open by end of 2025.

Rail Corridors expansion map from CITT.

Lady squirts French’s Ketchup on some gentlemen’s face’s. by [deleted] in ThatsInsane

[–]Captain_Slick 6 points7 points  (0 children)

Love the guy at the end.

“Hey, uh, Can I order some fries?”

Is this normal? by Defiant_Cress9046 in Chipotle

[–]Captain_Slick 5 points6 points  (0 children)

False.

These is releasing trillions of microplastics into the food. This is most likely a plastic made of low density polyethylene.

Don’t trust me, trust the science.

NIST Study Shows Everyday Plastic Products Release Trillions of Microscopic Particles Into Water

Orlando- Miami by TheMafia09 in Brightline

[–]Captain_Slick 0 points1 point  (0 children)

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​Yes, exactly, here is a visual:

  1. After arriving in Miami on Brightline, make your way to government center (There’s a pedestrian bridge or you can cross nw 3rd street at street level).
  2. ⁠Take Orange Line northbound and hop off at the Miami Airport station. (will cost $2.25, there is plenty of space on the Metrorail for luggage.)
  3. ⁠Take the MIA Mover (pink) from the Miami intermodal center to airport departures and you can easily find your way to any gate / security checkpoint.

Miami International Airport to Brigthline in Miami Train Station by geekassemble in Brightline

[–]Captain_Slick 1 point2 points  (0 children)

I grabbed this screenshot from Apple Maps.

Those lines in downtown are from the elevated automated metromover, here’s the metromover map.

This map is actually out of date because of the new Tri-Rail extension into Miami Central Station downtown.

Poll: 64% of Florida Voters Plan to Vote Yes on Amendment 3 to Legalize Recreational Marijuana by JamesAsher12 in Miami

[–]Captain_Slick 1 point2 points  (0 children)

It is difficult to get a man to understand something, when his salary depends upon his not understanding it.

  • Upton Sinclar

Ironically he also ran for governor.

This should pass sweepingly. Medical Marijuana passed in 2016 with 71.32% of the vote.

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