In Case You've Wondered

My blog is where my wandering thoughts are interspersed with stuff I made up. So, if while reading you find yourself confused about the context, don't feel alone. I get confused, too.

If you're here for the stories, I started another blog: scratchingforchange.blogspot.com

One other thing: sometimes I write words you refuse to use in front of children, or polite company, unless you have a flat tire, or hit your thumb with a hammer.

I don't use them to offend; I use them to embellish.

jescordwaineratgmail.com

Tuesday, January 18, 2022

Building a Bridge - Construction Part 1 - Getting Started

After a contractor is notified they won a bid, a few things happen over the month, or longer, period before the ground is broken. First is the getting all the submittals for materials, subcontractors, EEO paperwork, insurance certificates, and any special designs, such as a falsework plans. I have no idea how many in a large company are delegated to this task, but know smaller companies may have only a few. During my career, it could be a daunting task, since I worked for a small company, and had other things to do, but it was part of my job description. Bidding was too, but it wasn't full time. There were way too many pieces of paper to be accumulated, and too much of it was bureaucratic make work. My supervisors/owners and office staff helped, and we scrambled to complete everything before the pre-construction meetings. Large bridges were beyond our bonding capacity. We did build some small bridges, but work on larger bridges was as a subcontractor for various. 

One task that was very important after winning a bid was creating a spreadsheet with all the bid items. Included were the anticipated labor costs, material costs, subcontractor costs, overhead items, profit, TIBS (taxes, insurance, BS/miscellaneous) and time. There were dozens of bid items included, and the information was needed to load the project into the accounting program. I know there are canned software applications out there for construction project management, but we never really had the need for the expenditure. We all came from the old school where we originally worked with columnar tablets, and the accounting was done the same. Years of building spreadsheets developed a method to take care of all we needed, and the canned accounting software was the only one that could handle the bid items when we first bought it. Over time, the software was upgraded, and we stuck with it. Manipulating spreadsheets became second nature. 

With TxDot work, and I imagine most other states, and municipalities, the placing of barricades is the first task. This may only be a handful of temporary advanced warning signs, but may include temporary striping, barriers, and message boards. Without these things, and SW3P items (storm water prevention) the project is not allowed to start. Storm water runoff items can a few feet of silt fence, or a elaborate configuration of silt fence, soil erosion logs, and rock filter dams. 

After the barricading is completed, field survey crews station the project, place temporary controls, and are usually available during the project for surveying tasks. Their efforts require a good understanding of the plans, and the instruments they use. While some of the surveying is completed by GPS, accurate measurements require a total station. 

Total stations aren't affected by the weather, shade, or the failure to allow the GPS instrument the time required to be as accurate as possible. Some, called robot guns, can be controlled by the controls on the rod, which can make accurate measurements easily performed by one person. It removes the job of one person, but they're tens of thousands to purchase. During my career, it was one of those items I knew I would never see. It was far beyond what a small company could justify for what little use it would have. Mine required someone to hold the rod, and I was happy to have it.

Once a total station is set up, known coordinates are shot to determine the current location of the total station, the height of the total station above a point, or the ground, is entered, the station can be used to either record, or find locations. Elaborate software allows placing offsets, the points in a curve, and does so with accuracies within a fraction of an inch. Coordinates can be downloaded into the instrument, and when set up correctly with a good rodman, be more accurate than any measuring tape over long distances. Wood stakes, with nails, are used to set temporary controls. These are surrounded with lathes covered in barricade tape. Lathes, with information written with a sharpie, are used to show stations. These are holy objects on a construction site, and disturbing any is frowned upon; especially temporary benchmarks. 

Paint may show stationing, or known underground utilities. With stationing, the paint is a reference for a location. The stationing is a good reference for determining the big picture of the project, and for a quantity reference in the future. The stationing on the ground may show a discrepancy in the plans, or help with determining access to parts of the project. Regardless of how accurate plans can be, plans don't indicate ground condition, or the fact the local rancher has a little drive he uses daily. With ground conditions, the planned storing of materials in a boggy area is usually a bad idea. With the rancher, he probably owns half the county and hob nobs with state officials a few times each year. Both are problems that need to be handled before the crews arrive, and a good superintendent takes care of both contingencies way before that happens.

Paint for utility marking is color coded. White is for the contractor, orange for communication cables, red is for electrical, green is for sewer, blue is for water, yellow is for gas, and none can be assumed to be marked correctly. Some markings may match the plans, but others may indicate an underground utility missed by the initial survey, and cause problems. One of my worst situations was water line running right through the center of a large proposed junction box. We had paving to break, a large hole to excavate, and the project was shut down. My calls to the engineer I knew were wasted on voicemail messages, but I was lucky when a supervisor of the water utility happened to arrive on the site. With a few minutes conversation, and cutting off the water main, we broke the paving, excavated for access, and his crew relocated the main in a few hours. 

With enough surveying completed, and required items handled, the next part of the project is embankment, piling, or both. That requires another post.

5 comments:

  1. Sounds to me like you could have easily been an engineer.

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    1. I don't think I could have passed the advanced mathematics. I can work with trigonometry, but calculus escapes me.

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  2. (and fiber optic cable buried 2" into the ground - don't ask how I know)

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    1. I uncovered a bundle of fiber optic cables about the same depth while placing concrete pipe on a project. One of the crew was hand digging to keep the operator from cutting the bundle, which was supposed to be two feet deep, and in a casing.

      I was amazed. Cutting such things can lead to tens of thousands in lost revenue, and the insurance companies usually have something to say about the event.

      On the same project, we uncovered a thousand pair unmarked telephone cable. After an hour wait, me slipping in the trench and bruising my shoulder, the locater arrived to inform us it was an abandoned cable.

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