Wednesday, April 13, 2011

ATC 20 - To Buy or Not to Buy?

Is ATC 20 Worth the Investment?

ATC 20 is titled “Procedures for Postearthquake Safety Evaluation of Buildings”. The Applied Technology Council produced this 152-page book in 1989. It is an analysis of safety evaluation procedures following an earthquake. It details methods of evaluation, ratings of evaluated buildings, and provides excellent sketches and photos of earthquake damage.

Will you need this during the exam? After my seismic test, a young lady next to me said she had been told at her firm (a traffic engineering agency) that she needed only “the Hiner book”. She felt she had done well. However, she seemed a teeny-bit surprised when I told her I had answered three questions using the ATC books.

There are three ATC 20 books: ATC 20, ATC 20-1, and ATC 20-2. ATC 20-1 is a small pamphlet, a “Field Manual”. Just 4.25” x 7.25”, it is hand held and designed to be used to quickly translate visible damage during rapid assessment into ratings of “SAFE”, “Potentially UNSAFE”, or “UNSAFE”.



In today’s world of tilting earth, shifting magnetic fields, plate tectonic weapons like HAARP, and massive earthquakes like Sichuan, Haiti, Chili, Indonesia, and Japan, we engineers need to be ready to provide emergency services. Safe buildings can reopen for business. Safe homes can provide shelter. In addition to engineers, city inspectors are permitted to perform inspections. However, the engineering profession should step up and meet the responsibility as best as possible. You will need this book on your shelf.

Unlike the young examinee next to me, it is appropriate to seek advice beyond the people in your office. Go directly to the exam website and write down titles of the required references and books. Use the link below. Find the exam you will take, download the exam criteria (a pdf), and scroll down for the list of required texts:


There are 55 questions on the California State Specific Seismic Exam (2.5 hours = less than 3 minutes per question). If you can answer 3 questions using the ATC 20 books, that is 3/50, or 6% of the available questions. (Note: 5 questions do not count toward your score. Those are new questions under trial, being calibrated for future exams.) Passing is set by a cut score. This means it is a competition. You need to perform better than the majority of the others testing with you. Typically, (according to various unofficial sources) 70% is expected to be a passing score. 3/(.7x50) = 8.6%. Basically, you are given an 8.6% advantage over your fellow examinees if you will:

  1. Buy the ATC 20 series.
  2. Review all three publications when they arrive.
  3. Bring them with you to the exam.
That is a significant benefit. The questions I answered could have been reasoned with basic engineering knowledge to eliminate (maybe) one option in just one of those three. You need these books, and you need to be familiar with their contents.

I did not read every page. I spent about two hours reviewing all the material, reading the main passages, and writing a few summary notes in white space (Use ink for this, not pencil). During the exam, I was able to recognize I needed the ATC books, and knew what I needed. I flipped through until I found the sections I needed to answer the questions (easy with so many sketches and photos).

I took the April, 2010 seismic exam without these. I never knew I needed the books (I did not have them.) I took the April, 2011 exam with them, and I am sure I answered those three questions correctly.

Buy ATC 20!

See costs of all the Seismic Principles exam reference books and where to get the best buy. 

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