Quiz #26

[John QPE]

Well, it looks like most, if not all, of the results are out. So let's get these started again.

If you have already passed the exam, feel free to PM you solutions, but please do NOT post it in the comments.

A horizontal curve with 6* of curvature (measured at the CL of the 12' inside lane) is being designed for a highway with a design speed of 70 mph. The grade is level, and driver reaction time is assumed 2.5 secs. The minimum number of feet, an object can safely be placed from the CL of the inside lane is most nearly:

A. 62.5

B. 68.5

C. 72.5

D. 74.5

 

[GoldfishJack]

You're a good man John. Although I didn't post much prior to taking the PE, I did do all your quizzes and they definitely put me on the right track towards focusing on methods and problem solving.  :thankyou: lusone:

 

[John QPE]

You're a good man John. Although I didn't post much prior to taking the PE, I did do all your quizzes and they definitely put me on the right track towards focusing on methods and problem solving.  :thankyou: lusone:

You're welcome! Now it's your turn to return the favor to the board, and help out the future test takers.

 

[GoldfishJack]

You're welcome! Now it's your turn to return the favor to the board, and help out the future test takers.

I'll do what I can  :B

 

[ptatohed]

You're a good man John. Although I didn't post much prior to taking the PE, I did do all your quizzes and they definitely put me on the right track towards focusing on methods and problem solving.  :thankyou: lusone:

What about all of ptatohed's quizzes? 

 

[GoldfishJack]

What about all of ptatohed's quizzes? 

Ptatohed's quizzes were super helpful too. I apologize for leaving you out. :brickwall:    arty-smiley-048: lusone:

 

[Beej]

B

 

[ptatohed]

Are we really up to #26 already?  Wow. 

I get what Beej got.  This requires assuming the Degree of Curvature is arc basis (DA), and it requires assuming the deceleration rate, a, is 11.2 ft/s2.  It also seems to work out nicer if the calculated stopping sight distance (SSD) is used, not the design SSD. 

Calcs upon request. 

 

[John QPE]

It has been my experience with the practice exams (and in other studies), that knowing when to use the "assumed" values are just as important as knowing how to do the problem. Try it a couple ways to show that you "really" understand the problem.

 

[DuckFlats]

Why do you assume to find R based arc definition as opposed to chord? 

 

[ptatohed]

Why do you assume to find R based arc definition as opposed to chord? 

As a general rule, the degree of curvature based on arc def, DA, is used in roadway design and the degree of curvature based on chord def, DC, is for railroad design.  So, unless stated in the problem, you can typically assume arc def if it is a roadway problem and further direction is not provided.  Even then, if you solved for DC, it shouldn't be too far from DA anyway and you'll likely still get the correct answer.  This applies to the 8hr Transpo and the CA-Survey exam. 

R = 5729.6 / DA = 5729.6 / 6 = 954.9'

R = 50 / sin(DC / 2) = 50 / sin(6 / 2) = 955.4'

 

[DuckFlats]

Thanks. I was having calculator errors and getting different solutions.