NCEES sample exam, question 515

[Predgw]

Min clear zone on a low speed rural collector and rural local road is most nearly:

I said 10' which was correct, however I can not find the langauge the answer refers to anywhere in the Green Book. I'm wondering if this is a case of the current green book differs from the edition that was used to make the sample exam.

I got my answer by looking in the roadside design guide, based on quick view of the table on page 3-3, the smallest clear zone distance is 7' on a 40 MPH road with ADT under 750. 7' feet is not an answer so i picked 10'

I dont like how I could not verify the answer. My method realizes on the speed and traffic count, both of which were not given.

Any thoughts.

The answer states based on the Green book (2004) "for low speed rutal collectors and rural local roads, a min clear zone width of 10' shall be provided"

I can not verify this language in the current green book (2011)

Thanks

 

[tmanker]

I looked for a while but did not find this either. I almost wish I would have used the 2004 green book because most sample exams and many other sources still reference that manual.

 

[Predgw]

I hear you. The 2010 HCM is even worse. At least with the green book, I use that for work. Not so much with the HCM.

 

[ptatohed]

Guys, I don't have my GDHS6 with me right now but I have the GDHS5 I used for studying "back in my day". In my GDHS5, page 319, it reads "For low-speed rural collectors and rural local roads, a minimum clear-zone width of 3.0 m [10 ft] should be provided".

If you want to look for it in your GDHS6, it's in my GDHS5 Chapter 4 (Cross Section Elements) under the heading "Horizontal Clearance to Obstructions".

And I also have in my notes that this is without a curb. With a curb, the cz can be as little as 1.5 ft (face of curb to obstruction).

 

[tmanker]

Thank you. I may need the help of a busch light to find it tonight, but find it i will!

 

[Predgw]

I left mine at work, but I'm almost certain I looked over that section thinking that made sense to find it there. I will take a look tomorrow when I get back to the office.

Thanks

 

[ptatohed]

I just took a look (I forgot I have a non-searchable PDF of the GDHS6 on my jump drive). I can not find it in Chapt 4 either. It looks like the info would have been on pg 4-15 Sect 4.6.1 (Clear Zones) if it were to be there. It seems the GDHS is very careful to refer you to their other books (RDG, etc.). Which I suppose is smart, to avoid contradictions amongst books which often results when two books try to report on the same topic. I can't find the 1.5' clear zone from curb face to obstruction in the GDHS6, as mentioned in the GDHS5, either. Seems like you guys should just stick with RDG4 for all clear zone problems.

 

[BrettL0726]

In GDHS-6, pg. 6-8 toward bottom of page. "Clear Zones" section says "For low-speed rural collectors, a clear zone width of 7 to 10 ft is desirable."

 

[ptatohed]

In GDHS-6, pg. 6-8 toward bottom of page. "Clear Zones" section says "For low-speed rural collectors, a clear zone width of 7 to 10 ft is desirable."

Good find!

 

[Predgw]

Great. Thanks.

That does confirm the books have changed, and my logic would have been solid as the Green Book now matches the RDG. Thanks

 

[f1999587]

Hello All,

I am sorry for posting this question as a follow-up thread. This is the only active thread that I see. As you know, the exam is next week. trying to get a response.

This is related to Geotech AM Question in the NCEES Practice book Problem No. 116. This is a retaining wall problem. What I don't follow is that, for the triangle part of the retaining wall, the moment arm length is indicated to be 2/3. But I think it should be 2/3 of the length (or the base of the traingle). so, it should be 2/3 (2ft) equal to 4/3.

can someone clarify?

Thanks.

 

[ptatohed]

Hello All,

I am sorry for posting this question as a follow-up thread. This is the only active thread that I see. As you know, the exam is next week. trying to get a response.

This is related to Geotech AM Question in the NCEES Practice book Problem No. 116. This is a retaining wall problem. What I don't follow is that, for the triangle part of the retaining wall, the moment arm length is indicated to be 2/3. But I think it should be 2/3 of the length (or the base of the traingle). so, it should be 2/3 (2ft) equal to 4/3.

can someone clarify?

Thanks.

I am not clear what you mean by this: "This is the only active thread that I see". ??? Anyway, it looks like you also started a new thread on this topic on the Geo forum. I'll respond there.