Pedestrian LOS Problem

[niwde]

Can you please help me why in the 508 NCEES sample question the answer is LOS E? Base on my computation with CERM table is LOS D. I don't if I am wrong.

508. A 10 FT WIDE SIDEWALK HAS AN EFFECTIVE WALKWAY WIDTH 6.5 FT. THE PEAK 15-MIN PEDESTRIAN FLOW IS 1200 PEDESTRIANS. THE PLATOON ADJUSTED LOS IS MOST NEARLY;

A) LOS B

B) LOS C

C) LOS D

D) LOS E

 

[Dexman PE PMP]

The eyeball test says 1200 pedestrians in a 6.5' wide sidewalk is way beyond capacity. I would classify this as LOS F personally...

 

[niwde]

Dexman,

the formula for this is

Vp = V15peak / (15 x Weff) = 1200/(15x6.5) = 12.3 ped/min-ft.

The CERM table 73.15 says LOS D

 

[mrt406]

The question asks for the Platoon Adjusted LOS. The table you're referencing is only for Average Flow LOS, which doesn't take into consideration that platooning is occuring. If you look in the HCM, table 18-4, the Platoon-Adjusted LOS criteria are listed out. With that adjustment, 12.3 p/min/ft falls in the LOS E category.

 

[Road Guy]

That's why it's good to use the HCM instead of the CERM. The folks that write the questions probably look in the CERM and find questions that looknlike what's in the CERM when you really need the HCM..

A few of those got me the first go round...

 

[niwde]

Thank you guys,

So, It means I need to have the HCM during the test...

 

[lady_j]

Thank you guys,

So, It means I need to have the HCM during the test...

I would advise on having the HCM with you during the test. I belive that they are still using the "old" edition (check the required references on NCEES website for edition). Ask around - if your office doesn't have one, someone you work with might...I think anyone who has taken the PE within the last 10 years would have used that book.

There are also example problems in the HCM that are great for additional practice.

Also, Goswami's "all-in-one" sums up the tables in the HCM better than the CERM, in my opinion.....

Good luck!

 

[Road Guy]

Yes it's worth buying..especial if your doing transportation

What's also helpful is to learn how to use the HCM "quick cheat sheets" for determining level of service and saturation flow rate type problems. It looks tricky but the cheat sheets (work sheets) give the formulas and tell you what page the factors are on and such..