Minimum Green Time

[AJK]

I am working The Transportation portion of the NCEES sample exam. I'm having some issues with problem 501,

which asks for a minimum green time for a signal given the crosswalk width and some other factors.

The solution references chapter 9 of the 1997 HCM, and give the equation: Gp=7+(W/4.0)-Y

I cannot seem to find this equation in my copy of the 2000 HCM. Does anyone know where its at?

I keep coming across equation 16.2 (on page 16-5) which is: Gp= 3.2+L/4.0+(2.7Nped/We)

But you need to know walkway effective width and the number of pedestrains for this equation.

Thanks in advance for your help.

 

[bigray76]

I am working The Transportation portion of the NCEES sample exam. I'm having some issues with problem 501, which asks for a minimum green time for a signal given the crosswalk width and some other factors.

The solution references chapter 9 of the 1997 HCM, and give the equation: Gp=7+(W/4.0)-Y

I cannot seem to find this equation in my copy of the 2000 HCM. Does anyone know where its at?

I keep coming across equation 16.2 (on page 16-5) which is: Gp= 3.2+L/4.0+(2.7Nped/We)

But you need to know walkway effective width and the number of pedestrains for this equation.

Thanks in advance for your help.

I had the same problem, however after much searching I did find the equation they referenced in one of my old college transpo books. That was the only place I could seem to find it.

-Ray

 

[Road Guy]

I believe chapter 16 is mainly for analyzing pedestrians only, where the minimum green time is something that should be considered for every traffic signal that has ped xing.

I have packed up my HCM but if anyone has the 97 HCM and recalls what chapter 9 is called, it should be in the same chapter name as the 2000 HCM. I would look through the "Signalized Interections" Chapter

 

[DVINNY]

I've had this same problem, and just wrote the Gp=7+(W/4.0)-Y into my notes in case it comes up.

 

[Road Guy]

okay my bad. Ch 16 is Signalized Intersetions, so you would use the new HCM formula 16-2 to find the Gp (NCEES should update their sample exam)

but you would either be given the info or use standard defaults (MUTCD should have crosswalk widths recommendations) but thats a little subjective since every state has their own standards.

I would have both forumulas handy.

 

[DVINNY]

good find my man.

You'd think you were a Road Guy or something. uh.... wait.....

 

[DVINNY]

P.S.

maybe I need to go get more familiar with the HCM than just chapters 20-23

 

[AJK]

P.S.
maybe I need to go get more familiar with the HCM than just chapters 20-23

DVINNY,

I had the same thought about 5 weeks ago, and spent a good week going through other chapeters. There is a lot of information in the HCM, (particularily in the "Methodologies Section") which seems like possible exam material to me.

The way the HCM is set up, you can waste a lot of time paging through it looking for something.

Also you can easily spend a week just on the signalized intersections chapter. This is the area where I am the weakest.

Andrew

 

[bigray76]

DVINNY,
I had the same thought about 5 weeks ago, and spent a good week going through other chapeters. There is a lot of information in the HCM, (particularily in the "Methodologies Section") which seems like possible exam material to me.

The way the HCM is set up, you can waste a lot of time paging through it looking for something.

Also you can easily spend a week just on the signalized intersections chapter. This is the area where I am the weakest.

Andrew

I copied the pages of the chapter worksheets for LOS and put them in my transpo binder. I figured if a LOS type question came up, I could go to the one that is applicable and start to set up my work... granted I will still need to go to the HCM to get all the factors, those pages are tabbed.

-Ray

 

[owillis28]

Does anybody have a current pdf (or scan) of the LOS chart from the HCM they can post?

owillis

 

[DVINNY]

the CERM has it in one of the 70's Chapters. I don't have it with me, I just packed all mine up for the night

 

[DVINNY]

there are ones for Highway, Multilane, even pedestrian and bicycle though

 

[lev280]

NCEES Sample problems have not been updated since the new HCM came out. This problem can ONLY be solved using the old HCM.

I am working The Transportation portion of the NCEES sample exam. I'm having some issues with problem 501, which asks for a minimum green time for a signal given the crosswalk width and some other factors.

The solution references chapter 9 of the 1997 HCM, and give the equation: Gp=7+(W/4.0)-Y

I cannot seem to find this equation in my copy of the 2000 HCM. Does anyone know where its at?

I keep coming across equation 16.2 (on page 16-5) which is: Gp= 3.2+L/4.0+(2.7Nped/We)

But you need to know walkway effective width and the number of pedestrains for this equation.

Thanks in advance for your help.