PHF

[305Gurl]

I have a project that I am working on. I was given the counts for a particular intersection, but for the life of me I cannot determine how the PHF of 0.92 was determined. I know it is the Peak hour volume/ Peak 15min vol. The most I got was 0.88 found by the following calculation:

The peak hour volume is found between the hour of 7:45 am and 8: 45 am in the westbound direction. This total volume of 1633 is the peak hour volume. This is the sum of the left, through and right turns between 7:45 and 8:45 am, and is the highest 4 intervals of 15 minutes volume. Then PHF = 1633/ (4 * 465)= 0.88. This 465 was found from the highest 15 minute within the peak hour volume (14+444+7).

Could some please tell me what I have done incorrect of was the PHF provided to me incorrect. See counts attached for the intersection.

Thanks a bunch!

 

[John QPE]

From what you gave, I'm getting 0.88 as well .... I did not go through the data, I'm just going off what you provided in the statement.

 

[RIP - VTEnviro]

I'm not familiar with the PHF method, but am well versed in the GFY system.

 

[PSU09Vet]

Traffic totally isn't my strength but I'll take a stab at it ...

0.92 if for the entire intersection. The peak 15 minute period for all approaches is the 8:15 time.

All approaches to the intersection (if I added correctly) are 3,455 in that 60-minute period, the peak 15-minute number of approaches are 939.

(3,455)/(4x939) = 0.91986...

So IMHO the 0.92 is for the intersection as a whole.

Please anyone correct me or enlighten me if I misunderstood that. Again hoping my Achilles Heel (traffic) didn't do enough damage to my exam score ... :mellow:

 

[PSU09Vet]

I'm not familiar with the PHF method, but am well versed in the GFY system.

I assume this is a close spinoff of the GFYS method? It's what I tend to apply to this subject. :afro:

 

[ptatohed]

I have a project that I am working on. I was given the counts for a particular intersection, but for the life of me I cannot determine how the PHF of 0.92 was determined. I know it is the Peak hour volume/ Peak 15min vol. The most I got was 0.88 found by the following calculation:

The peak hour volume is found between the hour of 7:45 am and 8: 45 am in the westbound direction. This total volume of 1633 is the peak hour volume. This is the sum of the left, through and right turns between 7:45 and 8:45 am, and is the highest 4 intervals of 15 minutes volume. Then PHF = 1633/ (4 * 465)= 0.88. This 465 was found from the highest 15 minute within the peak hour volume (14+444+7).

Could some please tell me what I have done incorrect of was the PHF provided to me incorrect. See counts attached for the intersection.

Thanks a bunch!

305,

The formula for PHF is PHF = Vvph / (4 x V15 min peak)

I am assuming that the spreadsheet is correct and that 7:45 to 8:45 is the peak hour (it seems like it is)

We get Vvph by adding up all of the vehicle movements within that 60 minute period. This is shown as 3,455 under the Total Pk Hr Volume (I double checked and it is correct). Also, we can see by the diagram 202+11+82+17+1575+41+57+1306+34+48+5+77=3455

What isn't shown on the spreadsheet is V15. Doing some quick calcs to find V15:

V8:00-8:15 = 795

V8:15-8:30 = 939 <---- Use

V8:30-8:45 = 503

So, V15 min pk = 939

PHF = 3455 / (4 x 939) = 0.9199

 

[RIP - VTEnviro]

I'm not familiar with the PHF method, but am well versed in the GFY system.

I assume this is a close spinoff of the GFYS method? It's what I tend to apply to this subject. :afro:

Very close corollary. Same method of thinking.

 

[PSU09Vet]

I'm not familiar with the PHF method, but am well versed in the GFY system.

I assume this is a close spinoff of the GFYS method? It's what I tend to apply to this subject. :afro:

Very close corollary. Same method of thinking.

I wanted to be sure. :B

 

[305Gurl]

Ptatohed,

Got it! Thanks again for the detailed explanation for this problem. Appreciated. I somehow got the numbers jumbled up and could not find the correct answers. Now I know for sure that we can trust this new consultant we recently hired on board. Jut wanted to verified.

I have a project that I am working on. I was given the counts for a particular intersection, but for the life of me I cannot determine how the PHF of 0.92 was determined. I know it is the Peak hour volume/ Peak 15min vol. The most I got was 0.88 found by the following calculation:

The peak hour volume is found between the hour of 7:45 am and 8: 45 am in the westbound direction. This total volume of 1633 is the peak hour volume. This is the sum of the left, through and right turns between 7:45 and 8:45 am, and is the highest 4 intervals of 15 minutes volume. Then PHF = 1633/ (4 * 465)= 0.88. This 465 was found from the highest 15 minute within the peak hour volume (14+444+7).

Could some please tell me what I have done incorrect of was the PHF provided to me incorrect. See counts attached for the intersection.

Thanks a bunch!

305,

The formula for PHF is PHF = Vvph / (4 x V15 min peak)

I am assuming that the spreadsheet is correct and that 7:45 to 8:45 is the peak hour (it seems like it is)

We get Vvph by adding up all of the vehicle movements within that 60 minute period. This is shown as 3,455 under the Total Pk Hr Volume (I double checked and it is correct). Also, we can see by the diagram 202+11+82+17+1575+41+57+1306+34+48+5+77=3455

What isn't shown on the spreadsheet is V15. Doing some quick calcs to find V15:

V8:00-8:15 = 795

V8:15-8:30 = 939 <---- Use

V8:30-8:45 = 503

So, V15 min pk = 939

PHF = 3455 / (4 x 939) = 0.9199

 

[ptatohed]

You're welcome 305. My pleasure.

For some reason, I totally missed PSU's post #4 yesterday. I only saw his post #5! I probably wouldn't have added post #6 had I seen that PSU already demonstrated how to derive the PHF = 0.92. Good job PSU.

 

[PSU09Vet]

You're welcome 305. My pleasure.

For some reason, I totally missed PSU's post #4 yesterday. I only saw his post #5! I probably wouldn't have added post #6 had I seen that PSU already demonstrated how to derive the PHF = 0.92. Good job PSU.

No worries, I raced through it without showing my work like you did. Plus this is not the topic I'm confident in anyway. Always better to have corroboration! I used it as a way to check my own understanding. :B