Please help me solve a DOE problem - New Minitab User

Y

yasharif

Dear Miner
I have looked into the graphs you have send it to me.

Can we have 3 separate equations for 3 different materials: paint, thermo and polyurea?

So that we can show that this material still has some RL value left at the end of 10th year other than two materials and make a cost analysis and show that this material lasts long and is cost effective.

Is there any way we can find 3 equations for these 3 materials to find the Final RL value at the end of 10th year?

Example: FInal RL= Initial RL - Time(month)* Coefficient- ADT* coeffficient (for white skip/ white edge/ yellow edge/ yellow centrline)


Thank you.
I really appreciate your time and help.

Regards
Sharif
 

Miner

Forum Moderator
Leader
Admin
Yes that is possible. I have to do a lot of manipulation to get the data into the correct format first.
 

Miner

Forum Moderator
Leader
Admin
Attached are the equations that you requested.
 

Attachments

  • dataset.xlsx
    243.5 KB · Views: 87
Y

yasharif

Thanks Miner, I appreciate.
I am going to look into it right now..thanks..
Regards
Sharif
 
Y

yasharif

Dear Miner
Thank you very much for your effort.
I just tried the equations right now with some of the data.
Age of material we have taken 10 years that means 120 months. and Lowest ADT we have taken 15000 and the highest ADT 130000.
But for WHITE SKIP equation: for ADT 15000 and age/time 120 years
The paint and polyurea equation comes up with negative number and thermo comes with a positive number.

Infact in reality Paint lasts for very short term like atmost 2 years.

Polyurea is supposed to last more than paint and thermo..

But I used the equation and found it is showing thermo lasting longer than polyurea.

And in polyurea equation I see the ADT coefficient comes up with a +ve term.

Can you light me little more on the equations?

I really appreciate your time.

Thank you so much.

Regards
Sharif
 

Miner

Forum Moderator
Leader
Admin
Good questions. I'll check into the +ve issue.

Do you have a specification for the minimum RL? you can substitute that into the equation and solve for the # months till you reach wearout.

Regarding the negative values at a specified time. A regression equation cannot distinguish between a ratio scale (stops at zero) and an interval scale (goes negative). The user must understand that a negative number is not feasible and recode them as zero.

Regarding the longer lasting material, Thermo showed up best in the graphs that I sent.
 
Y

yasharif

Thanks Miner for your quick response.

Yes you are absolutely right. I took the negative numbers to be zero.

For the 3 materials we are using we have a minimum retroreflective number requirement at the beginning of layout of the material on the roadway.

For paint at initial layout it has to have atleast : White: 225 RL, Yellow : 200 RL

Otherwise the contractor is going to be asked to repaint the roadway again to satisfy the minimum requirement.

As well for other two materials:

Thermo and Polyurea: White : 375 RL and Yellow: 250 RL.

But the Minimum for the materials after the long life of the material has not been fixed yet. AASHTO is trying to keep it 100 RL for all 3 materials and some other organizations 75.

Thank you very much.

I really appreciate your valuable time.

Regards
Sharif
 

Miner

Forum Moderator
Leader
Admin
I reviewed the regression graphically, and the +ve is correct. I can think of two possibilities that might explain this.
  • Is the road surface (i.e., substrate) identical for low/high ADT road? A different substrate could interact with the material and bias the results for high ADT roads.
  • If the RL is total unacceptable, is the reading still recorded or is it omitted? Censoring in this manner would bias the results upward, favoring the longest lived more.

Added: I think there may be more variables that were not included in your dataset that are unique to high ADT. The difference is primarily the highest ADT samples. These variables might include the type of traffic, snow removal/prevention practices, type of pavement, age of pavement, etc.
 
Last edited:
Y

yasharif

Thanks for quick reply.

1. So far I know all the roads are BST road (bituminous surface treatment).
2. The readings are not omitted. Whatever the reading was found from the instrument were noted down for database.

Thanks.

Regards
Sharif
 
Top Bottom