Friday, January 7, 2011

LRFR Guidelines Revision #1 Clarifications

After a few questions from multiple consultants, RIDOT sent back responses to answer our questions.

These are our responses to your questions for clarification: (AECOM)


1. Page 21 – Load Rating Report: there is a statement in bold at the bottom regarding the color of the cover that states “… is any rating is…” My interpretation of this statement is that it is inclusive of the BP and OP vehicles. This would be a change from what we’ve been told previously (i.e. color of the cover determined only by the “legal” load vehicles)

Response: The color of the cover is not determined only by the legal load vehicles but by any rating and is independent of the controlling limit state and is strictly based on the controlling rating factors regardless of what controls the posting.

2. Page 22 – Load Rating Report Layout Table: Item 4 says “PE Stamp to be included” however there is no space on the reference sheet 24 for the stamp. Is the stamp required or just the PE number?

Response: The PE number is sufficient.

3. Page 22 – Load Rating Report Layout Table: Item 14 says “…and the written agreement of the independent reviewer.” Where can this written agreement be found?

Response: The independent reviewer should agree that the computations (Index, sketches, hand calculations..) are satisfactory in writing. Note, his signatures or initials on the computation sheets are considered a written agreement.

4. Page 24 – Summary of Bridge Rating: The new table now has a RL (TONS) input required for the HL-93 at Inv and Oper level where previously these were N/A and only rating factors were supplied. There has been some debate over what the correct vehicle weight is for the HL-93 notional load. What is the weight we should be using for this vehicle to get the rating loads (tons)?

Response: The rating of HL-93 in the new table is represented by an RF only for inventory and operating level and RL (Tons) are not applicable here since HL-93 is only a notional load.

5. There are a few times throughout the manual where the statement “…the initials of the reviewer shall be placed on every sheet of the calculations.” Are electronic initials sufficient for “hand-calcs” using programs such as MathCAD or are wet initials required?

Response: Any kind of initials will do.

6. Regarding the new vehicles I would like to make sure that what I’ve concluded from the new guidelines is correct:
a. RI-BP3 is a new vehicle
b. RI-BP4 was previously RI-OP2
c. RI-OP2 was previously RI-OP3
d. RI-OP2 was previously RI-OP4

Response: All the above correct except for d.
d. RI-OP3 was previously RI-OP4

If you have any further question, let us know.
Here are the answers to your questions: (AI)


1) On Page 6 Table #1 the HL-93 and Specialized Hauling Vehicles (SU4,SU5,SU6 & SU7) are listed as AASHTO Legal loads. Is there any reason?

Answer 1: The Specialized Hauling Vehicles are considered part of the legal loads per the MBE and FHWA regulations.

2) Response: The color of the cover is not determined only by the legal load vehicles but by any rating and is independent of the controlling limit state and is strictly based on the controlling rating factors regardless of what controls the posting.

Does this include also HL-93 vehicle?

Answer 2: The HL-93 is a notional load and not an actual vehicle, and should not be considered in deciding the color of the cover.

3) Could you clarify which legal loads are we going to use for posting analysis?

Answer3: Page 24 Rating Table includes Posting Column, the posting values should be calculated for every single vehicles listed in that table except for

HL-93. RIDOT will decide later how the posting signs will be carried out across the state.
After all of this we still noticed one change that the new RI-BP4 is not the same as the previous RI-OP2 with changes in the spacing between the last two axles previously 4'-6" and now 4'-3".
 
You are right the RI-BP4 was previously RI-OP2 and the rear axle spacing should be 4’-6”. It was a typing error in our latest manual and we will correct.

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