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Low Tension Cable End Terminal Details

Question
State NE
Description Text

We are drawing up the cable guardrail end treatment from reports TRP-03-155-05 & TRP-03-192-08 & need a little help with the details. Please see standard sheet attached.

 

For A (below) " will you agree to allow the exterior gussets be brought in, to 3/8" from the outside edges?

            This is where we believe the 3/8" weld will work.

I assume all gusset plates are welded inside & out, or is a weld on the inside only.

 

For B (below) - will the welds be allowed for the 1 ¼" across the release lever plate connecting to the base plate?

 

The bracket plate or cable plate is the only 3/8" plate with the rest being ½". What is the reason for this?

Can it be changed to ½" so all plates in this assembly are the same?

 

Is there a reason for the holes in the triangle release lever plate gussets?

We found a bolt in these holes of report TRP-03-192-08 Figure A-2 Cable Terminal Detail, sheet 2 of 12.

 

Should there be a light weight tie down cable to keep the cable release lever from flying somewhere it shouldn't go?

            This was used in the testing on the high tension cable.

Keywords
  • End Treatments & Crash Cushions
  • Guardrail
Other Keywords none
Date December 10, 2009
Attachment sheet 5 standards.jpeg


Response
Response

I have responded to your questions below in red.

 

For A (below) " will you agree to allow the exterior gussets be brought in, to 3/8" from the outside edges?  

-       We believe there is no problem with moving the gussets in 1/8" to allow for the 3/8" weld. This is an error in our CAD.

            This is where we believe the 3/8" weld will work.

I assume all gusset plates are welded inside & out, or is a weld on the inside only.

-       Gussets are to be welded inside and out as well as the ends (all the way around).

 

For B (below) - will the welds be allowed for the 1 ¼" across the release lever plate connecting to the base plate?

-       This is another error in our CAD. The weld callout should read " 1" @ 4 ¼" C-C". This will center the weld correctly on the release lever plate.

 

The bracket plate or cable plate is the only 3/8" plate with the rest being ½". What is the reason for this?

Can it be changed to ½" so all plates in this assembly are the same?

-       We have no problem with using ½" plate for the cable plate. It should not adversely affect the design.

 

Is there a reason for the holes in the triangle release lever plate gussets?

-       The holes in the plate are for a bolt to connect a retention cable for the release lever. The rationale behind this is detailed in TRP-03-131-08.

-       The design calls for a 5/8" Grade 5 Hex Bolt.

We found a bolt in these holes of report TRP-03-192-08 Figure A-2 Cable Terminal Detail, sheet 2 of 12.

 

Should there be a light weight tie down cable to keep the cable release lever from flying somewhere it shouldn't go?

            This was used in the testing on the high tension cable.

-       Yes, there should be a retention cable. It should be ¼" diameter 7x19 aircraft cable. The cable should be 36" long and formed into a loop  with 1" cable clips. See attached photos.

 

-       One other note. The CAD details show the use of 2 washers on the end fittings that connect to the cable plate. This is incorrect. We used a minimum of three washers on the end fittings. As an alternative, we designed 3"x2.125"x0.5" plate washers for the high tension design. These would be acceptable as well.

 What is the length of need for the new cable end treatment system?

 

** Test no. CT-1 was conducted on a low-tension, three-cable barrier system according to test designation no. 3-35 of NCHRP Report No. 350. The test was successfully performed as a Length-of-Need (LON) evaluation at the target conditions of 100 kph and 20 deg. The test occurred at post no. 3 or approximately 15 ft from the upstream end of the barrier system. Based on the results obtained from the 2000P test (test no. CT-1), the length of need for the low-tension, three-cable barrier has been determined to be 15 ft.

 

Date December 15, 2009
Attachment DSC_7765.JPG
Attachment DSC_7763.JPG


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