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Temporary Concrete Barrier LON

Question
State	KS
Description Text	Do you have any guidance on appropriate LON for temp. concrete safety barrier. We typically use the RDG guidelines which seems excessive. Would this be a good candidate for a pooled fund project?

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Date March 9, 2005
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Response
Response (active)	There are really two related issues at work when we look at the LON for PCB installations. First, there is the amount of barrier required to effectively shield the hazard. This is specified by the RDG. Dr. Sicking came up with some more reasonable guidelines for LON in the past and we feel very comfortable with these as well. The second issue deals with the beginning of the LON for PCB's. Because PCB's do not have a standard end termination with anchorage, it is difficult to determine where safe redirection of impacting vehicles begins. However, we can make some suggestions based on past testing and experience. FLDOT requested recommendations on this issue earlier this year and I have copied our response to them below. Basically, these recommendations layout the number of barriers needed to effectively redirect a vehicle impacting at the beginning of the LON. Therefore, the answer to you LON for PCB questions is that the basic LON can be determined by either the RDG or Dr. Sicking's LON recommendations. Then it becomes necessary to install a number of barriers upstream of the beginning of LON in order to insure effective redirection along the entire LON. Our best recommendations for these upstream barriers are given in the email to FLDOT below. This has been a big issue for a while now and there is no well researched effective answer. These issues could possibly be resolved through further research and testing to determine a more exact number of barriers for both the LON and the barriers upstream of the LON. The best solution for this problem would be the development of an effective anchorage and end termination for PCB's. This would provide safe termination of the barriers and would allow us to more accurately determine the LON in a manner similar to the guardrail recommendations. I do believe that this would make an excellent pooled fund project. It is a question that needs to be answered for many state DOT installations. Dean has suggested this as a possible topic for this years pooled fund meeting. I would recommend discussing this issue with some of the other states to get their support. I do know that FLDOT has expressed a great deal of interest in this topic and might be willing to contribute if necessary.

Response

Response
(active)

There are really two related issues at work when we look at the LON for PCB installations. First, there is the amount of barrier required to effectively shield the hazard. This is specified by the RDG. Dr. Sicking came up with some more reasonable guidelines for LON in the past and we feel very comfortable with these as well. The second issue deals with the beginning of the LON for PCB's. Because PCB's do not have a standard end termination with anchorage, it is difficult to determine where safe redirection of impacting vehicles begins. However, we can make some suggestions based on past testing and experience. FLDOT requested recommendations on this issue earlier this year and I have copied our response to them below. Basically, these recommendations layout the number of barriers needed to effectively redirect a vehicle impacting at the beginning of the LON.

Therefore, the answer to you LON for PCB questions is that the basic LON can be determined by either the RDG or Dr. Sicking's LON recommendations. Then it becomes necessary to install a number of barriers upstream of the beginning of LON in order to insure effective redirection along the entire LON. Our best recommendations for these upstream barriers are given in the email to FLDOT below.

This has been a big issue for a while now and there is no well researched effective answer. These issues could possibly be resolved through further research and testing to determine a more exact number of barriers for both the LON and the barriers upstream of the LON. The best solution for this problem would be the development of an effective anchorage and end termination for PCB's. This would provide safe termination of the barriers and would allow us to more accurately determine the LON in a manner similar to the guardrail recommendations.

I do believe that this would make an excellent pooled fund project. It is a question that needs to be answered for many state DOT installations. Dean has suggested this as a possible topic for this years pooled fund meeting. I would recommend discussing this issue with some of the other states to get their support. I do know that FLDOT has expressed a great deal of interest in this topic and might be willing to contribute if necessary.

Date March 15, 2005
Previous Views (123) Favorites (0)