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As we discussed please see the
As I eluded to
With an Lg of
For the Madison
I’m out of the
Image 806 is where we plan to
I would much prefer starting the end terminal from the
The trailing back around the radius of the side road
I'm sure you're waiting on an answer, so I'll talk with
The guardrail layout is a long section that extends from
These pictures show the last two sections extending the
|Date||August 7, 2015|
A few years ago, MwRSF conducted a research study for the Wisconsin DOT. This effort explored the performance of W-beam short-radius guardrail systems under TL-2 impact conditions with larger radii. See the link to access a copy of the report. Also, note the Chapters & Sections that are recommended for reading.
See page 199 or PDF page 213!
See Chapter 12 – page 205 – PDF page 219!
See Chapter 13 – page 223 – PDF page 237!
See Chapter 14 – page 227 – PDF page 241!
From this simulation effort, it was determined that rail heights greater than 27 in. and up to 31 in. would improve barrier performance for pickup truck impacts. Although no small car simulations were performed, there is concern that a 31 in. rail height could accentuate small car underride. As such, it was believed that a 29 in. rail height may still provide improved performance for pickup truck impacts but reduce concerns for small car underride. In the absence of an actual crash testing program at TL-2, MwRSF personnel would lean toward the use of a 29 in. rail height versus a 27 in. rail height based on the best available information and results from this study. Of course, the only true evaluation of safety performance would be through full-scale crash testing.
Second, the study noted that blockouts on posts around the radius contributed to improved vehicle capture by better maintaining adequate rail height. Blockouts also showed an ability to reduce vehicle to post contact. Further, CRTs were simulated around the nose through the tangent sections. As such, it would be recommended to maintain the CRTs throughout the entire curve and into tangent for any larger radius system that is implemented.
It should also be noted that the simulation effort was performed with level terrain behind the barrier system. Your real-world scenario will likely feature a gradual slope behind the barrier system for some distance, followed by a steeper slope. Barrier performance can be greatly affected by the presence of various slopes behind the actual barrier. Thus, it is recommended to provide a gentle slope behind the barrier using as much lateral distance as feasibly possible.
Again, these thoughts are provided based on our best available information as well as the research findings from the recent simulation effort. If you have any questions regarding this information, please feel free to contact either myself or my included colleagues at your convenience. Thanks!
|Date||August 7, 2015|
130 Whittier Research Center
2200 Vine Street
Lincoln, NE 68583-0853
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