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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
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    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Research in Progress (RIP)</title>
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      <title>Developing Guidelines for Evaluating Pressure on Existing Culverts under New Embankments with Buried Lightweight Materials when Highway Widening</title>
      <link>https://rip.trb.org/View/1877372</link>
      <description><![CDATA[Existing culverts are often left in place and extended when highways are widened. Many existing reinforced concrete box culverts (RCBCs) were built using stepped construction, with slab thickness decreasing as the embankment height decreases along the culvert. On widening projects, lightweight fill is often used above thinner culvert sections to avoid increasing the net load on culverts. This type of construction has been used with stepped-down culverts on I-75 and I-64 widening projects. The current method of calculating culvert pressures assumes a vertical column of material and has been found through field instrumentation to be conservative for geofoam and non-conservative for foam concrete.]]></description>
      <pubDate>Wed, 08 Sep 2021 11:04:05 GMT</pubDate>
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