Engineering Commons^™

Investigation And Modification Of Single-Post Aluminum Sign Supports For Mash Crashworthiness, Rodrigo Quintero

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Traffic signs are used to display information to drivers and are one of the most commonly encountered roadside structures. Although they are a vital traffic control device, signs can pose a significant safety risk to errant drivers due to their extensive placement and proximity to the roadway. Therefore, traffic signs and their supports must be designed with crashworthiness in mind to reduce the likelihood of injury in the event of a vehicle impact. Prior to 2009, these systems were evaluated using the crash testing criteria found in the National Cooperative Highway Research Program (NCHRP) Report No. 350 [1]. Currently, they …

Crashworthy Perforated Square Steel Tube (Psst) Mailbox Support – Phase I, Robert W. Bielenberg, Cody S. Stolle, Ronald K. Faller

Nebraska Department of Transportation: Research Reports

Federal requirements have made it mandatory that safe mailbox support systems be designed to yield or breakaway whenimpacted by a vehicle. The Nebraska Department of Transportation (NDOT) has previously used a non-proprietary, U-channel post mailbox support that was evaluated at the Midwest Roadside Safety Facility (MwRSF) in the 1980's. NDOT desires that the mailbox support be updated to meet MASH 2016 TL-3 safety performance criteria and be redesigned to use perforated square steel tubing (PSST) for the mailbox support post.

The objective of this research project is to develop a non-proprietary mailbox support using PSST support posts that is MASH …

Development Of A Mash Test Level 4 Open Concrete Bridge Rail, Jacob Delone

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

An open concrete bridge rail was designed and developed according to safety performance guidelines in the American Association of State Highway Transportation Officials (AASHTO) Manual for Assessing Safety Hardware (MASH) for Test Level 4 (TL-4). Systems designed and developed under previous guidance were studied, and their geometric information and full-scale crash testing performance was studied to establish the geometry of the new bridge rail. Yield-Line Theory and the AASHTO Post and Beam design methods were studied, and a modified version of the AASHTO Post and Beam method was utilized to determine the capacity of the new open concrete bridge rail. …

Continued Development Of A Non-Proprietary, High-Tension, Cable End Terminal System, Jennifer D. Schmidt, Robert W. Bielenberg, John D. Reid, Ronald K. Faller

Nebraska Department of Transportation: Research Reports

A non-proprietary, cable guardrail system is currently under development for the Midwest States Pooled Fund Program. A cable guardrail end terminal was necessary to accompany the cable guardrail system. The objective of this research project was to develop design recommendations for the cable end terminal. Bogie testing that was previously completed on a design concept indicated delayed cable release, which was an undesired performance that led to vehicle instabilities. Several design changes were recommended for better end terminal performance and to reflect the changes made to the cable median barrier. An LS-DYNA model of the modified cable end terminal was …

Midwest Guardrail System (Mgs) With An Omitted Post, Jessica L. Lingenfelter, Scott Rosenbaugh, Robert W. Bielenberg, Karla A. Lechtenberg, Ronald K. Faller, John D. Reid

Nebraska Department of Transportation: Research Reports

The objective of this research study was to evaluate the MGS (31” tall W-beam guardrail) with an omitted post according to the safety performance criteria provided in MASH. A single full-scale crash test was conducted with the 2270P pickup truck in accordance with MASH test no. 3-11. The small car test, test no. 3-10, was deemed unnecessary as the pickup truck test would result in higher rail loads, a greater propensity for rail rupture, and a greater risk of failure. The test installation utilized standard 6-ft (1.8-m) long steel guardrail posts with 12-in. (305-mm) deep blockouts. A single post was …

Performance Characteristics Of Posts Embedded In Soil, Brandt M. Humphrey, Karla A. Lechtenberg, John D. Reid, Ronald K. Faller, James C. Holloway

Nebraska Department of Transportation: Research Reports

The primary objective of this research study was to determine the post-soil impact reaction of W6x8.5 (W150x12.6) steel posts and 6-in. x 8-in. (152-mm x 203-mm) Southern Yellow Pine (SYP) posts, specifically along the weak axis. Five bogie tests were conducted on W6x8.5 (W150x12.6) A992 steel posts with a length of 72 in. with embedment depths ranging between of 24 and 40 in. (610 and 1,016 mm). Four bogies tests were conducted on 6-in. x 8-in. (152 mm x 203 mm) SYP posts embedded at depths ranging between 30 and 40 in. (735 and 1,016 mm). The target impact conditions …

Cable-To-Post Attachments For Use In Non-Proprietary High-Tension Cable Median Barrier – Phase Ii, Scott K. Rosenbaugh, Robert W. Bielenberg, Brandt M. Humphrey, Ronald K. Faller, John D. Reid, Karla A. Lechtenberg

Nebraska Department of Transportation: Research Reports

The research objectives reported herein were based on further development of cable-to-post attachment hardware for use in the non-proprietary high-tension cable barrier system. Specifically, this project aimed to develop and evaluate alternative attachment designs for the bolted, tabbed bracket and evaluate the use of a larger diameter, keeper rod for use in the top cable attachment. From a group of over 25 alternative attachment concepts, two tabbed bracket designs were selected for evaluation through dynamic component testing: 1) the lateral shear plate attachment and 2) the drop-in shear plate attachment. The drop-in shear plate concept did not perform as intended, …

Design Of An Improved Post For Use In A Non-Proprietary High-Tension Cable Median Barrier, Robert W. Bielenberg, Ronald K. Faller, Karla A. Lechtenberg, Tyler L. Schmidt, Scott K. Rosenbaugh, John D. Reid, Dean L. Sicking

Nebraska Department of Transportation: Research Reports

The objective of this research study was to develop a revised post section for the non-proprietary high-tension cable median barrier that improved the safety and function of the post by lowering strong-axis forces. A total of twenty dynamic component tests were performed, along with one cable pull test – ten tests with the 7-gauge C-section post, eight with the 10-gauge C-Section posts, and three with the Midwest Weak Post (MWP). The tests were conducted with the posts installed in either a compacted, crushed limestone soil or a rigid sleeve in order to determine the force vs. deflection and energy vs. …

Conceptual Development Of An Impact-Attenuation System For Intersecting Roadways, Joseph G. Putjenter

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Longitudinal barriers are commonly used to shield hazards, including stiff bridge rail ends and slopes. In some locations, a secondary roadway intersects the primary roadway within the guardrail’s length-of-need (LON). Some intersections have as little as 15 ft (4.6 m) between the intersection and beginning of the bridge railing, which require short-radius guardrail systems. No short-radius systems have been tested and approved to current impact safety standards for shielding hazards with these conditions.

Site conditions provided by the Nebraska Department of Roads were used to determine the constraints for a new safety treatment for intersecting roadways and include intersection radii, …

Development Of Socketed Foundations For S3x5.7 Posts, Scott K. Rosenbaugh, Tyler L. Schmidt, Ronald K. Faller, John D. Reid

Nebraska Department of Transportation: Research Reports

The objective of this study was to develop a socketed foundation for use with the S3x5.7 (S76x8.5) weak post. The design focused on cylindrical, reinforced concrete foundations with a steel tube placed in the center for use as the socket. The foundation was to prevent both damage and displacements exceeding 1 in. (25 mm), as measured at groundline, during an impact event. To evaluate various foundation designs, ten dynamic bogie tests were conducted over three separate rounds of testing. Round 1 was conducted in a weak, sandy soil; Round 2 was conducted in a strong, stiff soil; and Round 3 …

Development Of A Mash Tl-3 Transition Between Guardrail And Portable Concrete Barriers, David A. Gutierrez

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Often, road construction causes the need to create a work zone. In these scenarios, portable concrete barriers (PCBs) are typically installed to shield workers and equipment from errant vehicles as well as prevent motorists from striking other roadside hazards. For an existing W-beam guardrail system installed adjacent to the roadway and near the work zone, guardrail sections are removed in order to place the portable concrete barrier system. The focus of this research study was to develop a proper stiffness transition between W-beam guardrail and portable concrete barrier systems. This research effort was accomplished through development and refinement of design …

Cable Median Barrier Failure Analysis And Prevention, Dean L. Sicking, Cody S. Stolle

Mid-America Transportation Center: Final Reports and Technical Briefs

Cross-median crashes have been identified as one of the highest injury or fatality risk crash types. Although crossmedian crashes account for only 2% to 5% of all median crash events, they are disproportionately represented in the number and frequency of fatalities on interstate roadways. Many states have utilized cable median barriers to reduce the risk of cross-median crashes, frequently with great success. However, cable median barriers are also fixed obstacles to errant vehicles. Cable median barriers can place occupants at increased risk of severe injury or fatality if the barrier fails to adequately contain and redirect errant vehicles, resulting in …

Development Of Advanced Finite Element Material Models For Cable Barrier Wire Rope, John D. Reid, Karla A. Lechtenberg, Cody S. Stolle

Mid-America Transportation Center: Final Reports and Technical Briefs

An improved LS-DYNA model of ¾-in. (19-mm) diameter 3x7 wire rope commonly used in roadside cable guardrail installations has been developed. A Belytschko-Schwer beam element was selected along with material *MAT_166. Numerical noise was reduced using part stiffness damping with a coefficient of 2%, and frequency range damping with a coefficient of 12%. The optimum element length based on timestep, accuracy, and computational cost was determined to be between 0.4 and 0.8 in. (10-20 mm). Dynamic component tests were conducted on wire rope to determine material properties. These tests were simulated and the results compared to the physical tests. The …