Engineering Commons^™

Inventory, Operations, And Safety At Free Right-Turn Ramps, Aemal Khattak, Jonathon Camezind, Mm Shakui Haque

Nebraska Department of Transportation: Research Reports

This research focused on traffic safety and operational performance of rural, minor approach stop-controlled intersections with free right-turn (FRT) ramps. The objectives of the research were to:

• Create a statewide inventory of rural FRT ramp intersections and provide to the Nebraska Department of Transportation (NDOT),
• Using NDOT 10-year crash data, conduct statistical safety analysis of rural FRT intersections extending ¼-mile in each direction from the intersection,
• Study vehicular operations at rural intersections with and without FRT ramps including a comparison of vehicular conflicts, and
• Develop guidelines for operations and safety tradeoffs to assist with NDOT projects on maintaining similar locations, …

Research On School Zone Safety, Aemal Khattak, Yashu Kang

Nebraska Department of Transportation: Research Reports

This research investigated different aspects of school zone safety including the effects of speed differentials on drivers’ speeds in active school zones, the effects of school and surrounding characteristics on drivers’ speeds in active school zones, and the safety benefits and costs associated with active school zones. The research team identified 18 schools in Nebraska for data collection that consisted of drivers’ speed data, school and surrounding characteristics, and 2014-2018 reported crash data. The 18 schools were categorized by the school zone speed limit differentials: 35 to 25 mph, 40 to 25 mph, 30 to 25 mph, and 35 to …

34-Inch Tall Three Beam Transition To Concrete Buttress, Scott Rosenbaugh, Wyatt Fallet, Ronald K. Faller, Robert W. Bielenberg, Jennifer Schmidt

Nebraska Department of Transportation: Research Reports

Roadway resurfacing and overlay projects effectively reduce the height of roadside barriers placed adjacent to the roadway, which can negatively affect their crashworthiness. More recently, bridge rails and concrete barriers have been installed with slightly increased heights to account for future overlays. However, adjacent guardrails and approach transitions have not yet been modified to account for overlays. The objective of this project was to develop an increased-height, approach guardrail transition (AGT) to be crashworthy both before and after roadway overlays of up to 3 in. (76 mm).

A 34-in. (864-mm) tall, thrie beam transition was designed such that the system …

Phase Ii Evaluation Of Floor Pan Tearing For Cable Barrier Systems, Dylan T. Meyer, Mojdeh Asadollahi Pajouh, Karla A. Lechtenberg, Ronald K. Faller, Robert W. Bielenberg, James C. Holloway

Nebraska Department of Transportation: Research Reports

The objective of this research effort was to mitigate the potential for floor pan tearing and penetration into the occupant compartment by modifying the posts utilized in a prototype cable barrier system. A series of dynamic component tests were conducted on the modified Midwest Weak Post (MWP). A bogie vehicle was equipped with a simulated floor pan designed to replicate the height, thickness, and strength of the floor pan of a Kia Rio. Two methods of post modification were investigated, including edge protection on the top of the MWP as well as weakening of the MWP at the ground line. …

Mash Test No. 3-10 Of A Non-Proprietary, High-Tension, Cable Median Barrier For Use In 6h:1v V-Ditch (Test No. Mwp-9), Mojdeh Asadollahi Pajouh, Karla A. Lechtenberg, Ronald K. Faller, James C. Holloway, Robert W. Bielenberg, Scott K. Rosenbaugh

Nebraska Department of Transportation: Research Reports

The Midwest Pooled Fund Program has been developing a prototype design for a non-proprietary, high-tension, cable median barrier for use in a 6H:1V median V-ditch. This system incorporates four evenly spaced cables, Midwest Weak Posts (MWPs) spaced at 8 to 16 ft (2.4 to 4.9 m) intervals, and a bolted, tabbed bracket to attach the cables to each post. Full-scale crash testing was needed to evaluate the barrier’s safety performance. According to the Manual for Assessing Safety Hardware 2016 (MASH) testing matrix for cable barriers installed within a 6H:1V median V-ditch, a series of eight full-scale crash tests are required …

Effectiveness Of Chain Link Turtle Fence And Culverts In Reducing Turtle Mortality And Providing Connectivity Along U.S. Hwy 83, Valentine National Wildlife Refuge, Nebraska, Usa, Marcel P. Huijser, Kari E. Gunson, Elizabeth R. Fairbank

Nebraska Department of Transportation: Research Reports

We evaluated the effectiveness of existing turtle fences through collecting and analyzing turtle mortality data along U.S. Hwy 83, in and around Valentine National Wildlife Refuge, Nebraska, USA. We also investigated the level of connectivity for turtles provided through the culverts that were originally designed to pass water through a capture-mark-recapture experiment. While fenced valley sections had 33.1% fewer turtle observations than unfenced valley sections, the difference was not significant. However, we think that the effectiveness of the fence can be improved through fence repairs, other modifications of the fences, vegetation maintenance, and extending the length of the fences. Four …

Increased Span Length For The Mgs Long-Span Guardrail System Part Iii: Failure Analysis, Sagheer A. Ranjha, Robert W. Bielenberg, John D. Reid, Ronald K. Faller

Nebraska Department of Transportation: Research Reports

The objective of this research study was to review and analyze the system failure observed during crash testing of an increased span length for the MGS long-span guardrail system in test no. MGSLS-2. Test no. MGSLS-2 was a full-scale crash test conducted on the MGS long-span guardrail with a span length of 311⁄4 ft (9.5 m). This test utilized universal breakaway steel posts (UBSPs) adjacent to the long span in lieu of the controlled release terminal (CRT) wood posts used in previous long span systems.

An engineering analysis was undertaken to review the downstream end anchorage failure observed in test …

Evaluation Of Floorpan Tearing And Cable Splices For Cable Barrier Systems, Scott K. Rosenbaugh, Jason A. Hartwell, Robert W. Bielenberg, Ronald K. Faller, James C. Holloway, Karla A. Lechtenberg

Nebraska Department of Transportation: Research Reports

This research effort consisted of two objectives related to components of a prototype cable barrier system. The first objective was to mitigate the potential for vehicle floorpan tearing by modifying the cable guardrail posts. A bogie vehicle was equipped with a simulated floorpan designed to replicate the height, thickness, and strength of the floorpan of a Kia Rio vehicle. Baseline testing demonstrated that the top of the Midwest Weak Post (MWP) would contact, and crease the simulated floorpan, which matched the damage observed in actual full-scale vehicle crash tests. Once the test setup provided the desired results, various post configurations …

Length Of Need And Minimum System Length For F-Shape Portable Concrete Barrier, Robert W. Bielenberg, Dylan T. Meyer, Ronald K. Faller, John D. Reid

Nebraska Department of Transportation: Research Reports

Portable concrete barrier (PCB) systems are often used to redirect errant vehicles through a combination of inertial resistance, lateral friction loads, and tensile loads developed from the mass and friction of the barrier segments. State departments of transportation (DOTs) and other end users may wish to utilize minimal length PCB installations to shield a hazard or work zone or limit the number of barriers required on the upstream and downstream ends to reduce overall system length. However, concerns with the performance of shorter PCB installations include increased lateral deflections and working widths and barrier pocketing. Additionally, no impact testing has …

Testing And Evaluation Of Mash Tl-3 Transition Between Guardrail And Portable Concrete Barriers, Robert W. Bielenberg, Jessica L. Lingenfelter, Justine E. Kohtz, Ronald K. Faller, John D. Reid

Nebraska Department of Transportation: Research Reports

Three full-scale vehicle crash tests were conducted according to the Manual for Assessing Safety Hardware (MASH) Test Level 3 (TL-3) safety performance criteria on a transition between the Midwest Guardrail System (MGS) and a portable concrete barrier (PCB) system. The transition system utilized for test nos. MGSPCB-1 through MGSPCB-3 consisted of a standard MGS that overlapped a series of F- shape PCB segments that approached the MGS at a 15H:1V flare. In the overlapped portion of the barrier systems, uniquely-designed blockout holders and a specialized W-beam end shoe mounting bracket were used to connect the systems.

In test no. MGSPCB-1, …

Increased Span Length For The Mgs Long-Span Guardrail System Part Ii: Full-Scale Crash Testing, Dylan T. Meyer, John D. Reid, Karla A. Lechtenberg, Robert W. Bielenberg, Ronald K. Faller

Nebraska Department of Transportation: Research Reports

The objective of this research study was to design and evaluate the MGS long-span design for use with unsupported spans greater than 25 ft (7.6 m). Two full-scale crash tests were conducted to evaluate the MGS long-span system with increased span lengths and the use of UBSP posts adjacent to the long span. Both tests were conducted according to the TL- 3 criteria outlined in MASH. Both test nos. MGSLS-1 and MGSLS-2 were conducted with the 2270P vehicle impacting their respective critical impact points at a speed of 62 mph (100 km/h) and an angle of 25 degrees. Test no. …

Ls-Dyna® Modeling Enhancement Support, John D. Reid, Robert W. Bielenberg, Chaz Ginger

Nebraska Department of Transportation: Research Reports

The Pooled Fund Program member states provided funding for LS-DYNA modeling enhancements in Years 17 thru 22 (2006-2011), with a project period of 2006-2016. This report documents many of the modeling issues addressed throughout the project period. The funding has been effectively utilized to advance the current state-of-the-art for computer simulation and has provided the following benefits for the entire industry: (1) improved roadside safety hardware, (2) reduced development time and cost, (3) improved understanding of the behavior of roadside safety features, especially for impacts outside of normal crash test conditions, (4) improved LS-DYNA modeling techniques and procedures, and (5) …

Mash Tl-4 Crash Testing And Evaluation Of The Restore Barrier, Jennifer D. Schmidt, Tyler L. Schmidt, Ronald K. Faller, Robert W. Bielenberg, John D. Reid, James C. Holloway, Karla A. Lechtenberg

Nebraska Department of Transportation: Research Reports

Three full-scale vehicle crash tests were conducted according to the MASH Test Level 4 (TL-4) safety performance criteria on a restorable and reusable energy-absorbing roadside/median barrier, designated the RESTORE barrier. The system utilized for test nos. SFH-1 through SFH-3 was 240 ft (73.2 m) long with a nominal height of 38⅝ in. (981 mm). The barrier consisted of an upper steel tube rail attached to the top of 20-ft (6.1-m) long x 22.-in. (565-mm) wide precast concrete beams connected with wedge-shaped joints and supported by 11⅝-in. (295-mm) tall rubber posts and steel skids.

In test no. SFH-1, a 5,021-lb (2,277-kg) …

Conceptual Development Of An Impact-Attenuation System For Intersecting Roadways, Joseph G. Putjenter, Robert W. Bielenberg, Ronald K. Faller, John D. Reid

Nebraska Department of Transportation: Research Reports

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 may have as little as 15 ft (4.6 m) between the intersection and beginning of the bridge railing, which require short-radius guardrail systems. One short-radius guardrail system has passed several crash tests under AASHTO Manual for Assessing Safety Hardware (MASH) standards.

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, …

Mgs Dynamic Deflections And Working Widths At Lower Speeds, Nicholas A. Weiland, Cody S. Stolle, John D. Reid, Ronald K. Faller, Robert W. Bielenberg, Karla A. Lechtenberg

Nebraska Department of Transportation: Research Reports

The Midwest Guardrail System (MGS) has been full-scale crash tested in many configurations, including installations adjacent to slopes, with different types of wood posts, with and without blockouts, for culvert and bridge applications, and at high flare rates. Although the performance of the MGS and the dynamic deflection and working width of the barrier have been examined, little is known about the dynamic deflection and working width of the MGS when impacted at lower speeds. The MGS is a relatively low-cost barrier, and the Test Level 3 (TL-3) version could be installed for TL-2 and TL-1 applications. The barrier is …

Investigation Of Rural/Suburban High-Speed Multilane Roundabouts, Aemal Khattak, Eric Thompson, Shanshan Zhao

Nebraska Department of Transportation: Research Reports

This research was focused on two issues related to multilane roundabouts on high-speed highways (speed limit 45 mph or greater) in rural and suburban areas. The first was the tradeoff between converting a traditional stop-controlled or signalized intersection to a multilane roundabout while the second was the safety of newly constructed high-speed multilane roundabouts in rural and suburban areas. The research team reviewed information from diverse published documents and conducted a survey of state and local transportation agencies. Crash data on multilane rural roundabouts were not available for this research. Therefore, the research team relied on crash and other data …

Safety Performance Evaluation Of The Non-Blocked Midwest Guardrail System, Kevin D Schrum, Karla A. Lechtenberg, Robert W. Bielenberg, Scott K. Rosenbaugh, Ronald K. Faller, John D. Reid

Nebraska Department of Transportation: Research Reports

No abstract provided.

Safety Improvements At Highway-Railroad Crossing For Pedestrians And Bicyclists And The Assessment Of Long-Term Effects Of Centerline Curbing, Aemal Khattak, Zheng Luo

Nebraska Department of Transportation: Research Reports

No abstract provided.

Safety And Driver Behavior Studies At Multiple Lane Approaches To Stop-Controlled Intersections, Karen Schurr, Daniel Sitorius

Nebraska Department of Transportation: Research Reports

Multiple-lane approaches (MLAs) controlled by stop signs are becoming increasingly common in Nebraska. Installation of MLAs occurs when a single approach lane can no longer adequately serve the minor road traffic volume, and a signal is unwarranted because Manual of Uniform Traffic Control Devices (MUTCD) warrants are not satisfied (7, FHWA, 2003). A common example of a location at which MLA stop-controlled intersections can occur in Nebraska is the rural intersection of two state or federal highways. Forty such intersections in Nebraska were available for study in this research. Additionally, such intersections are often located in suburban areas of Nebraska …

Centerline Curbing Treatment At Railroad Crossings For Improved Safety, Aemal Khattak, Dwight L. Mosby Jr., Gregory Mcknight, Brian Gardner

Nebraska Department of Transportation: Research Reports

The objectives of this research were to study unsafe actions of motor vehicle drivers at railroadhighway grade crossings, to evaluate centerline barriers in reducing those unsafe driver actions, and to note any maintenance or other issues with the barriers. Driver actions were observed at two railroad crossings before and after installation of centerline barriers. A comparison of observed driver actions in the pre- and post-barrier periods provided information on the effectiveness of the barriers in reducing unsafe driver actions while periodic inspection of the centerline barriers provided information on maintenance needs. A major concern of the Nebraska Department of Roads …

Intersection Safety, Aemal Khattak

Nebraska Department of Transportation: Research Reports

The objectives of this project included a study to determine the safety effects of intersection type (unsignalized, signalized, and interchange) on Nebraska expressway intersections, quantification of the safety effects of a Collision Countermeasure System (CCS), and update of the Nebraska Department of Roads (NDOR) expressway intersection guidelines. The CCS is an Intelligent Transportation Systems (ITS) traffic control device to warn drivers of conflicting cross-traffic at rural, non-signalized intersections. The goal was that if found effective, the CCS will become part of the intersection designer’s options for expressway intersection design (other options being an interchange, traffic signals, and traffic control signs). …

Safety Evaluation Of Left Turn Lane Line Width At Intersections With Opposing Left Turn Lanes, Aemal Khattak, Bhaven Naik, Vijay Kannan

Nebraska Department of Transportation: Research Reports

The objective of this research project was to evaluate the effectiveness of offset opposing left-turn lanes at signalized intersections in reducing the frequency and severity of left-turn related accidents. The Cities of Lincoln and Omaha offset opposing left-turns by widening leftturn lane lines in June 1999 at six intersections. The research team investigated traffic accident patterns between January 1994 and December 2002 at those six intersections by making comparisons with two control intersections (i.e. intersections at which left-turns were not offset by lane line widening) using a four-step research methodology. First, existing literature was reviewed to determine the extent and …

Safety Performance Evaluation Of The Nebraska Open Bridge Rail On An Inverted Tee Bridge Deck, Karla A. Polivka, John R. Rohde, Dean L. Sicking, Ronald K. Faller, James C. Holloway M.S.C.E., E.I.T.

Nebraska Department of Transportation: Research Reports

No abstract provided.