MIDWEST STATES POOLED FUND PROGRAM
Transition from Free-Standing Temporary Barrier to Reduced-Deflection Temporary Barrier
Sponsoring Agency Code
TPF-5(193) Supplement 78
The Wisconsin Department of Transportation sponsored a research project to develop a retrofit design for
reducing deflections for temporary concrete barriers (TCB) without anchoring barriers into the bridge deck
or roadway. This research was successful in reducing the deflection of the TCB system; however the
effort was focused on developing the length-of-need of the barriers and did not include design of a
transition between the reduced deflection TCB system and standard F-shape TCB segments. Thus, a
need exists to develop and evaluate a crashworthy transition between the new reduced deflection system
and free-standing TCB segments.
The current TCB design used by WisDOT and a number of other states is the F-shape TCB developed
through the Midwest States Regional Pooled Fund. This TCB system consisted of a 32-in. tall x 22.5-in.
wide x 12.5-ft long F-shape concrete barrier segment with a pin-and-loop type connection. The barrier
has been tested to TL-3 under both the National Cooperative Highway Research Program (NCHRP)
Report No. 350 and MASH safety criteria.
Often, temporary barriers are used in applications where it is desired that their deflection during vehicular
impacts be limited. During bridge construction, temporary barriers are often placed adjacent to the edge
of a bridge deck in order to provide adequate lane width. Free-standing temporary barriers used in these
types of installations pose a potential safety hazard to errant vehicles as there is a risk for the barrier
segments to be propelled off of the bridge. In addition, most work zones are restricted in terms of the
available lateral space in which to accommodate traffic and the construction activity, or temporary barriers
are used to separate opposing traffic. Thus, it is desirable to minimize the deflection of temporary barriers
in order to minimize the required buffer distance and maximize the space and number of lanes available
for traffic. Therefore, a need exists to develop systems to reduce the deflection of temporary barriers.
A significant amount of highway safety research has been focused on methods for constraining or limiting
the deflection of free-standing TCBs for applications where it is desired that their deflection during
vehicular impacts be limited. These designs have typically focused on tie-down applications that anchor
the TCB to the roadway surface or designs that stiffen or alter the connection between the barrier
segments. However, tie-down systems which anchor barriers to the roadway surface have several
drawbacks in that they are labor intensive, expensive, and increase worker exposure. They also pose the
risk of damaging the road surface during a severe impact event. Designs that alter or stiffen the
connection between the barrier segments have shown promise in limiting deflections, but their use
requires additional inventory and maintenance concerns for end users as it can require alteration of the
standard free-standing TCB design.
The Wisconsin Department of Transportation (WisDOT) desired a concept for reducing barrier deflections
without the need for additional tie-down anchors and that could be retrofitted to their current TCB with
minimal modification. MwRSF recently completed a research effort to develop and test a new, lowdeflection
system that utilized the F-shape TCB and did not require anchoring to the roadway surface.
The system consisted of a cap plate bolted across the TCB joint and continuous tubes running along the
sides of the barriers, as shown in Figure 5. Full-scale crash test no. RDTCB-2 was conducted on the final
iteration of the low-deflection TCB with the back of the TCBs offset 24 in. from the edge of a simulated
bridge deck. Test no. RDTCB-2 consisted of a 4,978-lb pickup truck impacting the low-deflection TCB
system at a speed of 64.8 mph and at an angle of 25.4 degrees. The impacting vehicle was safely and
smoothly redirected in the test and all of the barrier segments were safely retained on the edge of the
bridge deck. The peak dynamic lateral deflection of the barrier system was 40.7 in., which represented a
49 percent reduction in deflection as compared to the free-standing, F-shape TCB under MASH crash
The existing research focused on the design and evaluation of the length-of-need of the new, lowdeflection
TCB system. However, as with any barrier system, additional considerations must be taken into
account when implementing the barrier system outside the length-of-need, such as transitions to other
barrier systems. The design of transitions to other barrier systems, including free-standing F-shape TCB
segments, was outside the scope of this study and would require further research to design and evaluate.
Development of a transition between the reduced deflection TCB system and free-standing F-shape TCB
would need to consider several factors. First, the deflections of the two systems vary by approximately 50
percent. Thus, a transition in the stiffness of the system may be needed to prevent barrier pocketing and
provide safe and stable vehicle redirection. Second, the horizontal steel tubes of the reduced deflection
system would need to be tapered down to the surface of the free-standing TCB segments in a manner
that reduces the potential for vehicle snag and that does not induce vehicle climb or instability. This study
would develop and evaluate a transition to address the concerns.
The objective of this research effort is to develop a MASH TL-3 transition between the recently developed
non-anchored, reduced deflection TCB system and free-standing, F-shape TCB segments. The research
effort will focus on development of a design that safely transitions between the stiffness and deflection of
the two barrier systems while maintaining vehicle stability. The design will also focus on minimizing the
length of the transition and additional hardware components.
The research effort to design and evaluate a MASH TL-3 transition between the recently developed nonanchored,
reduced-deflection TCB system and free-standing, F-shape TCB segments will proceed in two
phases. Only Phase I is budgeted herein.
Phase I of the research effort will begin with a brief literature search to review previous transitions for TCB
systems as well as termination and transition elements used for box-beam guardrail and steel tube bridge
rail transitions. This information will provide insight on potential transition designs and methods for safely
tapering and terminating the horizontal steel tubes.
Following the literature search, transition design concepts will be brainstormed and developed. The
transition design concepts will be evaluated on potential safety performance, ease of installation, and
length. The most promising design concepts will be submitted to the Pooled Fund states for review and
comment, and design revisions will be made based on state feedback. Through this effort, the design
concepts will be ordered from most desirable to least desirable.
LS-DYNA simulations will be used to evaluate selected design concepts according to their safety
performance. Validated models of the reduced-deflection and free-standing TCB systems from previous
research will be used in the LS-DYNA analysis. The computer simulation analysis will begin with the
simplest, sponsor-favored design concepts, and complexity will be added as needed to improve safety
Once a transition design has been developed that demonstrates potential for meeting the MASH TL-3
impact criteria, a simulation analysis will be performed to determine a critical impact point for full-scale
At the completion of Phase I, a summary report of the research will be completed detailing the literature
search, computer simulation modeling, and recommendations for full-scale crash testing.
Phase II of the research effort will consist of evaluation of the transition between the recently developed
non-anchored, reduced-deflection TCB system and free-standing, F-shape TCB segments according to
MASH TL-3 through full-scale crash testing. MwRSF will prepare CAD drawings of the transition design
and fabricate and install the transition system at the MwRSF Outdoor Test Facility. It is anticipated that
one full-scale crash test, test designation no. 3-21 with a 2270P pickup truck vehicle, will be required to
evaluate the system. The critical impact point for the test will be based on the computer simulation effort
in Phase I. The full-scale vehicle crash test will be conducted, documented, and evaluated by MwRSF
personnel in accordance with the MASH guidelines.
After completion of the full-scale crash testing, a summary report of the research project will be completed
to include full-scale crash test results, evaluation of barrier performance, and recommendations for
implementation and barrier system installation. The transition design would also be submitted for approval
to FHWA if desired.
Development of a crashworthy transition system between the reduced-deflection TCB system and freestanding
TCBs would provide states with a robust TCB system capable of reducing deflections without
anchoring to the road surface. In addition, the system can be used in median applications and could be
attached to standard, free-standing TCB segments on each end to allow for easier implementation and
integration with existing work zones.
Snapshot of Recent Developments
130 Whittier Research Center
2200 Vine Street
Lincoln, Nebraska 68583-0853
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