Sheikh et al. 1 PINNED-DOWN TEMPORARY CONCRETE BARRIER WITH TRANSITION SYSTEMS FOR LIMITED-SPACE WORK ZONE APPLICATIONS

Transcription

1 Sheikh et al. 1 PINNED-DOWN TEMPORARY CONCRETE BARRIER WITH TRANSITION SYSTEMS FOR LIMITED-SPACE WORK ZONE APPLICATIONS Nauman M. Sheikh Texas A&M Transportation Institute Texas A&M University System MS-3135 College Station, TX Phone: (979) Fax: (979) nauman@tamu.edu Roger P. Bligh Texas Transportation Institute Texas A&M University System MS-3135 College Station, TX Phone: (979) Fax: (979) rbligh@tamu.edu Paul Fossier Louisiana Department of Transportation and Development Louisiana Transportation Center 1201 Capitol Road, P.O. Box 9424, Baton Rouge, LA Phone (225) Paul.Fossier@la.gov Submission date: August 1, 2013 Post-review submission date: November 15, 2013 Word count: 7276 (5526 words + 7 figures)

2 Sheikh et al. 2 ABSTRACT In work zones where space for placing temporary concrete barrier is very limited (such as bridge expansion or repair), the barrier must be restrained to prevent large lateral deflection due to vehicle impact. This paper presents the development and testing of a restrained F-shape temporary concrete barrier that has very limited deflections. Additionally, two transitions were developed for use with the restrained barrier a transition from freestanding F-shape to the restrained barrier, and a transition from the restrained barrier to a rigid concrete barrier. Details of the development and crash testing of these transitions are also presented in this paper. The restrained temporary concrete barrier and its transitions were developed using a simple pinneddown anchoring method. Steel pins are simply dropped into inclined holes that start from the toe of the barrier and continue short distance into the underlying bridge deck or concrete pavement, thus locking the barrier in place. The drop-pin method makes it very easy to install the barrier, inspect for proper installation, and remove or relocate the temporary barrier in a work zone. The pinning method also results in minimal damage to the underlying bridge deck or concrete pavement. This makes it more desirable to use as opposed to some anchoring systems requiring through-deck bolting, which results in greater concrete damage and is difficult to install and relocate.

3 Sheikh et al. 3 INTRODUCTION Temporary concrete barriers (TCB) are commonly used in construction work zones to shield the motoring public from extreme drop-offs or to prevent it from entering the work zone. TCBs also prevent construction machinery or personnel from extreme drop-offs or entering adjacent traffic lanes. In some situations, temporary concrete barriers are used to separate twoway traffic. Certain amount of clear space must be provided behind the TCB to allow lateral barrier deflection in the event of a vehicle impact. In restrictive work zones with very limited space, such as during bridge construction or expansion with active adjacent lanes, or work zones with extreme drop-offs, TCBs must be restrained to limit lateral deflection. Commonly used restraining techniques include anchoring, bolting, or pinning to the bridge deck or pavement. While these methods limit barrier deflection, they require special installation procedures, which result in increased cost and installation time. Furthermore, vehicular impact with the restrained barrier usually results in damage to the deck or pavement, the extent of which varies depending on the method used. This is especially of concern with installations on thinner bridge decks. The removal or relocation of restrained TCBs is also more involved compared to freestanding barriers. There are few restrained TCB designs that have been crash tested to provide limited deflection requirements. (1)(2)(3)(4) Some of these designs require through the deck bolting, anchor bolts, or other constraining straps. Through the deck bolting is difficult to achieve in the field and can result in significant damage to thin bridge decks. Similarly, the use of anchor bolts requires adhesive bonding, which complicates barrier installation, inspection, and removal procedures. Furthermore, anchor bolts requiring longer anchoring depths are not suitable for use on thin bridge decks due to the considerations of causing deck damage. The authors have developed a restrained TCB design that limits barrier deflection using steel pins that are simply dropped into inclined holes that start from the toe of the barrier and continue short distance into the underlying bridge deck or concrete pavement, thus locking the barrier in place. The authors have also completed design and testing of transition systems that can be attached to the pinned-down TCB to allow transition from a freestanding barrier, and to a rigid concrete barrier. Details of the development and crash testing of the pinned-down concrete barrier, the transition from the freestanding barrier to pinned-down barrier, and a transition from the pinned-down to rigid concrete barrier are presented in this paper. The pinned-down method makes it very easy to install the barrier, inspect for proper installation, and remove or relocate the temporary barrier in a work zone. This method also results in minimal damage to the underlying bridge deck or concrete pavement, making it more desirable for use on thin decks compared with systems requiring through-deck bolting or adhesive anchors. PINNED-DOWN ANCHORED BARRIER SYSTEM Design Concept The commonly used F-shape barrier profile was used for the restrained TCB. Adjacent barrier segments were connected using a pin-and-loop type connection. As previously mentioned, the restrained TCB and its transitions were developed using a simple pinned-down anchoring method. Inclined holes are cast into the toe of the concrete barrier segments. The holes start from the traffic face of the barrier and exit near the bottom centerline of the barrier. The

4 Sheikh et al. 4 researchers determined that inclining the holes 40 degrees from the ground provided suitable anchorage for the barrier segments. (5) Once the barrier is placed on site, a drill machine is used to continue the inclined holes a certain distance into the underlying concrete bridge deck or pavement. Thus the steel pins (referred to as the drop-pins in this paper) are dropped into the inclined hole, passing though the barrier and into the bridge deck or pavement. This locks the barrier in place. Crash Testing At the time of the development of the pinned-down barrier, Manual for Assessing Safety Hardware (MASH) was under development. The pinned-down barrier was thus crash tested according to the National Cooperative Highway Research Program (NCHRP) Report 350 criteria. (6) The design was developed and crash tested for test level 3, which requires testing with a 1,806-lb small passenger car and a 4,409-lb pickup truck. Previous testing with the 1,806 lb smaller passenger car impacting the rigid F-shaped barrier at 62.2 mph and 20 angle has shown acceptable performance.(7) Under an impact from the small car, the pinned-barrier is expected to behave almost rigidly, thus rendering this test unnecessary. A crash test was therefore only performed for Test Designation 3-11 (i.e. 4,409-lb pickup impacting at 62.2 mph and 25 ). Presented next are the details of the barrier installation and the results of the full-scale crash test Design and Construction The precast TCB segments used in this crash test were 12.5 ft long and had the standard F profile. The barriers were 32 inches tall, 24 inches wide at the base, and 9.5 inches wide at the top. Horizontal barrier reinforcement consisted of eight #4 bars and the vertical reinforcement consisted of pairs of #4 bars spaced 18 inches on centers. These vertical bars were bent in a hook fashion. Adjacent barrier segments were connected using a pin-and-loop type connection. The loops were made of 3/4-inch diameter round stock steel. The outer diameter of the loops was 3.5 inches and they extended 2 inches outside the end of the barrier segment. The barrier connection was comprised of two sets of three loops. When installed, the distance between adjacent barrier segments was 1 inch. A 1-inch diameter and 30-inch long ASTM A449 connecting pin was inserted between the loops to establish the connection. A 2-inch diameter and ¼-inch thick washer was welded ¾ inches from the top of the connecting pin. The pin was held in place by resting the washer on insets built into the faces of adjacent barriers. Two inch diameter holes inclined 40 from the ground, were cast into the toe of each barrier segment. The holes started from the traffic face of the barrier and exited near its bottom centerline. The holes in the barrier were used as a guide to drill 1.75 inch diameter holes into the unreinforced concrete pavement. The depth of the holes inside the pavement was 6.25 inches when measured vertically. The average thickness of concrete pavement was 8 inches. The holes for the drop-pins were located 16-inches horizontally away from the ends of the barrier segments. A 1.5-inch diameter and inch long ASTM A36 steel drop-pin was placed into each hole. A ½-inch thick, 4-inch 4-inch A36 plate cover was welded to the top of each drop-pin. The plate covers were welded at a 5-degree angle from the vertical so that they matched the profile of the barrier toe. Inside the barrier segments, a 22-inch long U-shaped #4 bar was diagonally placed at the location of each drop-pin hole.

5 Sheikh et al. 5 The completed test installation consisted of eight barrier segments connected together for a total length of approximately 100 ft. Details of the barrier and the pin-down restraint are shown in figure 1a and the photographs of the test installation are shown in figure 1b and 1c. (a) (b) Figure 1 Pinned-down F-shaped temporary barrier before testing. A 2000 Chevrolet C2500 pickup truck with test inertia and gross static weight of 4674 lb, traveling at a speed of 62.7 mi/h, impacted the installation 4.0 ft upstream of joint 3-4 at an impact angle of The pickup was successfully contained and redirected in an upright manner. The vehicle lost contact with the barrier at seconds. Exit speed and angle could not be obtained due to excessive dust. The occupant risk numbers were below desirable range and maximum roll angle was 41. Maximum exterior crush to the vehicle was 21.7 inches and the maximum occupant compartment deformation was 1.1 inches in the left side firewall area near the toe pan with some separation in the seam. Damage to the barrier is shown in figure 2. Some spalling was observed in the vicinity of the impact, but the damage to the barriers was moderate. Maximum permanent and dynamic (c)

6 Sheikh et al. 6 deflections of the barrier were 5.76 inches and inches, respectively. The drop-pins adjacent to the impact joint were deformed (see figure 2d), but none of the pins pulled out of the concrete pavement. There was no significant damage caused to the concrete pavement. The holes in the concrete pavement in the vicinity of the impact are shown in figure 2b. All of the drop-pins in the barrier could be removed by hand, except the two adjacent to the joint of impact. These pins were removed after cutting them using a cutting torch. The pinned-down F-shape TCB passed the NCHRP Report 350 test level 3 requirements. Further description and details on crash test results can be found in Sheikh et al. (5) Once the development of the pinned-down F-shape TCB was completed, there was a need to connect the pinned barrier to freestanding TCB and/or rigid concrete barrier in many field applications. For this purpose, the authors developed two transition systems as described next. (a) (b) (d) (c) Figure 1 Pinned-down F-shaped temporary barrier after testing.

7 Sheikh et al. 7 TRANSITION FROM FREESTANDING TO PINNED-DOWN BARRIER In certain applications, a pinned-down barrier needs to connect to a free-standing barrier once the space needed for barrier placement is no longer as restrictive. Since the pinned-down barrier has a higher lateral stiffness compared to a freestanding barrier, a transition is needed for smooth redirection of the impacting vehicle. The researchers developed a transition design that can be used to transition from a freestanding F-shape temporary concrete barrier system to the pinned down F-shape barrier placed on concrete pavement or bridge deck. This transition was developed in accordance with MASH test level 3 criteria, using the F-shape pinned-down TCB design developed earlier. (5) Transition Concept The transition concept was kept simple with one standard F-shape barrier segment in the transition region that connected the freestanding and the pinned-down barrier segment (see top of figure 3). The design of the transition segment was kept exactly the same as the fully pinned segments. However, only one pin was used in the transition segment to pin it to the underlying concrete, near the anchored barrier end of the installation. The drop-pin used in the transition segment was the same 1½-inch diameter pin used in the fully pinned barrier segments. Determination of CIP In accordance with MASH s recommendations, the researchers used full-scale finite element (FE) vehicular impact analysis to determine the critical impact point (CIP) for the transition design. A full-scale FE model of the barrier system was developed to perform the impact simulations. Details of the FE modeling and analyses can be found elsewhere. (9) However, results of the analyses are described in this paper. Vehicle impact simulations were performed at the four impact locations shown in figure 3 to determine the critical impact point for use in crash testing. First impact point was selected just upstream of the anchoring pin in the transition segment. Second, third and fourth impact points were spaced 6.25 ft apart. Each of the simulations was performed using test 3-21 impact conditions of MASH (i.e., 5000-lb pickup truck impacting the installation at 62.2 mi/h and 25 degrees, respectively). The objective of these simulations was to determine the CIP, at which the vehicle would have the greatest instability due to pocketing of the barrier system. Results of the impact analyses are also shown in figure 3. In addition to the four simulation cases described above, a simulation was performed with the vehicle impacting just the pinned-down anchored concrete barrier system. Results of this simulation were used to compare the performance of the transition impact simulations. Simulation results for impacts closer to the pinned-down barrier (impact point 1 and 2) indicated that the barrier segments do not deflect significantly (see simulation results for impact points 1 and 2 in figure 3). The behavior of the barrier for impact points 1 and 2 was very similar to impact with just the pinned-down barrier installation (also shown in figure 3). Vehicle impacts closer to the standard anchored barrier do not allow enough interaction with the vehicle for the barrier segments in the free standing and the transition region to deflect laterally. Thus, vehicle pocketing cannot be evaluated with these impact points. For this reason, it was concluded that impact points 1 and 2 are not the critical impact points.

8 Sheikh et al. 8 Impact point 4 Impact point 3 Impact point 2 Impact point 1 Free-standing Barriers Free-standing Segment Transition Segment Anchored Segment Anchored Barriers Impact with just the pinneddown barrier (no transition) Impact Point 1 Impact Point 2 Impact Point 3 Impact Point 4 Figure 3. Transition design concept and simulation results of impacts at various impact points (top view showing initial state and maximum barrier deflection).

9 Sheikh et al. 9 Simulation results for impact points 3 and 4, which are farther upstream from the start of the standard anchored barrier segments, showed greater lateral barrier deflection than impact points 1 and 2. For impact point 3, the vehicle had significant chance of pocketing due to the lateral deflection of the barriers. Even though the lateral deflection increased for impact point 4, the performance at this point resembled that of a free standing barrier, as opposed to a transition. Simulation results also showed that the vehicle was more stable for impact point 4 compared to impact point 3. Since impact point 3 offers greatest chance of vehicle instability and pocketing, it was selected as the CIP for the transition design. This impact point was ft upstream from the joint between the transition barrier segment and the fully pinned barrier segment. A crash test was subsequently performed at this impact point, and the details are presented next. Crash Testing Test 3-21 of MASH (5000-lb pickup, 62 mi/h, 25 degrees) was performed to evaluate the performance of the transition design. The test with the lighter 2425-lb passenger car (test 3-20 of MASH) was not performed as the lighter vehicle is not expected to result in greater lateral barrier deflection and vehicle pocketing during the impact, or result in higher impact force on the transition segments compared with the heavier 5000-lb pickup. Thus, the test was conducted with the 5000-lb pickup only The overall length of the test installation was 201 ft-3 inches. The installation was comprised of ft-6 inches long precast concrete barrier segments that were 32 inches tall and had the standard F profile. The first eight segments (1 to 8) were freestanding and were not anchored to the underlying concrete pavement. Barrier segment 9 was pinned to the underlying concrete pavement using a single 1-1/2 inch diameter steel pin near the downstream end of the segment. Segments 12 through 16 were pinned using two 1-1/2-inch diameter steel pins per barrier segment. The barriers were placed on an unreinforced concrete pavement that was nominally 6 to 8 inches thick. The detailed design of the precast F-shape barrier segments, the connection between adjacent segments, and the drop pins used to anchor the pinned-down barrier segments were the same as described for the test with the pinned-down TCB system. The change in the barrier design was that the inch diameter inclined holes used to pass the drop pins were changed to 1-7/8-inch wide and 4-inch long slotted holes. The inclined holes/slots are used as guides to drill a hole in the underlying concrete deck or pavement for receiving the drop pin. The slotted holes provide some longitudinal tolerance for installation on reinforced concrete decks where it can help in missing a rebar while drilling the hole. Details and photographs of the test installation are shown in figure 4. The target CIP was ft upstream of the joint 9-10 of the barrier installation. A 2007 Dodge Ram 1500 was used in the test, which weighed 4999 lb. The actual impact speed and angle were 61.1 mi/h and 25.4 degrees, respectively. The actual impact point was 15.0 ft upstream of the joint between the 9 th and 10 th barrier segment. At approximately s after the impact, segments 8 and 9 began to deflect towards the field side, and at s, the vehicle began to redirect. The vehicle began to travel parallel with the barrier at s, and the rear of the vehicle contacted the barrier at s. At s, the vehicle lost contact with the barrier traveling at an exit speed and angle of 49.8 mi/h and 14.1 degrees, respectively. Brakes on the vehicle were applied at 2.4 s after impact, and the vehicle subsequently came to rest 157 ft downstream of impact and 7 ft towards traffic lanes.

10 Sheikh et al. 10 Figure 4 Transition from free-standing F-shape barrier to pinned F shape barrier prior to test. Moderate concrete damage occurred at the adjacent ends of segments 8 and 9, and significant damage occurred to the adjacent ends of barrier segments 9 and 10. The maximum dynamic and permanent deflections were 3.9 ft and 3.7 ft, respectively. Maximum occupant compartment deformation was 1.5 inches in the lateral area across the cab at hip height. The occupant impact velocity in the longitudinal direction was 13.4 ft/s and the ridedown acceleration was 5.7 Gs. In the lateral direction, the occupant impact velocity was 19.4 ft/s and the ridedown acceleration was 13.3 Gs. All occupant risk values were within the MASH thresholds. The vehicle redirected in a stable manner. Photos the test installation and the vehicle after the crash test are shown in figure 5. The freestanding to pinned-down TCB transition design was considered to have performed acceptably under the MASH testing criteria. More details about the test installation and the crash testing can be found in the test report. (9)

11 Sheikh et al. 11 (Installation After Test) (Joint 8-9) (Joint 9-10) Figure 5 Test installation and vehicle after test.

12 Sheikh et al. 12 TRANSITION FROM PINNED-DOWN TO RIGID CONCRETE BARRIER The researchers also developed and crash tested a transition barrier design that can be used to transition from the pinned-down F-shape TCB placed on concrete to a permanent concrete barrier. The transition was developed to meet MASH test level 3 criteria. The researchers evaluated various rigid concrete barrier designs to select a design that was deemed most critical with respect to the potential for vehicle snagging and instability during redirection in the transition region. Details of these comparisons can be found elsewhere. (10) The researchers determined that a 42-inch tall rigid single slope concrete barrier presents the greatest potential for snagging if used in the transition design. A transition design that performs acceptably for the 42 tall rigid single slope barrier can also be adapted with slight modifications to most other rigid barrier designs. Thus the transition was developed for transitioning from the 32-inch tall pinned down F-shape barrier to the 42-inch tall rigid single slope barrier. Transition Concept The transition was comprised of the pinned-down F-shape TCB placed adjacent to the 42-inch tall single slope barrier. To accommodate the 10-inch difference in barrier height while transitioning from the 32-inch tall F-shape barrier to the 42-inch tall single slope barrier, a cap with a tapered profile was bolted to the top of the F-shape and the single slope barriers. On the traffic side, a nested thrie beam cover was bolted to the F-shape concrete barrier segment and the rigid single slope barrier using the standard thrie beam end shoes. This cover was intended to provide a smoother transitioning surface during the change in the barrier profiles from F-shape to single slope. It was also used to establish a connection between the rigid and the pinned-down barriers. One the field side, a steel plate was bolted to the F-shape and the single slope barriers. The transition concept developed is very similar to the design previously developed and crash tested by Midwest Roadside Safety Facility (MwRSF). (11) The MwRSF's transition was developed to transition from free standing F-shape barrier to a 42-inch tall rigid single slope barrier. The transition barrier segments in this design were pinned over asphalt, which makes the design problem very similar to this research. However, the MwRSF design was developed for a median application, whereas in this research, the transition was developed for roadside or bridge rail applications. Furthermore, the pinned barrier segment adjacent to the rigid barrier in MwRSF's case used six anchoring pins, whereas it uses two anchoring pins in this research. Crash Testing The overall length of the test installation was 104 ft-6 inches. The installation was comprised of seven 12 ft-6 inch long pinned-down TCB segments that had the standard F profile. The detailed design of the pinned-down segments, the connection between adjacent segments, and the drop pins used to anchor the pinned-down barrier segments were the same as in the test of free-standing to pinned-down transition. The downstream end of the pinned-down barrier installation was connected to a 16 ft long and 42 inches tall permanent single slope concrete barrier with an 11-degree slope of the barrier s traffic-side face. The connection loops on the downstream end of the pinned-down F-shape barrier segment placed adjacent to the permanent single slope barrier were cut off. This allowed placing the pinned-down F-shape barrier segment flush to the rigid single slope barrier. The connection between the F-shape barrier and the single slope barrier was established using nested 12-gauge thrie beam guardrails. At one end, the nested thrie beam guardrails were connected to the trafficside face of the F-shape barrier segment, and at the other end, the guardrails were connected to

13 Sheikh et al. 13 the traffic-side face of the single slope barrier. The connection to the barrier was made using a 10 gauge thrie beam end-shoe and five 7/8-inch diameter, ASTM A325 bolts that passed through the cross-section of the barrier and were fastened using heavy hex nuts on the field side of the barriers. On the field side of the barriers, a 1/4-inch thick and ft long ASTM A36 steel plate was fastened to barriers using the top two through-bolts used to connect the thrie beam endshoes. An 8-inch 8-inch 2-1/2-inch wood block spacer was attached to the 1/4-inch steel plate near the end of the pinned-down F-shape segment placed adjacent to the single slope barrier. The wood block spacer was attached to the steel plate using a 5/8-inch diameter carriage bolt that was bolted with a hex nut on the field side of the steel plate. The 1/4-inch steel plate and the wood spacer were used to reduce slack near the top of the F-shape and the single slope barrier profiles, thus providing additional resistance to the lateral roll of the pinned-down F- shape barrier during vehicle redirection. A transition cap made of 1/8 inch thick ASTM A36 steel was attached to the top of the F- shape and single slope barriers. The transition cap ramped 10 inches over a length of 48 inches to transition from the 32-inch tall F-shape barrier to the 42-inch tall single slope barrier. The transition cap was reinforced using five stiffener plates that were also 1/8 inch thick. At each end, the cap was bolted to the top of the F-shape and the single slope barriers using two 1/2-inch diameter Hilti HAS adhesive anchors. The adhesive anchors were installed using Hilti HIT500 epoxy and had a 4-1/2-inch embedment. The 42-inch tall permanent single slope barrier was 16 ft long, 24 inches wide at the base, and 8 inches wide at the top. The barrier had an 11-degree slope of the traffic and field sides. The barrier was reinforced using 16 #4 lateral stirrup bars that were bent to conform to the profile of the barrier and provide a 2-inch concrete cover. The lateral stirrups were spaced 12 inches apart along the length of the single slope barrier. The longitudinal reinforcement of the single slope barrier was comprised of ten #5 bars that were placed inside the lateral stirrup and spaced vertically along the height of the barrier. The barrier was cast over a reinforced concrete foundation that was 48 inches wide and 8 inches deep. At the location of each lateral stirrup in the single slope barrier, an L-shaped #6 bar was placed inside the concrete foundation with the longer leg raised upwards into the single slope barrier. The shorter leg of L-shaped bar was placed 2 inches above the bottom of the concrete foundation. At the location of each L-shaped bar, a 44-inch long #4 bar was placed laterally. The 44-inch bars were placed 2 inches above the bottom of the concrete foundation. The longitudinal reinforcement of the concrete foundation was comprised of four #4 bars that were 15 ft-9 inches long and were spaced 12 inches apart. The concrete foundation was connected to the surrounding unreinforced concrete apron using eight #5 bars that were 12 inches long. The #5 bars were installed in the surrounding concrete with a minimum 5-5/8-inch embedment using Hilti HIT 150 epoxy. These bars were placed at a height of 5 inches from the bottom of the concrete foundation. Details and photographs of the test installation are shown in figure 6.

14 Sheikh et al. 14 Figure 6 Test installation details and photos. MASH test 3-21 was performed with the test installation (i.e. a 5000 lb pickup impacting the transition at a speed of 62.2 mi/h and an angle of 25 degrees). The target impact point was 51.6 inches upstream of the joint between the pinned-down F-shape barrier and the permanent single slope barrier. This impact point was selected based on guidance provided in Table 2.6 of MASH. This is the recommended distance for testing upstream of the joint in a rigid barrier system that has the highest potential for vehicle snagging. Since the greatest variation in the stiffness of the barrier exists at the joint between the pinned-down F-shape and the permanent single slope barrier, along with the change in barrier profiles and heights, it is believed that the recommended 51.6 in. upstream of this joint is the appropriate critical impact point (CIP) for this design. A 5026-lb 2007 Dodge Ram 1500, travelling at 62.8 mi/h impacted the transition 50.7 inches upstream of joint between the pinned-down F-shape and the permanent single slope barrier at an impact angle of 25.7 degrees. The transition reached maximum deflection of 5.7 inches at s. At s, the vehicle lost contact at an exit speed and angle of 48.9 mi/h and 8.6 degrees. Brakes on the vehicle were applied at 0.95 s, and the vehicle subsequently came to rest 196 ft downstream of impact and 18 ft toward traffic lanes from the traffic face of the transition.

15 Sheikh et al. 15 The thrie beam guardrail element was deformed in the area of impact. Movement at the joint between the end of barrier 7 adjacent to the rigid concrete barrier moved 2.5 inches toward the field side. Maximum dynamic deflection during the test was 5.7 inches. The longitudinal OIV was 22.6 ft/s and the ridedown acceleration was 3.6 Gs. The lateral OIV was 28.2 ft/sand the ridedown acceleration was 10.4 Gs. The vehicle was successfully contained and redirected in smooth manner. The performance of the transition was deemed acceptable under MASH testing criteria. Figure 7 shows the test installation and the vehicle after the crash test. More details about the installation design and crash testing can be found in the test report. (10) Figure 7 Test installation and vehicle after crash test.

16 Sheikh et al. 16 CONCLUSIONS The pinned-down F-shaped TCB developed in this research is easy to install, inspect, and remove or relocate, and minimizes damage to the bridge deck or concrete pavements. The mechanism uses the pinned-down approach to restrain the barriers. For installation, precast inclined holes in the barrier are used as a guide to drill holes in the underlying concrete pavement or deck. The barrier is then restrained by simply dropping the pins into these holes. For removal or relocation of the barrier, the pins can be removed by hand to free the barrier. In case of a vehicular impact, the deflection of the impacted segments is likely to bend the drop-pins such that they cannot be lifted by hand. Such segments can be lifted using a fork lift and the pins can be removed using a cutting torch. This procedure however is needed for a very small number of drop-pins. The design of the transition developed to attach the pinned-down barrier to the freestanding barrier is relatively simple. Same barrier segment can be used for the transition when needed. This eliminates the need to have a special transition segment in the inventory. The transition design from the pinned-down to the rigid concrete barrier is also relatively simple. The pinned down barrier system can also be used to transition from freestanding TCB system to a rigid concrete barrier. In this case, four segments of the pinned down TCB can be used such that it is connected to the freestanding barrier system at one end, and the rigid concrete barrier at the other end using the transition designs developed in this research. ACKNOWLEDGEMENTS This research was performed under a pooled fund program between the State of Alaska Department of Transportation and Public Facilities, California Department of Transportation (Caltrans), Louisiana Department of Transportation and Development, Minnesota Department of Transportation, Pennsylvania Department of Transportation, Tennessee Department of Transportation, Texas Department of Transportation, Washington State Department of Transportation, West Virginia Department of Transportation, and the Federal Highway Administration. The authors acknowledge and appreciate their guidance and assistance.

17 Sheikh et al. 17 REFERENCES 1. W. L. Beason and D.L. Bullard, Jr., Development of a Limited-Slip Portable Concrete Barrier Connection. Research Report 1959, Texas Transportation Institute, College Station, TX, B.W. Bielenberg, R.K. Faller, D.L. Sicking, J.R. Rohde, J.D. Reid, and J.C. Holloway, Development of a Tie-Down Systems for Temporary Concrete Barriers, Midwest Roadside Safety Facility, Lincoln, Nebraska, K.A. Polivka, B.W. Bielenberg, R.K. Faller, D.L. Sicking, J.R. Rohde, J.D. Reid and J.C. Holloway, Development of a Steel H-Section Temporary Barrier for Use in Limited Deflection Applications. Midwest Roadside Safety Facility, Lincoln, Nebraska, K.A. Polivka, R.K. Faller, J.R. Rohde, J.C. Holloway, B.W. Bielenberg, and D.L. Sicking, Development and Evaluation of a Tie-Down Systems for Redesigned F-Shape Concrete Temporary Barrier, Midwest Roadside Safety Facility, Lincoln, Nebraska, N. M. Sheikh, R. P. Bligh, and W. L. Menges, Crash Testing and Evaluation of the 12 ft. Pinned F-shaped Temporary Barrier, Research Report , Texas Transportation Institute, College Station, TX, H.E. Ross, Jr., D.L. Sicking, R.A. Zimmer and J.D. Michie, Recommended Procedures for the Safety Performance Evaluation of Highway Features, National Cooperative Highway Research Program Report 350, Transportation Research Board, National Research Council, Washington, D.C., Buth, C. E., N. M. Sheikh, R. P. Bligh, W. L. Menges, and R. H. Haug, NCHRP Report 350 Testing of Montana Portable Concrete Safety Shape Barriers, Report FHWA/MT /8162. Texas Transportation Institute, College Station, April AASHTO (2009). Manual for Assessing Safety Hardware. Washington, DC, American Association of State Highway and Transportation Officials 9. Sheikh N. M and Menges W. L, Development and Testing of a Transition from Free-Standing to Pinned Temporary Concrete Barrier, Report Texas A&M Transportation Institute, College Station, March Sheikh N. M and Menges W. L, Transition Design for Pinned-Down Anchored Temporary Barrier to Rigid Concrete Barrier, Report Texas A&M Transportation Institute, College Station, November Bielenberg, R.W., Rosenbaugh, S.K., Faller, R.K., Reid, D.L., and Lechtenberg, K.A. Transition of Temporary Concrete Barrier, Journal of Transportation Safety & Security, Taylor & Francis, Volume 4, Issue 2, April 2012, pages