1 00:00:00,715 --> 00:00:03,465 (logo whooshing) 2 00:00:10,180 --> 00:00:11,950 - [Narrator] Texas motorists are safer 3 00:00:11,950 --> 00:00:13,870 thanks to roadside barriers 4 00:00:13,870 --> 00:00:17,010 that keep vehicles from leaving the roadway. 5 00:00:17,010 --> 00:00:19,590 W-beam median guardrail barriers, 6 00:00:19,590 --> 00:00:24,110 and median concrete barriers both work well by themselves. 7 00:00:24,110 --> 00:00:26,000 But when the two systems are joined, 8 00:00:26,000 --> 00:00:30,250 it's that transition space that has not been mass approved, 9 00:00:30,250 --> 00:00:31,220 until now. 10 00:00:31,220 --> 00:00:34,966 - Any time we transition from one type of barrier to another 11 00:00:34,966 --> 00:00:37,480 that has big differences in deflection, 12 00:00:37,480 --> 00:00:40,640 it's important to have a gradual transition 13 00:00:40,640 --> 00:00:42,373 to keep the public safe. 14 00:00:43,550 --> 00:00:46,780 And this project specifically addresses the transition 15 00:00:46,780 --> 00:00:50,623 from double-sided guard rail to a rigid concrete rail. 16 00:00:51,610 --> 00:00:54,410 - We do have two mass crash tested devices, 17 00:00:55,664 --> 00:00:58,870 which is the double-sided, double-beam guard rail, 18 00:00:58,870 --> 00:01:01,260 and then we do have the concrete barrier. 19 00:01:01,260 --> 00:01:04,300 However, we don't have the connection tested between them, 20 00:01:04,300 --> 00:01:06,560 how you transition between one to the other. 21 00:01:06,560 --> 00:01:08,560 And that is not a simple task to do. 22 00:01:08,560 --> 00:01:11,070 We have to make sure the transition 23 00:01:11,070 --> 00:01:13,030 is really as safe as possible 24 00:01:13,030 --> 00:01:18,030 without any safety or performance issue. 25 00:01:18,079 --> 00:01:19,550 - [Chris] The double-sided guard rail 26 00:01:19,550 --> 00:01:23,290 is much cheaper to install than the concrete barriers. 27 00:01:23,290 --> 00:01:25,490 Districts might not have the funds to install concrete 28 00:01:25,490 --> 00:01:26,323 all the way down, 29 00:01:26,323 --> 00:01:28,743 but they might have enough funds to install 30 00:01:28,743 --> 00:01:30,343 double-sided guard rail. 31 00:01:31,730 --> 00:01:34,100 Also, double-sided guard rail allows 32 00:01:34,100 --> 00:01:36,070 for drainage underneath, 33 00:01:36,070 --> 00:01:38,980 which concrete barriers do not allow for enough drainage. 34 00:01:38,980 --> 00:01:41,770 This project allows us to make that choice 35 00:01:41,770 --> 00:01:44,310 and to make the best choice for the public. 36 00:01:44,310 --> 00:01:46,410 - [Akram] Then you want to have the stiffness 37 00:01:46,410 --> 00:01:47,610 to be kind of matching 38 00:01:47,610 --> 00:01:50,750 going from the medium W beam to the concrete. 39 00:01:50,750 --> 00:01:55,190 And that's where you start having a double W beam 40 00:01:55,190 --> 00:01:56,720 meaning is you're going to have four W beam 41 00:01:56,720 --> 00:01:59,100 nested in one side, nested in the other side. 42 00:01:59,100 --> 00:02:01,180 And then even for the tires, they come down, 43 00:02:01,180 --> 00:02:04,455 they're going to be engaging the face of the concrete. 44 00:02:04,455 --> 00:02:06,360 So you want to have a rub rail. 45 00:02:06,360 --> 00:02:08,030 So that's another W beam down there 46 00:02:08,030 --> 00:02:10,270 that just kinda makes sure the tires don't engage 47 00:02:10,270 --> 00:02:11,690 with the post as well. 48 00:02:11,690 --> 00:02:13,440 And the posts will be increased. 49 00:02:13,440 --> 00:02:15,213 So instead of have post at 6'3", 50 00:02:15,213 --> 00:02:20,213 they can be down to half of that, 3' 1/2" frequency. 51 00:02:20,930 --> 00:02:23,650 And you keep going with, that to even a quarter frequency. 52 00:02:23,650 --> 00:02:28,285 So with that, your stiffness is gonna be more like, 53 00:02:28,285 --> 00:02:29,688 this much and you're gonna go this much, 54 00:02:29,688 --> 00:02:32,090 this much until you go to very stiff concrete, 55 00:02:32,090 --> 00:02:34,623 and ensure you have a really smooth transition. 56 00:02:35,458 --> 00:02:37,270 - [Chris] A full scale crash test in this instance, 57 00:02:37,270 --> 00:02:40,470 showed us that this transition was going to be 58 00:02:40,470 --> 00:02:44,320 safe for the public, anywhere that it's impacted. 59 00:02:44,320 --> 00:02:45,950 - The test is basically you want to target 60 00:02:45,950 --> 00:02:48,170 the critical point. 61 00:02:48,170 --> 00:02:51,410 And because you have transitioning and have critical points, 62 00:02:51,410 --> 00:02:54,840 and these will be for the truck, as well for the small car. 63 00:02:54,840 --> 00:02:57,380 So there are two cars, two trucks, 64 00:02:57,380 --> 00:03:00,270 and three critical points there that we test at. 65 00:03:00,270 --> 00:03:02,290 And they're all under MASH. 66 00:03:02,290 --> 00:03:04,670 Now, all the tests were done 67 00:03:04,670 --> 00:03:07,590 at a hundred kilometers an hour, 60 miles per hour. 68 00:03:07,590 --> 00:03:09,950 At 25 degree impacting. 69 00:03:09,950 --> 00:03:13,190 - [Chris] From here, TxDOT will develop a standard, 70 00:03:13,190 --> 00:03:17,216 and we'll distribute the standard to our districts, 71 00:03:17,216 --> 00:03:20,310 and make the designers aware of it's availability. 72 00:03:20,310 --> 00:03:22,990 And that it is MASH compliant, 73 00:03:22,990 --> 00:03:25,438 and it has been tested in accordance with MASH. 74 00:03:25,438 --> 00:03:28,670 (truck crashing) 75 00:03:28,670 --> 00:03:29,760 - [Narrator] For more information, 76 00:03:29,760 --> 00:03:32,320 and to find the publications for this project, 77 00:03:32,320 --> 00:03:35,190 please visit the TxDOT research library 78 00:03:35,190 --> 00:03:36,683 at the link shown below.