The Virginia Department of Transportation (VDOT) upgraded an existing Road Systems Inc. (RSI) NCHRP 350-compliant SKT terminal with RSI’s new MSKT, which is MASH Test Level 3-compliant. This installation was on a busy stretch of road at a left exit off of I-64 leading to I-95 just north of Richmond.
Like the SKT, the MSKT uses the same sequential kinking technology that allows the W-Beam rail section to exit the impact head and bring an errant vehicle impacting it head-on to a controlled stop.
While the MSKT incorporates enhancements to the impact head and anchorage system, it shares many of the same specifications with its SKT predecessor—including a similar footprint, the same W-Beam rail sections, same anchor bracket/cable and many of the same posts.
In the case of this installation, a transition was needed between the MSKT, which features a 31-in. rail height and guardrail splices that occur mid-span between posts, and the existing standard at 27 ¾-in. rail height, in which splices occur at the posts.
The first 50 ft of the MSKT terminal has the first rail splice at Post 3. Then a special length panel puts the next splice between Posts 4 and 5. Standard 12 ft-6 in. rail sections continue, creating splices between Posts 6 and 7, and 8 and 9. At that point, there was a reduced post spacing of 3 ft-1½ in. between posts 9 and 10, which allowed for a splice at Post 11.
Also at Post 9, a 25-ft transition began between the MSKT rail height of 31 in. down to the height of the in-place guardrail at a height of 27 ¾ in. VDOT regulations specify that “transitions from 31-in. GR-MGS1 to 27 ¾-in. GR-2 shall be accomplished with two standard 12 ½-ft sections of W-Beam,” and this was done to spec between Posts 9 and 14.
It did not take long for this new MSKT unit to be put to the test. Just two days after it was installed, a driver in the northbound (left) exit lane decided at the last minute to switch to the (right) southbound route and hit the MSKT with the left front corner of their car. The vehicle was safely controlled, and the MSKT head ended up just inside the yellow line on the road after kinking a few feet of rail. Emergency crews were dispatched to cut the W-Beam just before Post 3 and pull it out of harm’s way. Repairs to the terminal have now been completed.
