Casey has built two mobile armored trucks called Tornado Intercept Vehicles (TIV and TIV2) to film from inside the tornadoes he chases with Joshua Wurman and the Doppler on Wheels radar trucks (DOW 2-DOW 7).^[5][6] Construction began on the TIV in 2003 and cost over $80,000. Sean began concept of the TIV after he was locked out of a minivan while a tornado was dangerously close. The windows are bullet resistant polycarbonate at 1.5 inches thick. There's a 7.3 liter Ford Power Stroke turbodiesel under the hood, and the top speed is 65 mph. The TIV weighs in at 8 tons and holds 60 U.S. gallons of fuel.^[7] Construction began on TIV2 in September 2007 with help from Great Plains Technology Center in Lawton, Oklahoma^[8] after Sean realized he needed to upgrade his vehicle. TIV2 weighs in at 7 tons and is a 4 wheel drive 3 axle vehicle. It stands taller than the original TIV and is capable of going on mud and unpaved roads without the fear of getting stuck. The original TIV has 2 wheel drive and extremely low ground clearance that would cause it to get stuck on unpaved roads. It is powered by a 6.7-liter Cummins turbodiesel engine, modified with propane and water injection to produce 625 horsepower. This gives TIV 2 an estimated top speed of over 100 mph. Fuel capacity is 95 U.S. gallons, giving TIV 2 an approximate range of 750 miles. The body of TIV 2 is constructed of a 1/8-inch steel skin welded over a 2-inch (51 mm) square tubing steel frame. The windows in TIV 2 are all bullet resistant 1 5/8 inch interlayered polycarbonate sheets and tempered glass. TIV 2 also features an IMAX filming turret similar to the one on the original TIV. The original TIV's somewhat cumbersome hydraulic claws were not used on TIV 2 in favor of 4 hydraulic skirts that drop down to deflect wind over the TIV to stabilize it and protect the underside from debris plus 2 stakes that extend down 42 inches. The stakes were so effective that after the first use TIV 2 couldn't retract the stakes and they had to be dug out by hand.