Bull dozer gone wild. For revenge!

In 2004, after a series of disputes with local officials and residents, Marvin Heemeyer takes to the streets of Granby, Colorado, in a modified bulldozer he secretly armored with layers of steel and concrete.

He had also equipped this “killdozer” with cameras and gun ports (more details on his gear are below).

Over a period of several hours, he proceeds to destroy multiple buildings in the town, including the town hall, a former mayor’s house, and other properties.

Which side do you believe in this epic small town battle over ego and fairness?

You can’t help but root for Marvin and the “killdozer”, right?



Where to Watch?

Stream the Tread documentary on Kanopy (w/ library card or student ID) at http://​; or on YouTube with ads at You can also rent it on AppleTV or watch it with ads on Roku, Tubi, Vudo and PlutoTV (check out for details).


  • Genre: Revenge
  • Release Date: 2020
  • Director: Paul Solet
  • Duration: 89 minutes

My Favorite Parts (Includes Spoiler Alerts!)

Here are some highlights or things that I took note of (or had questions about):

  • The bulldozer was a customized Komatsu D355A, dubbed the “MK Tank” (or “Marv’s Komatsu Tank”) by Heemeyer in his recordings.
  • The dozer had homemade armor plating, shielding the cabin, engine, and some track areas.
  • This armor, in some parts, was more than 1 foot thick. It was crafted using 5,000 psi Quikrete concrete mix placed between ½-inch tool steel sheets, sourced from a Denver automotive dealer, resulting in a makeshift composite armor.
  • The bulldozer was immune to small arms fire and highly explosive-resistant. It endured three external blasts and over 200 bullets without damage.
  • For vision, multiple video cameras were installed, transmitting to two dashboard monitors. These cameras were safeguarded with 3-inch clear bulletproof lexan shields.
  • Compressed-air nozzles were added to clear the cameras of dust.
  • To maintain a comfortable temperature, fans and an air conditioner were set up inside for Heemeyer.
  • He also incorporated three gun ports for a .50 caliber rifle, a .308 caliber semi-automatic rifle, and a .22 caliber rifle. Each was shielded with a ½-inch steel plate.
  • Cool scene: a police officer climbs onto the top of the killdozer.
  • Marv directs the dozer towards the propane company, emphasizing that these aren’t just small camper propane tanks.
  • The town attempts to use a “Scraper” to halt Marv’s rampage.
  • The killdozer’s tread becomes trapped in a store’s basement.

Update: Killdozer’s Part Found!

Apparently, the FBI forgot to get rid of one piece of the Killdozer when they disassembled it.

Somehow I think Marvin (rest his soul) would be happy about this.

Thanks for reading!

-Rob Kelly