Description of incident: Saturday, [XXX] I was in traffic on I [XXX] near the [XXX] exit in Indiana. It was a stop/go, stop/go event as 6 lanes were going down to 1 lane. I was behind a Kroger semi-truck. I had my foot on the brake. I thought the people next to me had started to move, but then I noticed that I was getting closer to the truck (while my foot was on the brake). I pushed the brakes down further. I felt normal resistance. Nothing happened. I hit the cancel button of the adaptive cruise multiple times on my steering wheel thinking that perhaps my adaptive cruise started my movement. I kept rolling. Kept hitting the brakes wondering why I didn't stop. No beeps went off like they normally do. I rolled into the truck. My adaptive cruise had been set to 70, and I had used it before the incident. It was still on standby, but not green. My odometer was around 9547. This happened around 9:50am. No beeping sounds started or emergency braking happened. I would approximate my speed of hitting around 3-5 mph. I hit the truck. I had tried to switch to neutral and then to park. I could not move the gear shaft. I was hitting the brake hold. Anything to make me stop. Nothing worked, and I hit the truck. I did not move after hitting the truck, maybe one of the things I attempted to do worked. My foot was still on the brake. I pulled over, turned off the car, and restarted it. I have not applied the adaptive cruise since then. I don't know if it had anything to do with the inci