I believe 402 might be the east-west section of road just south of Loveland labeled "18". There is a "county Road 13C that crosses it but I've also seen a map that lists Weld County Road 13 as "Colorado Blvd".
Here is the google map of Weld County Road 13.
Weld County Rd 13 · Colorado
UPDATE: Found it - yes "18" is actually 402 and that runs straight west out of the park and ride she was last seen at. Good map here: Small picture clip of the 2 ponds attached.
Loveland Johnston Park and Ride The speed limit on 402 is 65 mph. If she was driving that on a donut, there's a solid chance it could have blown out as I had stated earlier (they are just not designed for those speeds). I hope it's not her, but I'm deeply worried that it is.