The shortcut path to the Park and Ride is pretty well maintained. She wouldn't have been walking on or through underbrush, but rather on packed dirt or gravel. Around the culvert, she would have been wading through vegetation- perhaps even blackberry bushes, which run rampant here at times. It would have been messy and wet.
I hate what I am about to say, but. For a lot of reasons, I don't think this was suicide. But if she had wanted to do that, why in the world would she have parked her car in its usual spot, set up an alibi of sorts, but one that would IMMEDIATELY alert her carpool that something was wrong, when she stopped texting? Her house is quite close to a very large, densely wooded park. If she HAD wanted to walk somewhere permanent, it was right there at hand. Why drive away, catch a local bus to retrace part of her drive, be dropped off at a relatively busy intersection 8 blocks away from the culvert, and walk along a well traveled road to get to the culvert. And climb through brush and whatnot in full view of commuters? (It would have been daylight by the time she arrived.) Into a nasty wet culvert on a cold damp morning. IMO it is just not feasible at all.
I know suicides can seem to act irrationally in the lead-up to their actions. But this just seems so very convoluted. IMO and all that jazz but it just doesn't work for me at all.
Let us also remember that it was reported somewhere - I have no link- that the local transit operators checked their bus cameras. No one spotted her on a bus.