This is a detailed planning question, which I hope is allowed. I'm not sure if we have anyone on the forum from the Tri-Cities who would know the answer. This is being planned for very late September/very early October in two years time at the earliest (so no issues with baking summer heat). It's frustratingly slipped another year very recently.
I have a fixed appointment/event elsewhere in the state on 27 September then a two day (at least) visit to Yakima on the way over to visit a grave among other things. Hence the date.
To get to the Manhattan Project Visitor Centre for the tours I am looking to get off the Ben Franklin bus at Fire Station 73 then walk up what seems to be a path (not a shoulder) alongside SR240 from the railroad crossing. However when the Google Car went up there, construction was ongoing and I can't tell if that path links up with the Urban Greenway at Jadwin for the small section to the railroad. That little bit looks very hostile on Street View. It also seems I can't walk up Snyder as that appears to have no railroad crossing.
This is the way I personally travel, so please don't tell me Uber. But I hope you can see I have used the travel tools I have to try to answer this myself.
This isn't my style to ask this kind of question.
I will also be honest and say that there is a small (just developing, and not really favoured) chance that this will become a road trip, in which case the question vanishes.