One thing to remember is that the engineers overseeing the projects are not arborists. Also the tree maintenance workers and tree supervisors for Caltrans are not arborists.
Usually the way it works is the construction company is contracted to put the item ( whatever that may be) in a certain location, and if there is a tree or trees there, an arborist may be called in.
The engineers aren't familiar with trees, so it will be your call.
Caltrans also is about liability, meaning it may be better for you or the company you work for to make the call to remove the tree(s) so they aren't liable if/when the tree fails or a motorist crashes into it or crashes because of it.
I would be concerned mostly about what the specifics of the project are, who will be paying you, how much you will be compensated and when.
Another thing you may want to factor in is that on these projects there's a lot of contractors, subcontractors, and specialists. Planning isn't always well coordinated. If a closure is needed, will you be working in the contractors closure and they will be responsible, or will you have to contract/ be responsible for the closure?
Also, if the contractor has to name a " contractor supplied arborist" to get the job and you meet all the specs and do all the preliminary footwork, then it's determined you won't be needed, will you still be compensated for your time?
A lot to consider, but I think your next step should be to get as many details as possible from the people that contacted you to make a more informed decision.
