Understand
Most of it happens before a court is involved
Owners usually picture a lawsuit. In practice the great majority of acquisitions are negotiated, and the stages before any filing are where the amount is actually decided.
The sequence
Seven stages
Planning
The agency decides what to build and where, through design and environmental review. This is the only stage at which the route is realistically open to influence, and it usually closes before owners are contacted.
Notice
A letter saying your property may be needed. It obliges you to do nothing.
Appraisal
The property is valued, usually by an appraiser the agency retains. This single document drives everything afterwards.
Offer
A formal written offer. In federally assisted acquisitions it must be not less than the approved appraisal figure.
Negotiation
Offer and counteroffer, often over months. Most acquisitions end here, above the opening figure.
Petition
If no agreement is reached, the agency files in court. This starts a strict deadline, and in quick take states possession can follow quickly.
Determination
A commission, judge or jury fixes compensation, with appraisers on both sides giving evidence. Most matters still settle before this.
Where owners have influence
Three moments that matter
At the inspection
Telling the appraiser what is not visible: drainage, wells, how the property is used, land you own and work as one unit.
Before accepting
Everything is open until a settlement is signed, and nothing is open afterwards.
In the counteroffer
Evidence moves an agency. Dissatisfaction does not, however strongly expressed.
Questions about the process
How long does the whole thing take
From first notice to payment, commonly several months to a couple of years. Planning before that often runs for years, and contested matters can run longer.
Can I stop it
Realistically not at the individual property stage. The route is settled during planning, and challenges to the right to take rarely succeed.
Will I have to go to court
Probably not. Most acquisitions settle, and many that are filed settle afterwards.
Can they take possession before paying me
In quick take states, yes, by depositing their estimate with the court. You can usually draw it down while continuing to argue for more, but check that in your state first.
Find the site that answers your question properly
This is a starting point. The detailed answers live on the sites built for each question, and on the site for your state.