The subject property is currently a residentially zoned parcel. A reginoal road widening will be occurring on the Eastern boundary of the lot. Currently there is a full access exit/entry. Upon road widening, there will be a planned median on the regional road, effectively resulting in limited access (i.e. right in and right out). Can the Region simply expropriate in this case or can the property owners make a claim for injury in respect of access denial and if so, what is the basis of any valuation to be used in conjunction with this claim? Not sure if I've laid out all the necessary facts.
The situation you describe is quite common. Highway widening projects often include median barriers designed to eliminate left-turns thereby improving traffic flow. Of course, if you own a property adjacent to the improved highway, you may not be too happy about losing your previous left-turn access rights.
Whether you are entitled to compensation will depend upon the applicable legislation. In many cases your right to compensation will also depend upon whether land has been expropriated from you to construct the improved highway.