Datagrid checkbox binding issue

Question

I have bound the datagrid checkbox column with the property of the dataobject. The value of the property for example is Land,Sea ,Air etc. I need to set the checkbox to checked if it is land. How do I do it. My current code is as follows

<DataGrid.Columns>

<DataGridTextColumn Header="Type" Binding="{Binding Path=Vehicle}" />

<DataGridTextColumn Header="Make" Binding="{Binding Path=Vehicle.Make}" />

<DataGridTextColumn Header="Model" Binding="{Binding Path=Vehicle.Model}" />

<DataGridTextColumn Header="No of Wheels" Binding="{Binding Path=Vehicle.NumberOfWheels}"/>

<DataGridTemplateColumn Header="Road Vechile">

<DataGridTemplateColumn.CellTemplate>

<DataTemplate>

<CheckBox IsChecked="{Binding Path=Vehicle.Environment,Mode=OneWay }"/>

</DataTemplate>

</DataGridTemplateColumn.CellTemplate>

</DataGridTemplateColumn>

</DataGrid.Columns>