Create a Measure based on text in table

Hello 

I need help creating a measure based on data in a table. Please see example blow 

I have a table Named ModelMaster 

In the table I have fields MODELCODE      VEHTYPE

Table Name: ModelMaster

MODELCODE      VEHTYPE

ASD12                C

DSA12                T

AAA33                

I need to create a measure named VEH RC  Eligable based on the following logic

VEH RC Eligable = If VEHTYPE = "C" then "Tri" 

                               else  If VEHTYPE = "T" then "Bi" 

                                       else If VEHTYPE = "" then "UNK"

                                               end if   

                                       end if 

                                end if  

result 

MODELCODE      VEHTYPE  VEH RC Eligable 

ASD12                C                       TRI

DSA12                T                        BI

AAA33                                         UNK 

Please advise as to how best I might accomplish this using a measure. 

Thank You in advance for any assistance you can provide. 

PS Colors are only provide as highlight, colors are not needed as part of the visual ouput