why the output is not logically right?

i'm trying to implement this code. here are the problems:
1. i want to use variable typ_transport in further coding not just inside if.(it does not recognize the variable.)
2. the logic seems to be right but when i change the values in jsonStr (e.g. "walk" : true to "walk" : fasle ) the output does not print the right output.

Could any one help me with this? thanks

import json

jsonStr = '{"walk" : true, "bike" : false, "tram" : false}'
inputvar = json.loads(jsonStr)



if inputvar['walk'] == 'True' and inputvar['bike'] == 'False' :
    typ_transport='foot'

elif inputvar['walk'] == 'False' and inputvar['bike'] == 'True'  :
    typ_transport='bicycle'

class transport:


    if typ_transport=='foot':
        velocity=80
        typ='foot'
    elif typ_transport=='bicycle':
        velocity=330
        typ='bicycle'

    def __init__(self,typ,velocity):

        self.velocity = velocity
        self.typ = typ    

if  inputvar['tram'] == 'False' :

    radius= T*transport.velocity
    print (radius) 
else :
    print (typ_transport, 333)