1)check the boxes : "workers leave the old improvements " and "workers leave the forest" ,
2)use the workers not automatel till :
a) you have made all your cities connected (automated workers will not do this for you),
b) you have made all improvements that you think is useful ,
3)then make your workers automated for "making trade routes",check them after : a) when you find "replacement part " , they will not make lumbermill automatically,
b) when you find railroad ,because they will not make railroads automatically,
best,
2)use the workers not automatel till :
a) you have made all your cities connected (automated workers will not do this for you),
b) you have made all improvements that you think is useful ,
3)then make your workers automated for "making trade routes",check them after : a) when you find "replacement part " , they will not make lumbermill automatically,
b) when you find railroad ,because they will not make railroads automatically,
best,