Metro is making much of the fact that its new Farecard computerized collecting system has eliminated exact-change hassles for rail riders.

That's nice, but bus riders have no such luck, and those using both the bus and the train will still have to juggle change or books of tickets they buy from Metro sales outlets, plus Farecards.

A commuter living in the Landmark area of Alexandria (in Virginia Zone 1) and traveling to the area of 13th and G Streets NW during rush hour every day will go through this:

1. Board bus for Pentagon. Cost, 70 cents, exact change.

2. At Pentagon, transfer to train and ride to Metro Center. Computer takes 40 cents from Farecard. (Remember, there is no transfer from bus to train.)

3. In the evening, board train at Metro Center and get bus transfer. At Pentagon, computer takes 40 cents from Farecard.

4. Board bus for Landmark. Transfer is worth 50 cents, but rider must come up with 20 cents in zone charges, exact change.

The total cost of that trip, $1.70, is actually 10 cents cheaper than the total cost of a bus-only roundtrip to downtown Washington today. But today, the rider needs 90 cents in exact change twice.

When he begins to transfer to the train, he will need 70 cents, a Farecard (which he has to buy with real money at some point) and 20 cents.

Maryland commuters have the same problem until the last step - returning from the train to the bus. In that case, they will not have to pay bus zone charges, because Maryland officials have decided that a rail-to-bus transfer will get the rider a free bus ride no matter how many zones he crosses.