trains are better than buses

I've seen and heard the argument that Minneapolis and other US cities shouldn't expand light rail networks because building devoted bus lanes is just as good and would save a lot of money. Having lived in a city with effective rail transit and having ridden the bus a fair amount, I can now say this is false. There are differences between trains and buses that go beyond getting stuck in traffic.

Getting on and off
This is a two-fold benefit of trains. Since train tracks are recessed below the platforms, there are no steps to climb when boarding a light rail or subway train. Furthermore, a train has many doors that run the length of the platform. This eliminates the queuing problem busses face because they have just one or two entrances.

Riding itself
Trains are much smoother, much quieter and just generally a lot more pleasant to ride than busses. Try reading a book on a city bus. It's not easy.

Trains run established lines
The infrastructure of a train system is such that you can't just up and move a station or line. This makes the trains system much more intuitive and easy to use. It also explains why train lines are responsible for economic development around stations, since businesses can count on easy accessability and a stream of passersby through public transit.

Carrying capacity
A train line will always be able to transport more people than a bus line, because you can put more people in a 300 foot long train than a 50 foot long bus. It only makes sense.

Ridership
There are a lot of people who will ride the train but won't ride the bus at all. I have no idea what their reasons might be, but this is the case for 40% of Minneapolis LRT riders. Further expansion of bus lines totally ignores this demographic. There is no way a bus line can ever be as well used as a train line.

Infrastructure
Infrastructure for a bus system deteriorates a lot more quickly that train tracks and such. Dedicated bus lines quite expensive to maintain, which at least partially mitigates the seemingly stunning cost savings for dedicated bus lanes. The cost advantage is clearly eliminated and then some by the other factors I have listed. For a large city trying to build a high capacity line like Minneapolis on University Avenue, there is no way bus transit in any form is cost effective compared to some sort of light rail.