The recently introduced VayVen  bus network has markedly improved public transport in Mérida. The large blue buses are modern, air-conditioned and quiet. They can, in theory at least, be tracked using an app. The app is an asset but still has some issues which hopefully can be resolved over time. The fares are 33% more (12 v 9  pesos) than the older buses but you may find that 3 pesos is a small price to pay to avoid having your back drenched in sweat after a scorching bus ride.. The routes are expanding and at present most of the main arterial routes to the periferico are covered. The buses also have front racks to carry up to two bikes at no additional charge. Several of the routes also have a night service that runs until about 3am.  The signs for bus stops are  a marked improvement from before when bus stops were often a matter of guesswork between driver and rider. The blue bus often do not have route numbers assigned to them and so it is possible to be waiting for a bus just for it to pass by without stopping if it is from another route. Often buses cannot stop exactly at the bus stop because the stop is occupied by parked traffic vehicle and little to no enforcement by the authorities.  Overall the system has a way to go but is better than before and heading in the right direction.