Transmetro is one of the three bus systems that serve Guatemala City. It’s the newest, safest and most interesting.
Transmetro runs routes with dedicated stops. The stops are elevated as are the bus doors. Thus, no “just stop here” like with the other buses. Maned dedicated stops is what offers the security.
The Muni web site seems to hide information about Transmetro. For example, it is really hard to find the route map which is at https://rutastransmetro.muniguate.com/?c=Estacion&a=OnlyMap
It costs Q1 to travel on Transmetro. The stations now have an electronic payment system which works with “Vecino” cards and also regular credit/debit cards. Some of the bigger stations have machines to recharge the Vecino cards. Note that if you are “de la tercer edad” (old) you can get a special Vecino card to travel free. When I went to get mine they were out of them and I was told I could just show my DPI.