This market will resolve as YES if, by December 31, 2029:
Dar es Salaam has begun operation of a metro system, defined as a rapid transit rail system that operates on dedicated tracks either underground, elevated, or at grade level with complete separation from other traffic.
A system primarily promoted as "light rail" will count if I judge it to largely equivalent to a metro under the above definition, based on grade separation and dedicated rights of way.
A system primarily promoted as "commuter rail" or "regional rail" will not generally count, unless it is also referred to as a metro in official materials.
The system must be operational with at least one line and multiple stations serving the public.
Bus systems do not count as metro systems.
I will resolve this market using my judgement given the guidelines above. I will not bet on this market.