Brass Birmingham's scoring for both eras creates a double-counting that rewards long-lived infrastructure. A cotton mill that scores in the canal era and again in the railway era has paid twice for its build cost. Building infrastructure with multi-era scoring potential is the game's highest-efficiency play.

The railway era resets the board by removing all canal-era buildings and links. Players who built high-scoring canal-era infrastructure begin the railway era with points already accumulated and their builds cleared for fresh placement. The transition creates a new map state that may be more or less favorable for each player's railway-era plans.

For Birmingham players focused on maximizing era-transition value: identify multi-era scoring buildings early in the canal era and prioritize them over single-era efficiency. A building that scores once is good. A building positioned to score twice is better.