Frankfurt Transport Authority (VGF) has exercised an option from an order placed in 2006 to acquire a further 78 Flexity Swift LRVs worth around €169m.
Forty of the 25m-long vehicles will be bi-directional, while the remaining 19 will operate in permanently-coupled pairs.
Deliveries will be completed by 2017, when all VGF vehicles built before 1990 will be withdrawn.
Meanwhile Essen Transport Authority (Evag) has awarded Bombardier a €72m contract for a fleet of 27 Flexity Classic LRVs.
Two pre-series vehicles are due to be delivered to Essen in August 2013, with delivery of the series-production vehicles scheduled to commence in March 2014.
Each three-section bi-directional LRV will be 30m long and 2.3m wide, providing capacity for 172 passengers.