The firm, which won the account after a five-way pitch, previously acted as Merseytravel’s legal adviser on the Mersey Tunnels Act 2004.
BDB public policy adviser Eoin Dardis said its four-strong comms team under the 42-strong parliamentary unit would work on the account, which is headed by BDB partner Jonathan Bracken.
The current Local Transport Plan is due to end next year, with the second beginning in 2006.
The firm will aim to raise awareness among the public and policy makers of Merseytravel’s attempts to improve public transport.
‘Local stakeholders are critical, but we have to ensure we talk to national stakeholders as well, including Whitehall, politicians and national opinion formers,’ said Dardis.
Merseytravel has responsibility for running the Mersey tunnels and ferries as well as organising rail and bus services across five local authorities.
Last year, it became the first public transport executive to win the right to appoint its own rail operator, handing a 25-year contract to the Nedrail consortium.
Concerns were raised in the summer that the authority might be scrapped if a North-West assembly went ahead, when deputy PM John Prescott suggested replacing it ‘made sense’.