The agency has been hired to communicate to passengers and staff details of the disruption on the firm's Bedford-to-Brighton line, which travels through central London.
The disruption, set to occur over the next two years, will be caused by engineering work aimed at creating an interchange for the Eurostar service at St Pancras station.
The agency won the account following a pitch organised by the Haystack Group, which initially involved as many as nine agencies (PRWeek, 31 January).
The QBO Bell Pottinger team, led by director Kevin Read, reports to communications director Martin Walter and commercial manager Peter Robinson.
Read said: 'No one wants to hear about this kind of thing, but it's important we let people know the details in advance so that it doesn't come as a shock.'
Disruption will include an extensive engineering works programme, due to start this October. However, disruption is set to increase after summer next year, when the through-London service, billed as the route's unique selling point, will be broken as part of the line closes completely for six months.
Read said it was important that passengers were aware that the work would result in a more efficient rail network in London, with better links to Europe.
- QBO Bell Pottinger was this week hired by Chelsea Village, the parent company of Chelsea Football Club, to handle consumer and B2B PR work. The brief includes promotion of the company's hotel, conference and banqueting facilities. QBO Bell Pottinger director David Wilson oversees the account.