Paris’s second-busiest commuter artery – the RER B – entered a 23-day partial closure at 05:00 on Saturday, severing the line between Gare du Nord and Bourg-la-Reine and throttling service to Charles-de-Gaulle (CDG) and Mitry-Claye. The works, part of Île-de-France Mobilités’ €4 billion summer modernisation programme, involve replacing 40 underground track switches and overhauling signalling software ahead of the 2027 rollout of new MI20 trains. During the 25 July-6 August phase, no trains will run through the historic “tronçon central”, forcing airport passengers to swap to replacement buses at Porte d’Orléans or detour via RER E and the fully automated Métro 14. Service north of Gare du Nord remains limited to one train every seven minutes, well below pre-pandemic frequencies. Operators warn of crowding at CDG terminals and advise travellers to allow an extra 45-60 minutes. Orlyval will be free for Navigo pass-holders during the works as partial compensation. The timing collides with France’s main holiday exodus and with tightened security controls around Paris for several high-profile events, amplifying the impact on business travellers. Airline crew-schedulers have flagged minimum-rest issues, while hotels near CDG expect a spike in “distress nights” as passengers miss late-evening flights. Ride-hailing platforms say driver demand is up 30 % along the A1 corridor, pushing surge prices towards record levels. For corporate mobility teams, the closure complicates airport transfers for short-term assignees and project teams cycling through headquarters. HR departments are issuing guidance to book flights arriving before 15:00 or after 22:00 when traffic is lighter, and to consider flying into Orly or regional hubs such as Lille-Lesquin with onward TGV connections. The engineering blitz is only the first of three RER B block-outs this summer; a second closure from 7 to 16 August will affect southbound branches. Employers with frequent flyers should therefore incorporate the altered timetable into travel-approval workflows through mid-August and review ground-transport allowances that assume a rail option to CDG.
