The busiest SNCF line in France is in Ile de France region. It is RER D with an average of 615,000
passengers daily in 2017(*). Traffic has grown 20% in the last 10 years and it continues to climb. Every day 450
trains operate on RER D across the northern and south eastern suburbs of Paris via the tunnel between Gare du Nord and Gare de Lyon. There are 59
stations along a route diagram of 197
km. Lets break that down;
In the south east division from Paris Gare de Lyon, the RER D network is arranged as follows:
- Gare de Lyon > Villeneuve-St-Georges (VSG) - 15 km / 4 intermediate stops
- VSG > Melun via Combs-la-Ville Quincy - 30 km / 9 intermediate stops
- VSG > Viry-Chatillon - 8 km / 2 intermediate stops incl. Juvisy
- Viry-Chatllon > Corbeil-Essonnes via Ris-Orangis (called the "Vallée" route) - 9 km / 3 stops
- Viry-Chatillon > Corbeil via Evry Centre (called the "Plateau" route) - 9 km / 4 stops
- Corbeil > Malesherbes (outer suburban line) - 45 km / 8 intermediate stops
- Corbeil > Melun (outer suburban line along Seine valley called "Littoral") - 25 km / 8 stops
TOTAL 141 km / 44 stations including the termini at Melun, Corbeil and Melesherbes
After the tunnel (5 km) via Chatelet, partly shared with RER B, the RER D line extends north from Paris Nord underground station to Creil - 51 km / 13 stops including intermediate termini at Villiers-le-Bel, Goussainville and Orry-la-Ville.
So, in total, 197 km (141+5+51), with 5 junctions (**) at Gare du Nord with RER B, at Chatelet with RER B, at Villeneuve St Georges :- Melun branch/Corbeil branch, Viry-Chatillon :- branch "Vallée"/branch "Plateau", Corbeil :- 4 way junction.
RER D services rotate via the tunnel between the termini in the south and in the north. 4 letter train codes identify the services. Typical services:
FACA : Melun - Goussainville, 87 minutes, 21 stops, 3 junctions
VUPE : Malesherbes - Villiers-le-Bel, 118 minutes, 25 stops, 5 junctions
SOVA : Corbeil - Creil, 111 minutes, 27 stops, 4 junctions
Punctuality on RER D is poor.The target of 92% on time has never been reached . In 2015, average punctuality was 86.3% but is much worse during the evening peak periods. In 2016, the result was 85.2%. Trains cancelled are not included in these statistics. Numerous trains are cancelled for technical failures, operating reasons ( a favourite excuse), accidents. One of the reasons for the poor results is the physical configuration of the network (lines are shared with other traffic, there are five junctions, the tunnel is a bottle neck). Delays from incidents cascade rapidly across the whole network. Incidents occur daily and severe disruptions arise several times a week. Delays are caused frequently by passengers (illness, suicides, vandalism, alarm signals pulled unecessarily, suspicious abandonned luggage). Incidents with the infrastructure can disrupt traffic for many hours - signal failures, overhead catenary, power failures. For more than 10 year an RER D blog (organised by users) catalogues travel problems on line as they happen.