Germany and Summer Maintenance
I’ve been looking at some intercity rail trips in Germany for later this summer, and was reminded of how nonfunctional the system is this season. I was asked specifically about Cologne-Frankfurt trips, and discovered that for later this month, they’re timetabled to take 2.5 hours. These cities are 180 km apart on the high-speed line, where trains normally take a little longer than an hour, but right now the trains don’t seem to be using the line – rather, they’re on the classical line, which follows the Rhine and is not at all fast. This is not the only line or the only summer that this is happening; since I moved to Germany, my summer travel plans have been constrained by these seasonal slowdowns, and between them and the mediocre average speed of most German intercity lines, I’ve forgone trips I would have made at French speeds and reliability. The rationale for these summer closures for maintenance is wholly without merit on intercity rail, and this practice holds back rail travel at the time when demand is highest. Deutsche Bahn should cease this practice and instead do like neighbors with year-round intercity rail travel.
Why?
Rail lines must have regular closures for maintenance. The norm is that this is done overnight, on both urban rail and mainline rail. However, overnight closures are sometimes supplemented by daytime closures, especially for longer-term renewal; daytime closures are especially common on lines that don’t close overnight at all. Readers from New York with its 24/7 service are all too familiar with weekend service changes, which may shut down entire line segments and direct riders to alternative routes. German U-Bahns don’t run 24/7, but do run overnight on weekends, so there are only five nights of maintenance windows and not seven. New York-style weekend closures are not common in Berlin, but occasionally some segments are shut, though in my experience it’s more common on the S-Bahn.
To be clear, there are good and bad reasons to engage in daytime shutdowns. Long maintenance windows allow higher productivity, so agencies prefer them when they can get away with them. The balance of when agencies and rail companies use daytime maintenance windows depends on all of the following factors:
- Traffic: daytime shutdowns are used more often during less busy times – for example, RATP uses them in the summer, when everyone is on vacation and so Métro traffic is reduced.
- Redundancy: systems on which passengers can bypass closed sections, such as the New York City Subway or the German national rail networks, can reroute passengers onto alternatives, which does not eliminate the cost to passengers of the closure but does reduce it. RATP also uses the redundancy of the Métro with the RER to do summertime shutdowns and tells passengers to transfer.
- Single-tracking options: this is specific to weekend closures rather than longer-term ones, but, if the system is set up in a way that permits trains to single-track around obstacles, which is common in twin-bore tunnels, then weekend closures are rather easy. The Copenhagen Metro’s combination of twin-bore tunneling and driverless operations permits single-tracking even overnight, permitting 24/7 service without weekend service changes.
- Agency culture: some agencies are just more accepting of disruptions than others. MBTA insiders insist to me that concrete curing requires weekend shutdowns, often of multiple lines at once, even though Boston has regular nighttime shutdowns; evidently, Japanese subways manage to run without this.
The situation of German intercity rail
Germany uses long-term shutdowns, measured in months, to do rail infrastructure renewal. These are usually in the summer, because, in Germany as in Paris, this is vacation season and therefore people are less likely to be going to work. The national network here is highly redundant, and intensive summertime shutdowns slow down passengers but do not make trips literally impossible: the Cologne-Frankfurt work is evidently adding about 1.5 hours to trips, and work previously done on the Frankfurt-Mannheim line slowed passengers by about 40 minutes (while still permitting some timed connections); in contrast, unscheduled breakdowns on the Northeast Corridor due to summer heat lead to trip cancellations.
The stupid thing about this is that while summer vacation travel reduces demand on urban rail, it has the opposite effect on intercity rail. The summer is consistently high season for intercity travel, precisely because it’s when people take vacations. In France, at least on domestic TGVs, fast trains are in plenty. But not here – instead, the trains are the least likely to be running, due to maintenance.
Much of the problem is that, unlike Shinkansen lines and LGVs, most German high-speed lines do not have regular nighttime closure windows. They run mixed traffic – passenger trains during the day, freight trains during the night. This feature allows for more flexibility of freight rail, but raises the construction and maintenance costs. Mixed lines must be built with freight-friendly features including gentler grades and lower superelevation (see explanation for superelevation here), the latter requiring wider curves to allow high speeds on passenger trains; both features require more tunneling, and as a result, German high-speed lines are much tunnel-heavier than French ones, raising costs. Maintenance is more difficult as well due to the lack of regular nighttime shutdowns.
That said, the Cologne-Frankfurt line is not a mixed line. It’s a passenger-only line, with a ruling grade of 4%, higher than any other high-speed line I know of (LGVs use 3.5%). It also has the tightest curves I know of on newly-built high-speed lines relative to speed, running at 300 km/h on 3.35 km radius curves, a lateral acceleration in the horizontal plane of 2.07 m/s^2; only the Shinkansen has faster lateral acceleration, and that’s on older lines running tilting trains. Consequently, it’s actually the least tunnel-heavy of the German high-speed lines. Nonetheless, it evidently does not run every day, every year, the way LGVs and Shinkansen lines do.
This is where I suspect agency culture comes into play. American cities other than New York and to some extent Chicago shut down their subway systems overnight, but still force passengers onto bus diversions on weekends for maintenance, where their foreign counterparts do no such thing; this has to be understood as a combination of managers not really caring about weekend service (leading to lower base frequency as well) and comparing themselves to New York even without 24/7 service. In Germany, the culture is that high-speed lines should be built to mixed standards, even if they are useless for freight, for political reasons, and renewal should consequently be done in long-term shutdowns with accelerated work, and this culture is evidently also affecting a line that is built to passenger-only standards. This may also be compounding with the European culture of summer vacations, leading to reduced urban rail service during summers – I am not sure, having seen explicit service reductions in Paris and Stockholm but not here.
Conclusion
Long-term closures have tradeoffs. In some cases they are legitimate, especially when the time cost to passengers is greatly reduced and when traffic is lower. However, neither of these two conditions applies in the case of intercity rail traffic in Germany. The closures are happening during the busiest time of intercity travel, and delaying passengers by an hour or even more. Worse, this practice is used not just on mixed lines like Hanover-Würzburg but also on passenger-dedicated Cologne-Frankfurt, which has regular nighttime work windows. When the reason for the closures is cultural, it ceases to be legitimate; it instead points out to an agency that refuses to think outside of its box, and will not assimilate better practices from elsewhere.



