To RER A, or to RER C? How Paris typifies the two models for cross-city commuter train lines

RER A, not quite in action. Image: Getty.

Since World War Two, some cities have sought to extend rapid transit into their suburbs by leveraging legacy commuter rail lines. Building on prewar examples from Berlin and Tokyo, they initiated a variety of treatments to modernise their commuter rail: electrification, integrated fares, high all-day frequency, and cross-city connections.

All this turns commuter rail into an express metro line. The city that has done the most in this direction is Paris, which since the 1970s has built a network called the RER, with five lines labeled A through E.

It is the cross-city connections that are the costliest to provide, since they almost always involve new tunnels under city center. Cities can build cross-city tunnels in two ways. One approach involves high investment: the tunnels are longer and involve several stations, often in difficult-to-construct locations. The main example is the RER A, whose construction involved about 17 km of new tunnel and seven underground stations, running on an east-west axis through central Paris.

The other approach is lower-investment: tunnels are the shortest possible connecting commuter rail terminals. The main example is the RER C, whose construction involved just 1 km of new tunnel and no new stations, creating an southeast-to-southwest line on the Left Bank of Paris.

A geographically accurate map of the RER network in central Paris. RER A is in red; RER C is in yellow. Image: Wikimedia Common.

This is a spectrum rather than a binary division: RER lines B, D, and E are intermediate between the high investment that went into the RER A and the low investment into the RER C. In layout, the RER B is quite similar to the RER A, but managed to leverage a legacy line reaching within 2 km of city center.

The same division between the two approaches holds outside Paris, too. In London, Thameslink is similar to the RER C, whereas Crossrail, with its long new tunnels, is like the RER A, as is the planned Crossrail 2. Berlin's North-South Tunnel from the 1930s, creating a new axis in the city complementing the older east-west Stadtbahn, is like the RER A.


North American projects, including the SEPTA Regional Rail tunnel in Philadelphia and the ongoing Toronto RER project, are both like the RER C. The Regional Rail tunnel connected two commuter rail terminals to create a mainline the shape of an inverted L, with some lines self-intersecting. Toronto is fortunate enough not to need new tunnels at all, since all commuter lines serve Union Station, some coming from the east and some from the west.

The main benefit of the RER C style is that it is much cheaper. It involves less tunneling, and the city can choose to build fewer stations. When tunneling deep underground, the stations are the most expensive element: for example, in New York's Second Avenue Subway, built deep to avoid street disruption, the tunnels cost $415m whereas the three new stations cost $2.2bn total. The central segment of the RER A cost about 5bn francs, corresponding to about €600m per kilometer in 2016 prices; no other rail tunnel in the world has cost so much except some New York lines and Crossrail. Crossrail, the other major modern example of this type of construction, is even costlier, perhaps £750m per kilometer.

The main benefit of the RER A style is that it lets commuter rail act as an express metro line. Such tunnels do not follow the shortest path between legacy terminals: both the RER A and Crossrail were designed as express east-west lines through city center, with stations connecting to most intersecting Metro or Underground lines. And they are not just commuter rail schemes but also relief lines for the busiest metro lines, namely Metro Line 1 and the Central line. RER C-style lines do not necessarily provide this: the RER C is parallel to Metro Line 10, the least busy in Paris.

Another metro-like property of the RER A is that it has a long trunk segment providing high frequency. This is also true of the RER C, but not necessarily of other RER C-style lines elsewhere. Thameslink's shared trunk is short, just between King's Cross and Blackfriars, and SEPTA's trunk is only a few kilometers long. This happens when a short tunnel connects to many commuter rail branches.

Evidently, the RER A style leads to higher ridership: current ridership on the RER A is about 1.1m per weekday (see page 24 of this PDF); that on the RER C only 540,000. This is despite the fact that the sprawling, many-branched RER C is almost twice as long as the RER A.

The proposed New York-New Jersey Crossrail.

In North America, proposed regional rail modernisation projects fall on the RER C side. In New York, the Regional Plan Association has proposed using the planned new tunnels under the Hudson River to build a New York-New Jersey Crossrail project. The RPA is not planning on any new stations to connect to subway lines that have no connections to the existing Penn Station.

And in Chicago, the Midwest High-Speed Rail Association has proposed reactivating through-tracks at Union Station to create a Crossrail Chicago. The plan only includes one new urban station and has no transfers to the busiest L lines. In both cases, the Crossrail name does not imply service levels comparable to Crossrail: the routes are awkward, kludged together from the available commuter rail lines.

In Boston, plans for the North-South Rail Link are more mixed. This project would provide new tunnels connecting the city's two rail terminals, North Station and South Station, which are about 2 km apart. One RER A-style feature of the plan is that, in addition to these two stations, there are plans for one intermediate station, called Central Station (Boston's central business district stretches roughly from South Station to the planned new station). North and South Station together connect to three of Boston's four subway lines, and Central Station would connect to the fourth.

The proposed Boston North-South Link.

For a city planning to modernise its commuter rail network with new tunnels for through-running, there are merits to both models: evidently, Paris built the RER C and not just the RER A. However, it is a mistake to assume that short tunnels could provide the benefits of the RER A or Crossrail. In New York and Chicago, if there are plans to through-run trains, their respective transit agencies should at least consider adding stations to intersect more subway or L lines, or even the busiest bus corridors. For example, New York could open a commuter rail station at Astoria and, when the new Hudson tunnels are built, at Bergenline Avenue. Toronto is fortunate not to need tunnels, but it should consider adding infill urban stops on the planned RER to relieve the city's two main subway lines.

The biggest cities should probably plan on at least one RER A-style commuter line. London came to this conclusion when it began the Crossrail program; despite the high cost, it is now very likely to build Crossrail 2. The largest North American cities should learn from this and consider some truly metro-like commuter lines rather than just lines in the mold of the RER C.

Alon Levy blogs at Pedestrian Observations and tweets as @alon_levy.

Want more of this stuff? Follow CityMetric on Twitter or Facebook.

 
 
 
 

The Thessaloniki dig problem: How can Greece build anything when it’s swarming with archaeologists?

Archaeological finds on display in an Athens metro station. Image: Gary Hartley.

It’s fair to say that the ancient isn’t much of a novelty in Greece. Almost every building site quickly becomes an archaeological site – it’s hard to spin a tight 360 in Athens without a reminder of ancient civilisation, even where the city is at its ugliest.

The country’s modern cities, recent interlopers above the topsoil, serve as fascinating grounds for debates that are not just about protecting the ancient, but what exactly to do with it once it’s been protected.

The matter-of-fact presentation that comes with the many, many discoveries illustrates the point. Athens often opts to display things more or less where they were found, making metro stations a network of museums that would probably take pride of place in most other capitals. If you’re into the casual presentation of the evocative, it doesn’t get much better than the toy dog on wheels in Acropolis station.

That’s not even close to the extent of what’s available to cast an eye over as you go about your day. There are ruins just inside the city centre’s flagship Zara store, visible through the glass floor and fringed by clothes racks; Roman baths next to a park cafe; an ancient road and cemetery in an under-used square near Omonia, the city’s down-at-heel centre point.

Ruins in Zara. Image: Gary Hartley.

There is undoubtedly something special about stumbling upon the beauty of the Ancients more or less where it’s always been, rather than over-curated and corralled into purpose-built spaces, beside postcards for sale. Not that there isn’t plenty of that approach too – but Greece offers such sheer abundance that you’ll always get at least part of the history of the people, offered up for the people, with no charge attached.

While the archaic and the modern can sit side by side with grace and charm, economic pressures are raising an altogether more gritty side to the balancing act. The hard press of international lenders for the commercialisation and privatisation of Greek assets is perhaps the combustible issue of the moment – but archaeology is proving something of a brake on the speed of the great sell-off.

The latest case in point is the development of Elliniko – a site where the city’s decrepit former airport and a good portion of the 2004 Olympic Games complex sits, along the coastal stretch dubbed the Athens Riviera. With support from China and Abu Dhabi, luxury hotels and apartments, malls and a wholesale re-landscaping of several square kilometres of coastline are planned.

By all accounts the bulldozers are ready to roll, but when a whole city’s hovering above its classical roots, getting an international, multi-faceted construction job off the ground promises to be tricky – even when it’s worth €8bn.


And so it’s proved. After much political push and shove over the last few weeks, 30 hectares of the 620-hectare plot have now been declared of historical interest by the country’s Central Archaeological Council. This probably means the development will continue, but only after considerable delays, and under the watchful eye of archaeologists.

It would be too easy to create a magical-realist fantasy of the Ancient Greeks counterpunching against the attacks of unrestrained capital. The truth is, even infrastructure projects funded with domestic public money run into the scowling spirits of history.

Thessaloniki’s Metro system, due for completion next year, has proved to be a series of profound accidental excavations – or, in the immortal words of the boss of Attiko Metro A.E., the company in charge of the project, “problems of the past”.

The most wonderful such ‘problem’ to be revealed is the Decumanus Maximus, the main avenue of the Byzantine city – complete with only the world’s second example of a square paved with marble. Add to that hundreds of thousands of artefacts, including incredibly well-preserved jewellery, and you’ve a hell of a haul.

Once again, the solution that everyone has finally agreed on is to emulate the Athens approach – making museums of the new metro stations. (Things have moved on from early suggestions that finds should be removed and stored at an ex-army camp miles from where they were unearthed.)

There are other problems. Government departments have laid off many of their experts, and the number of archaeologists employed at sites of interest has been minimised. Non-profit organisations have had their own financial struggles. All of this has aroused international as well as local concern, a case in point being the U.S. government’s renewal of Memorandums of Understanding with the Greek state in recent years over protection of “cultural property”.

But cuts in Greece are hardly a new thing: lack of government funding has become almost accepted across society. And when an obvious target for ire recedes, the public often needs to find a new one.

Roman baths in Athens. Image: Gary Hartley.

Archaeologists are increasingly finding themselves to be that target – and in the midst of high-stakes projects, it’s extremely hard to win an argument. If they rush an excavation to allow the quickest possible completion, they’re seen as reckless. If they need more time, they’re blamed for holding up progress. 

Another widely-told but possibly-apocryphal tale illustrates this current problem. During the construction of the Athens Metro, a construction worker was so frustrated by the perceived dawdling of archaeologists that he bought a cheap imitation amphora in a gift shop, smashed it up and scattered the fragments on site. The worthless pieces were painstakingly removed and analysed.

True or not, does this tale really prove any point about archaeologists? Not really. They’re generally a pragmatic bunch, simply wanting to keep relics intact and not get too embroiled in messy public debates.

It also doesn’t truly reflect mainstream attitudes to cultural capital. By and large, it’s highly valued for its own sake here. And while discoveries and delays may be ripe for satire, having history’s hoard on your doorstep offers inconveniences worth enduring. It’s also recognised that, since tourists are not just here for the blue skies, good food and beaches, it’s an important money-maker.

Nonetheless, glass malls and shiny towers with coastal views rising from public land are good for the purse, too – and the gains are more immediate. As the Greek state continues its relentless quest for inward investment, tensions are all but guaranteed in the coming years. 

This is a country that has seen so many epic battles in its time it has become a thing of cliché and oiled-up Hollywood depiction. But the latest struggle, between rapacious modernity and the buried past, could well be the most telling yet. 

Want more of this stuff? Follow CityMetric on Twitter or Facebook