Category: Freight

Followup on the Providence Regional Rail Shuttle

Peter Brassard’s proposal for a very frequent-stop mainline train in Rhode Island received comments both here and on Greater City, dealing with issues from rolling stock to station choice to scheduling. Some are fairly trivial, some aren’t. The upshot is that the project is technically feasible, but requires political head-bashing, especially with regards to scheduling.

First, the easy part: if the line is only to run between Central Falls and Warwick, then the rolling stock should be electric; this both improves performance and eliminates a political bottleneck, because the EMU market is larger than the DMU market, and in case FRA regulations do not change and obtaining a waiver is too expensive, there are M8s ready to use. The M8s are heavier than is ideal, but their performance is to my knowledge imperceptibly worse than that of noncompliant trains in the speed range appropriate for the short stop spacing, up to about 100 km/h.

Scheduling is the problem, because there has to be track sharing with something. The line is three-tracked: there are two tracks for Amtrak, also used by the MBTA north of Providence Station, and one track for freight. The line used to be four-tracked, but was reduced to three tracks in the 1990s in order to widen the track centers and allow the Acelas to tilt. Further reduction in track centers is not acceptable: at 4 meters (more precisely 13′) the distance is shorter than the standards for greenfield construction in Europe and even Japan. Track center standards are laxer on lower-speed segments, as the trackage through Providence is, but tilting becomes unsafe for an Acela-wide train. (The Pendolino is 37 cm narrower than the Acela.)

The alternative is to slightly widen the right-of-way at certain overpasses to allow four tracks, for a minimum of 20 meters with 4-meter track centers; some work, including widening, is already required to make room for platforms, and many of the most constrained locations, such as Olneyville at 18 meters, are station stop sites. It’s this construction that would most likely be the bulk of the project cost. At much lower cost, it would also allow electrification of the full corridor, making EMUs a feasible rolling stock choice for the local trains.

With four tracks, the question becomes, what regional rail should share tracks with. The choice is between intercity trains, which are currently slow but could be sped up, and freight trains. Both require political maneuvering, because neither Amtrak nor the Providence and Worcester has operating practices that are compatible with punctual passenger service. (Amtrak is more easily reformable, but an Amtrak that’s been so reformed is an Amtrak that runs trains much faster on the Northeast Corridor, increasing the regional/intercity speed difference).

I contend that it’s actually more correct to share tracks with freight. The sharpest curves are at stations, and so no superelevation is needed, but even if it were, allowing 100 km/h passenger trains could be accommodated with minimal freight train cant excess (about 25 mm at 50 km/h). More importantly, freight and local passenger rail have similar average speeds. The speed profile is different – freight is steady and slow, local passenger rail attains higher speeds but makes frequent stops – but when headways are long enough, this is not a problem.

On page 46 of the Providence Foundation study on a similar passenger line, we see that there aren’t many freight trains, so headways are determined by passenger trains. The freight schedule on page 48 of the same study suggests that freight and passenger train speeds would be very similar. It has trains doing Pawtucket-Warwick in 23 minutes; modern EMUs with a top speed of 100 km/h (losing 45 seconds to each station stop) and making the proposed stops would do the same in 25 minutes, with 7% padding. The local passenger train is a hair faster than the freight train on the Providence-Pawtucket and Cranston-Warwick segments, in both cases by less than a minute, and a bit slower on the Providence-Cranston segment, where station spacing is denser. This is close enough that I believe that 15-minute passenger train frequency is no barrier to track sharing. Potentially even 10-minute frequency can be accommodated. It requires freight trains to be somewhat timetabled, but they’d have a window of several minutes to enter between each pair of successive passenger trains, and missing their window would not delay them by more than 15 minutes. There is, then, no technical barrier to sharing tracks with freight.

The alternative, sharing tracks with intercity trains, is more dubious. Although less construction is required, the speed difference is larger. Instead of taking 23 minutes between Pawtucket and the airport, optimized intercity trains would take 8:45, including padding and a station stop at Providence. They can pass local trains at Providence, at the cost of slowing them down by several minutes while they wait to be overtaken, but even between Providence and the airport, travel time would be 5 minutes for intercity trains and 17 for regional trains.

If there’s four-tracking in Warwick, or two stops are dropped, then it’s tight but doable. Otherwise, it’s not; 12 minutes is too long a window for 15-minute service. It would require an extra terminating track at Warwick, but that would be needed anyway. The problem then is that local Rhode Island trains and MBTA trains would interfere with each other at Providence because both would dwell at the station for too long.

Interlining the two services and having MBTA trains make local stops in Providence is possible, and in conjunction with the two-overtake schedule for Boston-Providence naturally yields a three-overtake schedule. The problem is that the more overtakes there are the more reliability suffers. If an hourly freight train misses a window and needs to be delayed 15 minutes, it’s no big deal; if the goods couldn’t take a 15-minute delay, the train would be sufficiently punctual to make the window. If a passenger train misses a window, it requires the train behind it to slow down and this is not recoverable if the schedule is so tight.

When it’s unavoidable it’s best to just invest in running trains on schedule, but in this case a three-overtake schedule is avoidable. Thus track-sharing with freight is the correct option, leaving intercity trains to have a track that’s entirely theirs south of Providence, as this shuttle concept would almost certainly take over Wickford Junction service if necessary. It conveniently also allows higher regional rail frequency should the need ever arise, and because the scheduling is loose makes it easier to shoehorn another line into this system.

The Cost of Heavy Freight Trains

Over at Pennsylvania HSR, Samuel Walker reminds us that the dominance of coal for US freight traffic slows down passenger trains, and this has a social cost in addition to the direct costs of coal mining and burning. But another post of his, regarding cant deficiency, suggests more problems coming from mixing modern passenger trains with very heavy freight. Coal trains slow all other traffic in three different ways, of which just one is the conventional schedule conflict, and even that means more than just slowing down intercity trains.

Schedule conflict reduces not just speed, but also span and punctuality. The Northstar Line in Minnesota shares track with BNSF’s Northern Transcon; since the line is freight-primary, there’s no room for off-peak service, and passenger trains can’t extend to the line’s natural terminus in St. Cloud, not without constructing additional tracks. Similarly, in Houston, plans for a commuter line to Galveston included peak-only service from the start.

Second, independently of scheduling, slow trains force faster trains to slow down by limiting the amount of superelevation that can be used. As a reminder: on curves, they bank the track, with the outer rail above the inner rail, to partly counter centrifugal force. If they do not cant the train enough, there’s cant deficiency; if they cant too much, there’s cant excess. Although there are strict limits for cant excess (in Sweden, 100 mm, or 70 on tighter curves), stricter than for cant deficiency (150 mm for a non-tilting passenger train, give or take), technically commuter trains could safely run at higher cant excess; however, for freight trains, high cant excess is unsafe because loads could shift, and the higher axle load means trains would chew up the inner track. Very heavy trains first require the track to have a lower minimum speed, and second have an even more limited cant excess because of the damage they’d cause to the track (about 2″, or 50 mm, in US practice). Walker links to a US standard guideline that uniformly assumes 3″ cant; greenfield high-speed lines go up to 180-200 mm.

And third, heavy freight trains damage tracks regardless. Coal trains also limit the amount of revenue the railroad gets out of each train, leaving limited money for maintenance, and are not time-sensitive, giving railroads no reason to perform adequate maintenance. To compensate, industry practices have to be less than perfect: cant and cant deficiency are less than the maximum permitted by right-of-way geometry and minimum speed, and freight railroads require barriers between their track and passenger track to protect from inevitable freight derailments. Even then the US safety level is well below what’s achieved anywhere else in the world with trustworthy statistics.

Of course, coal provides a great boon to the freight railroads. It’s a captive market. The railroads could price out coal and focus on higher-value intermodal traffic. Some of the lines that already focus on intermodal traffic are friendlier to passenger service, such as the FEC.

However, realistically, the end of coal is only going to come from environmental regulations. Those same regulations would apply to oil, inducing a mode shift from trucks to rail. The coal trains that would stop running would be replaced by trains carrying higher-value goods. The details depend on what the purpose and kind of environmental regulations are, but today’s environmental movement is heavily focused on climate change and not as concerned with local environmental justice, so loss of coal traffic due to a high carbon tax or local air pollution tax, both of which would also affect oil and gas, is much likelier than loss of coal traffic due to restrictions on mountaintop removal and air quality regulations at mining sites, which would not. (Of course oil causes plenty of damage to the biosphere, but the mainstream environmental movement is much more concerned with effects on humans than on other organisms.)

The political issue at hand, besides the easy to explain but hard to implement matter of avoiding catastrophic climate change, is what freight railroads are used to. Their entire business model is geared toward relatively low-value goods. A steep carbon tax is a risk: it should raise their mode share of total value of goods transported, which is currently 4% (see also figure 4.3 here), but it would come from a new set of goods, with requirements and challenges different from those of the current mix. The railroads would have to reintroduce fast freight, which most haven’t run in decades, and refine it to deal with the needs of shippers today. It’s not only a headache for the managers, but also a substantial risk of failure – perhaps rival railroads would be able to get all the traffic because they’d adapt to the new market faster, perhaps shippers would change their factory placement to move goods over shorter distances, perhaps they would not be able to cope with the immediate increase in fuel costs, etc.

Because of this, freight railroads may end up fighting a policy that would most likely benefit them. Although they represent a critical part of an emission reduction strategy, and are all too happy to point out that they consume much less fuel than trucks, fuel is a major cost to them, and coal is big business for them. These are not tech startups; these are conservative businesses that go back to the 19th century. Heavy coal trains then add a political cost as well: they help turn an industry that could be a major supporter of climate change legislation neutral or hostile to the idea.

Quick Note on Food Transportation

It’s a commonplace among some environmentalists that an oil- or carbon-constrained world is one where it’s prohibitively expensive to ship food long distances, and therefore people should eat local. For example, James Kunstler argues that cities will shrink and people will return to locally grown agriculture. For the benefit of society, let me debunk this fantasy with some hard numbers.

Suppose the price of diesel rises by $20 per gallon – $5.25 per liter. This is somewhat higher than the E3 Network‘s 95th-percentile estimate for the economically correct carbon tax in 2050, and twice as high as the estimate for 2010. It could come about due to an apocalyptic oil shock, though such a world and a world with a very high carbon tax are mutually exclusive. Today’s Class I freight trains are capable of moving about 450 short tons of freight one mile on one gallon of diesel – about 170 ton-km per liter. (Large cargo ships are about equally efficient, so this holds equally well over oceans.)

Let’s now look at rice, a very cheap retail food item that can’t be grown in every climate and is thus vulnerable to an increase in price that’s essentially constant per unit of weight. Under the above assumptions, shipping rice from Arkansas to New York, a distance of about 2,000 km, would require an extra $60 per ton. The actual retail price of rice in the US is around $1,700 per ton, so the oil shock would raise the price of transporting rice long-distance about 3.5%. First- and last-mile transportation at both ends uses trucks and would become much more expensive, but this would be equally true of long-distance food shipping and locally grown food.

This actually overstates the supposed problem of shipping food across regions, because high fuel prices lead to both higher efficiency and lower consumption. In 2009 BNSF said it would take $10 billion to electrify its mainline network, including purchasing dual-mode locomotives, and pegged the breakeven point for such a venture at $4/gallon gas. A carbon tax would also cause the source of such electricity to shift to greener sources than coal.

While locavores insist on shaving off the small, small portion of their carbon footprint coming from food transportation, many ignore the much larger issue of what they eat. Not all – the environmental movement is full of vegetarians – but the attitude that buying local is more helpful to the environment than avoiding red meat is sufficiently widespread that it’s important to note that the opposite is the truth.

Everyone should read the study linked in the above paragraph. Even when accounting for the full transportation cycle of food, including fertilizer and other materials, transportation is a small percentage of food emissions. Ruminant animals emit large quantities of methane; large mammals hog feed and thus require more fertilizer and energy to grow; manure adds more emissions of nitrous oxides and methane. As a result, red meat consumed in the US emits 22.1 kg-equivalent of CO2 per kg. The average carbon cost posited by E3 – $400 per ton, one fifth the apocalyptic amount used in the rice transportation calculation – would tax red meat $9 per kg, $4 per pound, roughly doubling its retail price.

New York-Area Track Maps

The original purpose of this blog was to give me a domain name to upload things related to transit. The resource I was uploading was track maps of the New York area due to Rich E Green, whose site unexpectedly vanished last month without caching the maps on Google. Here are the maps I’d saved or gotten from helpful commenters:

NEC in Maryland and DC

If you have any of the rest of the maps, please send them over so that I can make them publicly available again.

Update: all links scrubbed 12/7 by the author’s request, due to copyright issues.