The New York times had an interesting article on the excessive congestion experienced by freight trains that try to cross the gridlock around Chicago. (“Freight Train Late? Blame Chicago“, May 2012)
Shippers complain that a load of freight can make its way from Los Angeles to Chicago in 48 hours, then take 30 hours to travel across the city. A recent trainload of sulfur took some 27 hours to pass through Chicago — an average speed of 1.13 miles per hour, or about a quarter the pace of many electric wheelchairs.
The utilization level of the existing infrastructure has gone up and is expected to go up even further. We know from queueing theory that as the utilization goes up, so does the average delay. Furthermore, the delay grows exponentially with the utilization level, which means that as the system becomes busier (,as the utilization approaches 100%), the delays become exceedingly high.
This issue is further exacerbated by the fact that the same rails are used for different types of traffic, with different priorities:
One of the biggest holdups for freight traffic is that Chicago’s crowded rails must also get hundreds of thousands of commuters to work and home mornings and evenings, and so by an agreement known as the Chicago Protocol, the shared tracks and intersections belong to passenger rail during rush hours.
This is hardly surprising: as the utilization increases, the situation becomes much worse for the low priority traffic. It is not that giving priorities to passenger trains that need to travel several times within a day and that have a more strict schedule, does not makes sense. It makes a lot of sense. It just means that the situations will become much worse for freight trains as the traffic volume increases, unless something is being done.
Given that the current capacity may be difficult to adjust, it seems that most of the effort to date involves improving the effective use of the current infrastructure by making sure that the different parties that use these rails are coordinated:
The resulting plan to fix its rail problems started with efforts to reduce delays by improving coordination among the six freight rail companies, an effort that includes Mr. Grewe, as well as Metra and Amtrak. “You would have thought that coordination would have taken place in the past,” Mr. Grewe said. “Unfortunately, it didn’t.
It is reassuring that we have already started to witness shorter delays. It is clear however, that in order to see a more meaningful reduction, and in order to prepare to the projected increase in volume, a more comprehensive network-wide solution is needed. But it seems that as more funds will be needed for such a comprehensive solution, we are going to hit another system in a gridlock: the legislative one.