NRC study on transporting ocean containers inland

[I was interested in this research because if trucks can’t be electrified, civilization ends (see “When Trucks Stop Running: Energy and the future of Civilization” (Springer 2015)). 

This paper doesn’t have a solution to getting containers from ports to inland distribution centers, but discusses the pros and cons of all the possible solutions. Electrified trucks (battery or catenary) are preferred, but not technologically ready yet, and fixed-guideway systems are the worst possible solution for so many reasons I stopped listing them.  Alice Friedemann ]

NRC. 2015. Evaluating alternatives for Landside Transport of Ocean Containers. National Academies Press. 171 pages.

Based on the available information supplemented by the research team’s analysis estimation and conceptual design efforts, advanced-technology fixed-guideway systems (e.g., Maglev, linear induction motor (LIM), and linear synchronous motor (LSM) will not have an effective role in solving the ports’ inland container transport problems for the foreseeable future. Such systems do not appear to be cost-effective relative to either free-running truck drayage or battery-electric trucks with wayside power. The capital costs are substantially higher than the alternatives. The operating costs are likely to be prohibitive, eliminating any potential for substantial diversion of trucks from existing streets or highways.


The proposed evaluation method yields the same end result as the Roadmap analysis and the I-710 Alternatives Analysis: advanced fixed-guideway systems are too costly, too narrow in their application, too inflexible, and insufficiently scalable to be cost-effective solutions to the emissions, congestion, and capacity problems facing the Ports and the region. Moreover, the very long and uncertain lead time for their development and implementation would leave pressing problems unaddressed for an unacceptably long time and entail considerable risk.

  • Automated small-vehicle fixed-guideway technologies are inherently unsuited to moving large volumes of marine containers in complex or multi-destination networks. These technologies excel at handling passengers in relatively short, simple loops or systems.
  • Advanced fixed-guideway systems are inherently capital-intensive, especially where they must be elevated and retrofit to legacy facilities.
  • Advanced fixed-guideway systems are inherently inflexible and non-scalable compared to truck drayage systems.

The current social, environmental, and economic context of North American ports requires that a transport system do more than move containers efficiently.

The advanced propulsion systems remain largely conceptual in their application to container transport, despite some successful demonstrations under “laboratory” conditions. There is no obvious source for ongoing research and development beyond the private capital of the proponent firms, so the outlook for eventual technological and system readiness is unclear.

Throughput Capacity

Passenger rail transit is typically viewed as a high-capacity alternative to highways. Transit trains of 10 cars with 150 passengers in each operating on 5-minute headways can move 18,000 passengers an hour over a single track. By comparison, a lane of highway with 1,200 vehicles per hour on 3-second headways with 1.7 occupants in each moves just 2,040 passengers per hour.

The calculation, however, changes radically when the system is moving containers. Single container vehicles moving at 60-second headways (the usual proposed interval) over a fixed-guideway can handle just 60 containers per hour. The highest proposed capacity for a fixed-guideway system is for 10-container vehicle consists at 90-second headways, or 400 containers per hour. It is not certain that such an operation is at all feasible, given the stopping distance required by an 800,000-pound consist of 10 fully loaded containers. Moreover, such an approach begins to resemble a conventional railroad rather than an advanced container mover technology.

A lane of freeway can handle 1,200 containers per hour on trucks traveling at 3-second headways. This comparison leads to the ironic observation that if right-of-way is available for a new system, capacity would be maximized by paving it for trucks.

The ability of fixed-guideway technologies to actually deliver those capacities in practice is questionable and has yet to be demonstrated in a realistic port environment. ISO containers weigh a minimum of about 5,000 lb empty and a maximum of around 80,000 lb loaded, equivalent to 500 160-lb passengers. A single-container vehicle must therefore be capable of supporting, accelerating, and stopping a load equivalent to 3 to 5 loaded transit cars. It may not be possible to do so safely on 1-minute headways, particularly at the speeds often claimed for advanced technology systems. At a minimum, the container vehicles would need to be far more robust than transit vehicles, with adverse implications for weight and cost. The tight headways might also be compromised by the need to allow for vehicle exit and entry in multi-terminal system configurations.

The capacities of highways can be equaled by fixed-guideway systems when such systems resemble conventional railroads. A conventional train of 32 five-unit double-stack container cars can carry 320 40-foot containers. On 15-minute headways, such trains can move 1,280 containers per hour, equivalent to trucks on a freeway lane. However, it typically takes at least 4 hours to unload and reload a full double-stack train on each end of the trip, at a cost of $30 to $50 per container move. Such operations are therefore only practical and competitive over much longer distances than are considered here (e.g., a minimum of 500 to 750 miles in most instances) to allow the loading and unloading time and cost to be spread over a greater distance traveled. There is also an implied need for large terminals capable of handling hundreds of containers and multiple trains.

Transit Time

The guideway technologies proposed are all drawn from passenger applications in which shorthaul transit time is very important and where the “cargo” is self-transferring. When applied to container transport, these technologies emphasize high speed and automation and, to date, largely ignore the need to load and unload the vehicles. High speed over short distances (under 100 miles) can be a priority when movement over the rail system constitutes the entire trip. A 100-mile trip at 30 to 35 mph over conventional roads can take 3 hours, whereas a 100 mph rail system can make the trip in an hour. The difference is likely to be of significant value to a passenger, especially one making a round trip. The 2-hour savings, however, is insignificant for a container making a 15-day, one-way trip between an Asian port and Chicago. The transit time issue recedes further in importance when the container is moving between an inbound vessel and a train scheduled for a fixed departure. As long as the container meets the railroad’s cut-off time for the train departure, reduced transit time is of no value.

Terminal Design and Container Transfer

A major limitation of fixed-guideway technologies in container transport is the loading/unloading function. The speed at which containers can be unloaded and reloaded on any transport vehicle is limited by the laws of physics. ISO containers weigh a maximum of around 80,000 lb loaded. Quick acceleration and braking of an 80,000 lb object would require massive force, with high likelihood of cargo damage and serious safety consequences. The largest quayside container cranes have a hoist speed of only about 4 feet per second (3 mph) with their rated container loads. Steady-state productivity for container cranes ranges from 20 to 30 moves/hour, or 2 to 3 minutes per move. Mobile lift equipment used in marine and rail intermodal terminals has a similar transfer rate. ISO containers can only be safely lifted from the top corner castings or supported on the bottom corner castings. They are not designed to be lifted, pushed, or pulled from other points. A complete lift-off/lift-on cycle consists of:

  • Positioning the lifting device over the inbound container on the vehicle
  • Locking the lifting device into the top corner castings
  • Releasing any attachments to the vehicle (e.g., bottom corner castings from a rail car or twist locks on a road chassis
  • Lifting the container clear of the vehicle
  • Transloading the container horizontally to the intended drop point or delivery vehicle
  • Lowering the container to the drop point or vehicle
  • Releasing the lift device from the top corner castings
  • Raising the lift device clear of the container
  • Positioning the lift device over the second (outbound) container
  • Lowering the lift device onto the top corner castings
  • Locking the lift device into the top corner castings
  • Lifting the container
  • Transloading the container horizontally over the outbound vehicle
  • Lowering the container onto the vehicle
  • Releasing the lift device
  • Raising the lift device clear of the container
  • Securing the outbound container to the vehicle

Assuming that both containers are ready to be transferred and located within reach of the lift equipment and that the drop location is adjacent and clear, the unload/load cycle takes a minimum of 5 to 6 minutes. To this must be added the time to shift the lift equipment between vehicles. These times are incompatible with headways of 1 to 2 minutes or less and imply that the vehicle must be taken off the line-haul guideway for loading and unloading. This observation means, in turn, that vehicles must be spaced far enough apart on that line-haul guideway to allow for other vehicles to enter and exit the stream. The problem quickly increases in complexity if there are multiple terminals on each end of the trip, such as at LA/LB.

The terminal operations also add capital and operating costs. Terminals are estimated to cost in the neighborhood of $250 million each. Comparable lift costs at rail intermodal terminals are typically $30 to $50 at high volumes, and $50 to $100 at lower volumes typical of the systems contemplated here. A lift-on at one end of a system and a lift-off at the other end would therefore cost $100 to $200 in addition to the one-way line-haul cost and any contribution to capital cost. By comparison, current (2014) round-trip truck drayage rates between the Ports of Los Angeles and Long Beach and the UP ICTF are $150 to $200.

Some proposals envision direct transfer between vessel and the fixed-guideway system. Although perhaps physically possible, such transfers are not practical. Bringing the fixedguideway system to the vessel side would be enormously disruptive to vessel operations. Efficient direct transfer assumes that vessel stowage has been arranged to suit, which is an untenable assumption given the realities of vessel stowage at foreign ports and multiple vessel calls. Moreover, the need for the terminal to sort both inbound and outbound containers requires a buffer in the system, supplied by the terminal container yard.

Utilization and Peaking

All of the advanced fixed-guideway technologies proposed to date implicitly anticipate continuous, automated operations of multiple vehicles on fixed headways. The throughput capacity of such systems is effectively a constant, i.e., 60 containers per hour for a single track with 1-minute headways between vehicles. Marine terminal container movements, however, display marked peaks and valleys in daily and weekly operations that appear poorly matched to the level capacity of proposed fixed-guideway systems. North American marine terminals typically operate a single day shift, e.g., 7AM–4PM or 8AM–5PM, with extended gate hours or additional shifts scheduled as required.

Finally, there are variations during the year, with agricultural movements and holiday goods creating seasonal peaks. This peak-and-valley variability creates difficulties for any fixed-capacity system:

  • A system capable of handling the peaks will be underutilized during the valleys.
  • A system sized to the valleys may be highly utilized at most times, but must be augmented with other systems during the peaks.
  • A system sized between the peaks and valleys will be alternately over-burdened and under-used.

These observations suggest that a fixed-capacity system will operate significantly below its steady-state design capacity over time, unless it comprises such a small share of port container volume that it can always be fully utilized regardless of trade fluctuations.

Flexibility and Scalability

Fixed-guideway systems are inherently less flexible and less scalable than truck drayage using public highways. Although port terminals are rarely moved, their configurations and boundaries can change over time and new ones are added with some regularity. The pattern of container movement can also change with shifting international trade patterns, development of inland rail terminals, or emergence of new transloading and distribution facility clusters. Ideally, a fixedguideway system (like a transit system) should act as a catalyst to such development, shaping the future rather than trying to react to it. Such a strategy is risky, however. Scalability is also an inherent problem with fixed infrastructure because it is “lumpy” in nature. That is, it must be built in complete and usable sections to be of any operational value. In addition, such systems are usually slow and costly to expand, reduce in size, or change in any meaningful way. Flexibility and scalability are especially salient issues in a changeable political environment, where new regulations, policy shifts, or other infrastructure projects can quickly change the economic and financial environments for better or worse.

[And many, many more problems with fixed-guideway systems. If you aren’t convinced by now, continue reading the original document ].


Truck Platooning

Truck platooning refers generally to methods for operating trucks in closely grouped sets, with the goal of reducing fuel and labor costs and increasing effective highway capacity. There are multiple concepts for truck platooning:

  • Electronically linked “trains” of trucks following a lead driver, exemplified by the European Safe Road Trains for the Environment (SARTRE) project or the Japanese Energy ITS project.
  • Ad hoc platooning of vehicle-to-vehicle linked trucks, exemplified by the Peloton system.

Platooned trucks with linked automatic braking system can travel closer together than unlinked vehicles because the reaction and braking time of the automated systems exceeds that of human drivers. The ability to travel closer together at high speeds results in less aerodynamic drag and thus greater fuel economy.

Results to date suggest that potential fuel savings may be in the range of 5–7% at highway speeds (e.g., 65 mph in recent tests). Demonstrations of the Peloton approach in 2013 and 2014 yielded fuel use reductions of 4–5% in the lead truck and 10% in the rear truck; about 7% on average. Because aerodynamic drag is a function of the square of the speed, however, fuel savings at the lower speeds typical of local and regional drayage would be far less.

Labor saving depends on the trailing trucks being driverless, which for safety reasons is only envisioned for closed-system, dedicated lane operations. For local and regional drayage, driverless trucks would be impractical. The only potential application may be in container trips between a single marine terminal and a single off-dock rail terminal.

The ability to operate trucks closer together (e.g., 10 meters apart at 65 mph) is also less important at lower speeds where trucks are already closely spaced. The ability of platooning to increase net capacity is therefore extremely limited. Research for Caltrans under the PATH project found that gains by platooned long-haul trucks were achieved at the expense of short-haul trucks (which would include most drayage) and passenger vehicles. The research team did not treat truck platooning as a separate candidate container transport technology for the following reasons:

  • Overall, progress to date on the truck platooning concept suggests that it would be most effective at higher speeds and on longer trips than are typical of local and regional truck drayage or container distribution.
  • If implemented on exclusive rights-of-way, truck platooning features such as automatic gap adjustment and braking could become part of the guideway and propulsion systems examined above. In the Southern California I-710 case, the electric drayage scenario included truck platooning capabilities.
  • If implemented in a vehicle-to-vehicle format, such as the Peloton demonstrations of 2013 and 2014, truck platooning would be a method of improving truck performance rather than a container transportation system per se.

Technological readiness

Although the electric wayside power and battery-electric truck technologies have been successfully implemented separately, it cannot be assumed that they would necessarily function together as a system in the port environment. It is envisioned that trucks would also recharge their batteries while receiving propulsive power from overhead catenary. The distances to the near-dock rail terminals, however, range from 4 to 6 miles from the marine terminals. At 30 mph, the time under catenary would be just 8 to 12 minutes, which is far less than required to charge or even “top off” truck batteries. Significant additional technology development would be required to determine how far or how long a truck would need to travel with wayside power to accumulate enough battery charge for significant “off-wire” travel.

Battery-Powered Trucks

Battery trucks are, so far, restricted to either light-duty or in-terminal operations and do not yet have the storage capacity for routine use in port container drayage. Although this technology is expected to progress and improve, the capacity limits of battery trucks are a major factor in developing wayside power options. The Ports of Los Angeles and Long Beach are also funding the demonstration of a battery-powered heavy-duty truck. Except for propulsion, the vehicle is otherwise ordinary and can use legacy streets and highways as well as marine, rail, and customer facilities.

Electrified Highway Drayage

This system relies on electric power typically provided by overhead catenary. The power is provided to a motor in an otherwise conventional highway tractor. The system would require some other vehicle or hybrid capability in order to use legacy marine and rail terminals as well as legacy customer facilities. Wayside power, typically via overhead wire, is in common use for trolley buses and heavy-duty mining trucks. Wayside power requires route-specific infrastructure, either catenary over public roadways or an exclusive road system. Trolley buses and mining trucks typically stay on the system. A closed system might be appropriate for movements between marine terminals and inland rail terminals, but would forego the inherent flexibility and scalability of truck drayage.

Wayside/Battery Trucks

A promising variation not yet tested is wayside/battery power. In such a system, the truck tractor would use wayside power where available for both propulsion and charging the battery and use the battery alone for short trips off the wayside power system. The wayside power/ battery combination is intended to allow the truck free-ranging operation at either end of the line-haul trip. This arrangement would allow electric trucks to intermingle with diesel or natural gas trucks in unmodified marine and rail terminals, and to serve “off-wire” points inland within operating range of catenary power. Such a system would, however, require a way for trucks to move smoothly between wayside power and battery operations. The transition would be more challenging on public roadways.

Conventional truck drayage system capacity is easily varied to accommodate day-to-day volume fluctuations, shifts of volume between terminals, and long-term growth (or, in 2008–2009, short-term decline). Drayage tractors are used in other business segments during periods of low demand and can (within limits) take other routes when freeways are congested. It is far more difficult to adjust the capacity of fixed-guideway systems.

The use of alternative fuels and electric power would reduce the flexibility and scalability of truck drayage systems somewhat. At present, the lack of an extensive fueling network constrains the operating range of alternative fuel tractors. Such tractors can still, however, be used in other local and regional trips:

  • Battery-electric tractors would be useful only for local trips when not in port drayage service.
  • Tractors using wayside electric power for the “line haul” and battery power off the powered guideways would have a restricted range in other uses.
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