Turn Time — Meltdown or Summer Heat Wave?
Truck turn time in Los
Angeles-Long Beach hit another record in October, with 36% of all trips over 2 hours, and a new low of 31 on
the 100-point METRIS Performance Index. In 2010 the time a trucker needed to budget for a trip to meet a
deadline was 2-3 hours. This past July it was 3-4 hours. In October it was 4-4½ hours.
If there's a surprise, it's that the numbers weren't worse. Alarms are going off practically every day
about this and that statistic in the red — like the paragraph above — and the term “meltdown”
has been floated.
TURN TIME RESOURCES
The Journal of Commerce (JOC) lists 12 reasons for current congestion. They're all well
reasoned. That doesn't mean they're all having a measurable impact, or that they all need to be
addressed today. Which of the 12 are most responsible for what's going on now? How are the solutions to
be prioritized? As is often suggested, the answers lie in good data and analysis.
The data indicate that what's happened in the past few months is that the ports have reached their
saturation capacity. A greatly diminished capacity compared with even the recent past. But there have been
no new significant generators of delay for 6 months, and current performance issues are attributable
almost entirely to container volume. Bear in mind that September trade was the 4th highest on record.
This is good news. Because performance degradation under a known stress is predictable
and manageable. When that stress is volume, degradation is also reasonable.
What Does It Mean to Have Reached Saturation Capacity?
Think about a city freeway at 3 a.m., with 2 vehicles per minute in each lane. We're flying along at
65 mph. Double the traffic to 4 per minute, 8/min, even 16/min and there's no drop in speed. There's
capacity to spare. When lane density reaches 30/min, things get touchy. Add more vehicles and speed
slows; take them away and it recovers. So at this point there's a causative relationship
between vehicle volume and traffic speed. The freeway is exhibiting saturation capacity behavior. It
can absorb more traffic, but with a performance penalty.
Now if it were to snow, cars would have to maintain a greater headway distance, and saturation
capacity behavior would begin at 20/min rather than 30/min.
If speed and headway were to decline in the absence of additional traffic, we'd suspect a
complication: an obstruction, perhaps an accident. At 2 vehicles/min the obstruction would not have
caused the same degree of slowing. So there's insidious value in operating near saturation capacity.
Saturation Capacity in Los Angeles-Long Beach
The graph in Figure 1 shows the METRIS Turn Time Performance Index (blue) and container volume
(gray) in San Pedro over the past five years. There's no apparent relationship between the two.
Logically, turn time should worsen (i.e. Performance Index should decrease) when traffic increases. Why
does that not happen? Because times have been good
— like the freeway at 3 a.m. When volume increases, terminals hire more labor
(Figure 2). There are reasons why truck turn time performance has been in a steady decline for years,
but volume isn't one of them.
Figure 1. The mirror image that develops between the two curves starting in
spring 2014 suggests that the ports are currently operating with a diminished capacity of around 1.2 m
TEUs/mo, beyond which volume is directly reflected in poorer truck turn time performance. Prior to 2014
that was not the case because there was copious surplus capacity. Mouseover/click the figure to see the
drop in capacity.
Figure 2. Labor hours per TEU have been steady for years, indicating that
terminals hire more labor during periods of high demand. Labor inputs have not been wanting during
the current performance dip.
Until 2013, swells and dips in monthly volume were routinely absorbed by the system. While the
Performance Index generally declined, it remained in the 45-60 region. Even the 3-year monthly high of
1.34 million TEUs in August 2013 was a non-event in turn time impact. There was still capacity to spare.
The latest data (September container volume, October turn time) have put enough points on the graph
to create a pretty convincing case that the port is in saturation capacity mode. It's been in this mode
since the spring. Volume didn't increase in spring; capacity had plummeted over a period of
time, to 1.2 m TEUs/mo, due to the convergence of chassis issues, mega-vessels … those 12 factors
referenced by JOC. Starting in the spring, any volume over 1.2 got perfectly reflected in turn time.
Unsurprisingly, the 1.4 m TEUs in September, the 4th highest month ever at the ports, caused a
precipitous drop in the performance index.
A second observation from the graph is that capacity may have bottomed out at about 1.2 m TEUs/mo
— the perfect reflection suggests that it has not fallen further in the past several months.
Conclusions and Caveats
analysis and consulting help MTOs, LMCs, BCOs and ports achieve consensus.
Current problems are severe, and the loss of capacity is intolerable. The opening paragraph above
is unambiguous, and the conclusions below take nothing away from that.
But looking at the causes of increased congestion, the constant alarms, and the distraction
they constitute for management, the finding that arises from the analysis is that nothing significant
has just happened, that hadn't happened 6 months ago. The recommendation is to maintain a steady
course: crank up capacity by fixing the strategic issues that were strategic issues 6 months ago (e.g.
chassis), but there's no reason to second-guess directions every week just because of new reports of
falling performance. This is largely about volume. For the record, in statistical terms, volume
accounts for 86% of the April-September variance in turn time (though with just 6 points, that calls
for a pinch of salt). When/if volume falls back to 1.2 m TEUs/mo at the end of this peak season, turn
time and everything else will stabilize. For a month. There is no hidden agenda in this
recommendation; it is based entirely on the data, and it should be read in the context of the
limitations of the analysis.
This is one way of interpreting the data. There are others; the capacity curve could be drawn in
different ways, and more sophisticated analyses are possible, e.g. the impact of dual roadability
inspections can be established quite precisely.
Saturation capacity behavior is recent — six months does not present enough of a history to form
firm conclusions. Nevertheless, the graphic evidence (sudden onset of mirror-effects in the curves)
coupled with basic transportation science, is remarkable and persuasive. This analysis is based on
observations on truck turn time only, not container dwell time (ship-to-exit-gate) which has also
fallen out of control, but is probably a domino effect.
An unmistakable takeaway is that there are data that can illuminate what's going on, and
analysis is key to understanding and remedying the congestion problem.
Epilogue — Something Grim Happened in October
The article above was posted on November 12, based on container volumes to September, and turn
time to October. On November 17, the ports released October traffic statistics.
The figures were low. The reasons are fairly obvious: the season is tapering down; vessels are
anchored offshore instead of discharging cargo; and with San Pedro choking, other ports are beckoning
But that’s not all of the bad news.
In Figure 1 above, the pattern of reflection was perfect, assuring. Although October turn time
performance was at a record low, it was a continuation of a 6-month pattern, reasonably suggesting
a strain against volume. The figures below, which incorporate October volumes, tell a troubling
Figure 3. The same graphs as in Figures 1 and 2, with October volumes included. Left: Despite relief on container traffic,
performance sank further. Right: Symmetry emerged in labor hours vs turn time. For the past two
years, the pain of MTOs and LMCs has been in a near-perfect pas de deux.
The bad news in Figure 3 is that the October numbers blew the symmetry we saw in Figure 1. We can
not take comfort in the notion that the performance dip in October was all about traffic, as it was
in April-September. Performance plunging to a new low, despite a volume decrease, is a sure sign
that something else was going very wrong. The METRIS index was 10 points below what we'd expect for
that volume. Ten points are 1½-2 times the gross impact of the 2012 strike (the strike lasted 8
calendar days; the effects here are over a 30-day period, so the impact is less than that of the
strike on a per-day basis, but still substantial). The pain was intense for both terminals and
I humbly withdraw the contention that nothing new has happened in 6 months. That was true as far
as September. Something new did break down in October, and it's important to get to the bottom of it,
identify and measure its components, and address them. Identifying the components is not my specialty.
Based on the data and reputable news sources, I'd guess at one or both of:
- An entirely new source of delay. Labor problems come to mind, particularly the reported
secondary roadability inspections and equipment staffing. Fortunately it is possible to
quantify some of this delay. It is also possible to address it relatively quickly, at least in
theory, with the right will and human factors.
- An existing source of delay either echoing (e.g. backlog), or spiraling out of control due to
domino effects. Examples: (a) As turn time worsens, containers don’t get picked up on time, they
remain on the dock, increasing stack occupancy, which slows turn time further. (b) Containers
arriving off-schedule at BCOs take longer to process, delaying backhaul of empties. (c) Deadhead
trips (bobtails, bare chassis and empties) increase. (d) Chassis shortages lead to hoarding by BCOs
and MTOs, compounding that problem. These are difficult to isolate and measure, and it will take
more than will to fix them. They require an extraordinary application of corrective force, at some
cost, to arrest the spiral.
At least three commendable fixes are under way. Terminals are flexing breaks, and the effects are
noticeable particularly on 10 pm queues. A chassis agreement promises to
ease the chassis problem after February 1. An off-dock empty storage dump will relieve terminal congestion.
A respite from record traffic is on the horizon, at least for a few weeks.
Will these suffice?
“U.S. Container Port Congestion & Related International Supply Chain Issues: Causes, Consequences & Challenges.”
Federal Maritime Commission, Bureau of Trade Analysis, 2015 07 14
The statement on page 54, attributed to a METRIS report: “[evening queues are] not being addressed because
the marine terminals that operate the PierPASS program do not consider the long lines outside the gates as
their problem....” is not taken from DGRC's works.
“Near-record volume is main driver of LA-LB congestion, study finds.”
Journal of Commerce, 2014 11 14
“LA-Long Beach congestion swells on longer container dwell times.”
Journal of Commerce, 2014 11 24
“Increasing container dwell times are taking a toll.”
“LA-LB truck turn times worst ever, but long box dwell time worst of all.”
Shanghai Shipping Exchange, 2014 11 28
Turkey Sea News, 2014 11 28
“Chicago drayage operators worried port congestion could hurt their business.”
The METRIS data archive, on which this article is based, was possible due to the cooperation and
patronage of leading drayage carriers who have been our partners over the past 7 years:
Ability/Tri-Modal, California Intermodal Associates, Dependable Highway Express, Fox Transportation,
G&D Transportation, Golden State Express, Harbor Division Inc, LA Grain, Port Logistics Group, Price
Transfer, Progressive Transportation Services, Southern Counties Express, TK Transport, TTSI and Yamko
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