Proyectado Patio Coyotepec
Thanks to
information provided by Mexlister Michael Krumholz, I have obtained a copy of “Transportation
Research Record” No. 927, from [
Coyotepec Yard was planned by NdeM
to handle 6000 cars per day in 70 trains,”[to be] the largest in the
The following
points were considered in the design process:
1. Yard layout
2. Yard data
systems
3. Process control
systems (PCS) [the humping control]
4. Trim-end design
5. One-spot system
[freight car light repairs] and engine facilities
6. Operating
philosophy
7. Operating
management control points
8. Key operating
buildings
9. Communication
and signals (intrayard communication, interlocking
design, and control of yard movements)
10. Television
monitoring system
Planning the yard
layout was influenced by three major factors: the boundaries of the available
real estate, the desire to construct the project in phases, and “the
preconceived notion of yard design imposed by the previous operating experience
of National Railroads of México personnel.” (Some of these preconceptions were
abandoned with more experience.) Two basic designs were considered: “an in-line
yard in which cars are pulled from the classification yard to the departure
yard and a shove-back yard in which cars are pulled from the classification
yard and then shoved into a parallel departure yard.” Seven possible layouts
resulted, and “the one selected was a compromise that had both in-line and
shove-back departure yards operating through a single multi-track pulling
throat that will be able to work five engines at the same time under ideal
conditions.”
To aid the
planning, computer simulations were performed, and the resulting experience was
later helpful in designing another new yard at
The final layout of
Coyotepec Yard, approved by SCT, contained:
1. Receiving Yard
2. Hump with
capacity of 6 cars per minute, and weigh-in-motion
scale
3. Classification
yard with 64 tracks in 8 groups of 8 tracks (the first 8-trackgroup will
receive cars for TVM yard only), a master retarder, 8
group retarders, and another group retarder for 6 tracks to the One-spot (each of the64 tracks
on the bowl will have tangent-point retarders and
inert retarders at each end); coupling speed will be
controlled at 4 mph by a double radar measuring device;
4. Two trim-end
designs, one with a single key and one with three keys [this refers to one
versus three parallel tracks to pull down from the distant end of the classification
yard into the departure yard. Obviously, having more “keys” widens the
bottleneck, though has other drawbacks]
5. One on-line
departure yard
6. One parallel
departure yard
7. One transit
train yard (relay yard)
8. One minihump with five tracks of 35 cars each
9. One transfer
yard
10. Two support
yards
Also, there was the
One-spot car repair, two separate engine terminals (for electric and diesel
locomotives), and 43 different types of buildings including a hospital and “fire
center” [bomberos?]
State-of-the-art
computer systems for all yard functions, were planned
as a matter of course. Likewise, internal communication methods were also
planned to be state-of-the-art. The car management system proposals were
modeled after those developed by the Missouri Pacific and Southern Pacific
railroads in USA.(The article goes to considerable
detail on the plans for automating the functions.)
The mechanical
services are described: “The car repair facility will have the capacity for 61
light repairs and 120 on the one spot (four tracks). It will also be able to
wash and supply 100 cabooses, to repair 5 cabooses, to wash 20tanks [I assume
this means tank cars for potable water], and to transfer freight loads between
two tracks. The facilities for electric engines will have the capacity to
handle washing, travel inspection, and sanding of 121 engines. For diesel-electric
engines the facility will have the capacity to handle washing, fueling, and
light repair of 181 engines (capacity, 12 per day).”
An “extensive document”
was prepared in early 1982 to define the plan of operating the yard and its
interactions with the main lines that pass beside the site. Through this
document, it was hoped to anticipate potential problems and find ways to
mitigate them. (Presumably it would have formed the basis for an operations and
training manual had the project ever come to pass.) The entire planning
process, it is said, consumed at least eight months during 1981-82,with expectation of opening the yard for operations in
1985.
To connect both
ends of the yard with the main tracks, locally controlled interlockings
were decided upon, offering more flexibility than remotely-controlled CTC, in
which Coyotepec would be only a small part of a dispatcher's
territory. Many switches and signals within the yard were to be controlled
directly from the hump tower or trim tower, to increase efficiency. A
television monitoring system was proposed to observe the car numbers of arriving
and departing trains.
The recommended
yard design was to have “an in-line receiving yard, a classification yard with
64 tracks, an in-line departure yard for trains departing to the south, and a
parallel (pullback) departure yard for trains departing to the north.” The
receiving yard was planned to have 14 tracks initially, growing over time to a
maximum of 22. Each of the departure yards was
similarly planned to start with 7 tracks eventually expanding to 12.
The concept of one
versus three connections (keys) between the classification and departure yards
is discussed at length, noting that subdividing the departure yard limits the
flexibility of track assignments in the classification bowl and makes it more
difficult to respond to day-to-day situational changes. It also observes that
the three-key design had 30 percent more switches, noticeably increasing
infrastructure expenses.
Trains to
Staffing: the plan
details the anticipated crew needs under increasing levels of traffic during
the years 1985 to 2000, starting with (on each of three shifts):24 inbound car
inspectors, two hump engines with five people per crew, five trim-engine crews
each of five people, nine outbound car inspectors. This would increase to 42
inbound car inspectors, three hump engine crews, eight trim-engine crews, and
15 outbound car inspectors, also on each of three shifts. It is suggested that
the yard be operated with minimum crew levels that can be augmented when
traffic growth demands, rather than beginning with too much staffing that would
be unpopular to reduce.
The TRB article
offers two schematic diagrams that demonstrate the one-key and three-key
designs, but gives no detailed illustrations or any that are
specific
to the actual plans for the proposed Coyotepec yard. It was apparently planned to build the yard
on the east side of the main lines, here being (west to east) Lineas A-Juarez-Morelos-B. The length of the yard isn't
stated but my estimate is about five kilometers
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The municipal
center of Coyotepec (Estado de México) is located
about 1.7 km west of FNM's main line north from
The most obvious
question is, why was the Coyotepec
Yard project suspended unbuilt, never to be
considered again? Probably, changes in technology, traffic patterns and traffic
levels reduced the demand on Terminal Valle de México to a point that the
existing facilities could accommodate. México's (and NdeM's)
periodic fiscal crises almost certainly contributed. There may have been local opposition
to constructing a large railyard at that location, or
perhaps it was decided to be too distant from the city. The complete answer
isn't here.
R. Todd Minsk /
March 2002