General HO Standards
1. The primary scale of the Carriso Gorge Exhibit shall be
3.5 mm equals 1 foot, known as HO scale.
B. Prototype Portions Modeled
1. The San Diego Model Railroad Association's HO exhibit is based
on the San Diego and Arizona Eastern Railway from San Diego Union Station Eastward
to El Centro, California. In addition, the branch line from San Diego to Foster is
also modeled. The SD&AE Coronado branch will not be modeled.
2. A portion of the AT&SF Railway from National City,
California Northward to Rose Canyon and beyond is also modeled. This portion
includes the AT&SF freight yard, the freight spurs and common trackage at
Union Station, and the hidden North Loop.
3. The 3 ft narrow gauge leaving Plaster City is based
on the prototype U.S. Gypsum Corporation Narrow Gauge Railway.
C. Functional Concept
1. The layout is constructed as
separate portions, each of which may be operated independently.
- The AT&SF portion from Rose Canyon to National City and
the Mexican border. This division is double track mainline and
contains large reverse loops at both ends capable of turning
trains of unlimited length. This may be operated as a dogbone
for continuous running.
- The SD&AE portion (known as the Tijuana & Tecate while
within Mexico) begins at the reverse loop just outside Tijuana,
recrosses into the United States and ends at the balloon track at
El Centro. The Carriso division and El Centro division are single
track mainline with periodic passing sidings. Siding minimum
length allows 35 cars (40 ft) plus 2 road locomotives.
- The East branch from Foster/Santee through the downtown area
and South to the International border at San Ysidro. The branch
equipped with overhead wire on the majority of track for trolley
operations, but supports simultaneous operations by steam or diesel
2-rail equipment. The branch line is also single track with siding
length limited to about 6 cars.
2. Conventional DC throttles are used on
all portions of the layout. The branch line and narrow gauge use
Innovator commercial throttles with automatic short circuit crowbar
protection, while the remainder of the railroad uses member-constructed
heavy-duty throttles which are protected by external circuit breakers
for short circuit protection.
3. A DCC system is also installed on the HO layout. A Command Station
manufactured by NCE controls the entire layout. 10 amp boosters are installed
at every panel, and Tony's quad power shields provided power via block toggles
to the track. Blocks can be shut off for short circuit isolation, and selection
of toggles further isolates groups of tracks. Conventional DC throttles are
isolated via a member built relay panel during DCC operations. At the current
time, wireless cabs are not used on the HO layout due to interference with
adjacent layouts in the Museum.
4. A separate NCE Command Station is used for programming decoders on a dedicated
programming track. Use of a separate Command Station prevents inadvertant interaction
with other locomotives on the layout. The programming Command Station is also
available as a spare should the main Command Station fail during an operating
1. The goal of the Association is to construct a museum-quality
exhibit. Integral to this is the requirement for accurate models of existing or
historical prototypical structures of San Diego and Imperial Counties. Structures
include railroad related buildings, bridges and trestles, recognizable
commercial buildings, and free-lance buildings which capture the flavor
of an area but where existing buildings may not be used due to space limitations.
2. Where possible, historical structures will be
constructed from original plans. If such plans are not readily available,
photographs may be used. In some cases, a visit to the structure for measurements
may be possible. Free-lance structures may be constructed by combining photographs
of two or more existing buildings.
3. Commercial kits may be used for generic structures
such as tilt-up warehouses, residential houses, or may be used as parts for
E. Equipment on Layout
1. All equipment running on and scenery attached
to the layout shall be HO scale. The large vista areas do not require the
use of forced perspective. Painted backdrops shall not cause equipment to
appear out of scale.
2. British OO scale equipment (4.0 mm equals 1 foot)
may be operated on the club layout provided it meets clearance requirements
and has been granted a variance by the member-in-charge. OO equipment is by
definition non-standard, and is exempt from NMRA Standards and Recommended
Practices, although non-RP-25 wheel flanges are likely to cause problems.
Foreign prototype equipment may be equipped with other than Kadee-compatible
knuckle couplers (link and pin for example), but operation must be reliable.
3. Non-standard is defined as cars, locomotives
and streetcars that do not meet club Standards. Non-standard equipment
may only be operated with a variance granted from the member-in-charge.
A variance is valid only on the day issued. Permanent variances may be
issued by the General Manager, or the chief carknocker. Owners of equipment
failing to meet NMRA specifications must remove equipment from the layout
in the event operational problems are encountered. A variance is voided
when equipment is removed and may not be returned to the layout without
4. When equipment is damaged, the member causing
the damage is to notify the owner and the member-in-charge. The owner may
choose either repairs or replacement and the member causing the damage is
to honor the request. When a guest damages equipment, the host member is
responsible. Damage to scenery is to be reported to the member-in-charge.
After damage to any portion of the layout, a bad order slip must also
be completed and dropped in the Association layout mailbox. Damage which
affects normal operation should also be listed on the whiteboard to alert
1. The member-in-charge is the final authority
for operations. The following variants are recognized operations styles:
- Panel with unit trains, point-to-point, no switching requirements
- Panel with unit trains, "Christmas Tree"
- Fast Clock Timetable (unit trains)
- Fast Clock Timetable with switching
- Engineer (follow own unit train over entire layout)
- Engineer with switching (computer generated waybills)
Note: Panel operation does not work well with DCC.
Branch line operations may follow any of the above variants. In addition,
trolley operation has priority on the branch line. Other equipment must
interleave with trolley operations and use care to not overrun gaps into
2. The Vice President/General Manager when present
may overrule the member-in-charge in all matters related to operations.
3. Members of visiting clubs must abide by the
same rules, regulations, and standards as members of the San Diego Model
Railroad Association. A visiting club must designate one of their members
present as their representative in case damage to the layout or equipment
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