Command control is an essential element of the Operations Road Show layout.
Jack Ozanich put it succinctly when he said "I'd sooner give up Kadee
couplers than give up command control." We're largely in agreement with
Jack-- we cannot conceive of trying to run timetable and train order operations
while having to mess around with toggle or rotary switches to assign power
blocks. It would be just too distracting.
Digital command control was the obvious choice for our layout, given its
availability, its relatively low cost, and its inherent ability to support
functions other than simply controlling train speed and direction. We put
this extra capability to good use on the Operations Road Show layout, because
in addition to controlling the speed and direction of the trains, we wanted
to use it to:
- Control the signals for the train order system
- Control the six fast clocks (later increased to eight) installed
around the layout, permitting us to synchronize them as well as start
and stop them simultaneously
- Control the alerter buzzers for the phone system
That last application was a last-minute solution to solve a problem we hadn't
considered in the design of the phone system. We think that it shows the flexibility
of digital command control quite nicely.
One other requirement we had for the system was the availability of radio
throttles. We felt these were necessary to provide the type of user experience
we wanted our guests to have- we felt that hunting for plug-in panels was
part of the experience that our guests could do without.
Although we'd been using Digitrax equipment for a few years prior to building
this layout, we took a "clean slate" approach and looked at all of the major DCC brands available in the US
at that time (Digitrax, EasyDCC, Lenz and NCE) in order to be sure that we
would select the right system for our purposes. We chose to use Digitrax
DCC products for this project due to the availability and robustness of Digitrax's
radio throttles, the availability of LogicRail
Technologies' LocoNet Fast Clock, and the ready availability of Digitrax supplies
from a local dealer (then Michigan Model Train Center) and several other dealers
not more than 60 minutes' drive away. Digitrax also had the best selection
of accessory decoders to choose from for automating our train order signals.
- The core of our Digitrax installation is a Digitrax Chief system which
- Six power boosters
- Two PM4 power management cards, controlling several power districts
in the Fiddle Yard and Lafayette Junction/East Yard area, as well
as the reversing section needed by the NYC/Monon/NKP interchange arrangement.
- Eight LocoNet Fast Clocks, two of which are wall-mounted at the
layout's home base.
- Three DS54 I/O cards to interface with the dispatcher's train order
signal controls. For technical details of our train order signal system,
see Building the DCC-Controlled
Train Order Signal System, elsewhere on this site.
- Two Team Digital SIC24 Signal controllers to control the signals at the interlockings with the Pennsy at Logansport and Clymers.
- Ten DS44 accessory decoders to control the train order signals,
the indicator lights in the signal control panel, and the phone alerter
- Two UR91 (simplex) and three UR92 (duplex) radio receivers. The second
simplex receiver is not required for a layout this size, but provides
a reserve for use as an emergency backup.
- 38 UP3 and UP5 throttle jack panels installed around the layout
in case we need to set up the layout in an environment that is completely
inhospitable to radio operation. They also serve as battery savers
for the throttles during sessions.
- A laptop computer running JMRI software, interfaced to the layout using either a Digitrax PR3 interface, or an RR-CirKits LocoBuffer USB. We use the JMRI Loconet Slot Monitor feature to quickly break down motive power consists on trains terminating in the Fiddle Yard.
In late 2017, we purchased a DB210 booster, which we evaluated to determine whether it provided sufficient benefits to justify retiring and replacing our older DB150 and DB100 boosters. Our assessment is that it is superior to our existing boosters, so we have replaced our DB150s and DB100s with DB210s. The key benefit that sold us on the DB210 is that it functions in such a way that we do not have to be fussy about the order in which we bring up the command station and boosters when powering up the layout.
Since we are asking convention attendees to devote three hours of their week to our operating session, we have deliberately designed our DCC installation very conservatively and with redundancy. A lot of what we do would be overkill for most home layouts and reflects the reality of having a traveling layout that must perform well in a variety of external conditions that we are unable to control.
Even with all of the DS44 and DS54 accessory decoders, we do not use the
command control system to throw turnouts- all turnouts are thrown by hand,
using a variation of the old choke cable system.
We use up to 15 throttles during a session, from a pool that includes a DT500, several DT400s, DT402 and DT402Ds, a dozen UT4Rs, an increasing number of UT4Ds, and a couple of DT300Rs
we keep in reserve. A single UR91 receiver at Lafayette Junction and UR92 transceivers
located near the Fiddle Yard, New Waverly and Rockfield afford excellent coverage across the entire
layout area, and handle the throttle traffic quite well.
We send out crews with Digitrax's UT4R or UT4D utility throttle as thaey are easy-to-use throttles with familiar
Nearly all of the RJ12 cables we use to carry LocoNet signals around the
layout were custom-made using flat wire and connectors bought in bulk. In the past, we tried to use six-conductor phone extension cables purchased
from a local hardware store, but we found that we couldn't rely on the cables
working due to poorly-crimped connectors on an unacceptably high percentage
of them. We are great believers in using a cable continuity testing box to
test every cable before connecting it in place during setup. Doing that has saved us many
hours that we would have likely spent diagnosing problems caused by defective
or damaged cables.
Layout Design Considerations
Although we decided from the outset to design the layout to operate exclusively
under DCC, the only thing that we did differently on this layout as a result
of our DCC focus was to use 12-gauge stranded wire for the track bus wiring.
This minimizes current and signal loss along the lengthy runs of wiring. To
ensure continuity through the rails, every segment of rail on the layout has
a feeder soldered to it. We do not rely on rail joiners to carry power between
sections of track. Even the bridge tracks we use between modules have power feed drops.
Despite planning to use radio throttles, we installed 38 of Digitrax's
UP3 and UP5 panels in the fascia. The main reason for this was to ensure
that we could operate the layout if for some reason our ability to use
the radio throttles were impaired. This is in recognition of the fact
that radio interference from outside sources is a variable we are unable
to control when the layout is being used at a convention. We experienced this briefly during one of our sessions at the Cleveland Convention, when an outside contractor was installing and tuning cell phone repeaters in the Convention Center.
Taking a "belt and suspenders" approach to ensuring that
we can continue to operate in the event of failure of a radio system component,
we have a second UR91 radio receiver in the Delphi/Clymers corner
of the layout. This provides an installed spare that we can bring up quickly if anything
should happen to the "main" UR91 located at Lafayette Junction.
Plus we carry another spare.
Since the layout is designed to be set up in only one configuration, we chose
not to install the LocoNet cable permanently into each module, with the attendant
connectors and jumper between them, but instead to custom-build cables for
the specific runs between UP-panels. We tagged and numbered each cable so that we
could identify its intended use. We do not feel that this particularly increases
our setup time as compared to connecting short telco cable jumpers between
each and every module. It also reduces the number of cable segments and the
number of connectors needed in the system, which increases reliability.
To date, the only hardware failures we have experienced with our Digitrax
installation were from a batch of defective DS44 accessory decoders
we used to control the train order signals. We found that we had to
continually re-program them, as they would lose their memory whenever
a short-circuit occurred during testing. Once they were replaced with new ones,
we had no further problems.
Intially, we wired the train order signals to take their command
signals from the rails on the module. The disadvantage to this, we discovered, is that it is possible for signal commands
to be missed if a short circuit on the track has shut down a power district a signal is connected to. This is similar to a situation other modelers have encountered
when controlling turnouts using accessory decoders. Our solution to this was
to run a second two-wire DCC track signal bus solely for the train order signals
and phone buzzers beneath the layout. While we chose to dedicate a booster
to controlling this bus, we could have chosen to feed it from one output of
a power manager board connected to one of the other boosters.
The radio system reliability has been excellent, and we have no complaints.
We have experienced persistent reception difficulties
due to site environment issues twice. The first was at the NMRA National Convention
In Cincinnati, when a neighboring layout's radio throttles were interfering with ours. Bringing the second UR91 on line solved the problem
quickly. The second was the previously-mentioned period at the 2014 Convention in Cleveland, while the Convention Center was, as we later learned, installing and tuning cell phone repeaters during one of our sessions.
have discovered, as have other users of virtually all radio throttle
systems, that having the receivers mounted above head height improves
radio reception by drastically reducing signal loss due to bodies being
between the receiver and a throttle. This was driven home to us during
a session in Saline when we had far more guests than we had jobs. At
one point, six people were viewing the layout from the aisle adjacent
to our UR91 radio receiver, which at that time was mounted in the fascia.
While they were standing in front of the receiver, we had considerable
difficulty controlling our locomotives. Once the crowd moved on,
the system resumed operating as reliably as we are accustomed. We were
able to duplicate this under controlled circumstances at a work session
later that week, and so moved both the primary and back-up UR91 receivers
up onto poles so that they are approximately seven feet above the floor
during operating sessions. We have not had any reception problems since.
At the Hartford National 2009 NMRA Convention, we began using Digitrax's then-new duplex radio system. Having acquired one of
the first UR92s and DT402D throttles sold to the public, we used the
duplex throttle primarily in the Fiddle Yard to reduce cable-tangle
when two of us were making up and breaking down consists. Even with
the early-release firmware, this worked very well for us.
Since the Hartford convention, the UT4D duplex throttle has been released
and we have been using it as a road throttle. In doing
so, we have discovered that the UR92 receiver benefits just as much
from being raised to a position above head height as the UR91. The way
we operate, however, we did not see any significant advantage to having
crews use a duplex throttle on trains out on the layout, so we decided not
to convert our existing UT4Rs to duplex throttles. We do not anticipate that Digitrax's having discontinued production of the UR91 simplex receiver at the beginning of October, 2014 will have any effect on us for some time, as we have ample back-up hardware available should either of our UR91s fail.
Most of our locomotives are outfitted with headlights, Gyralights and
a red warning light. The headlight is controlled by the F0 key, as on
most locomotives. The F1 key turns the Gyralight on and off,
and the F4 key dims the headlight.
four LocoNet Fast Clocks we have mounted facing inward at the corners
of the layout are visible across the length of the layout. We also have
one at the Dispatcher's desk and one in the Fiddle Yard. The only thing
more we could wish for would be that they were available in an analog
design more fitting the era we're modeling, which dates to a good seven
years before digital clocks began to emerge. Since all of the LocoNet
Fast Clocks can be controlled from any clock unit around the layout,
or from a DT400, DT402 or DT500 throttle, it is very easy to adjust the time
or clock speed.
During the summer of 2007, we added another LocoNet Fast Clock to the
system in the form of a wall-mounted clock in the crew break room in
the basement in Saline, so that off-duty crews can watch for their call
times. Based on feedback from guests at the Great Lakes Express 2007
operating sessions and clinics, we have also added another, large, LocoNet Fast
Clock high up on one of the layout room walls, to make it easier for crew members
under 5'4" tall to be able to see at least one fast clock from
anywhere on the layout.
In mid-2010, we acquired ten Maha PowerEx NiMH rechargeable 9.6 Volt batteries and a ten-slot "smart charger". This combination has served us very well. The 9.6 Volt batteries hold enough power to get us through a full nine-hour day of operation at a Convention, and our less-demanding five-hour sessions at our home base.
We keep the batteries in the smart charger between sessions, so they're always ready to go. Using them this way, we have found them to have a useful life of about four years before they start shorting out and will no longer hold a charge.
Based on recommendations from other Digitrax users, we ordered several Maha Imedion 9.6V batteries to experiment with. They arrived after we returned from Highball to Indy 2016. We have tested them and found that they hold a charge much longer between sessions than the Powerex batteries, without being left on the charger.
We've been extremely happy with our DCC installation, and the Digitrax equipment
in particular. Using DCC simplified the wiring to the extent that it was even
possible to complete the construction of the layout in time for the
NMRA Convention in Toronto. It also relieves us of having to provide training
for power-routing block controls on the layout itself and spares our guests
the distraction of dealing with power-routing issues while getting their minds
around our implementation of timetable and train order operation.