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Methods of
HO Operation
at SDMRRA


     1. The member-in-charge is the final authority for operations. The following variants are recognized operations styles:

     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 trolley-configured blocks.

     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 occurs.

DCC Operations:

DCC operations on the SDMRRA HO layout may be quite different from other layout operation. The HO layout is 15 scale miles end-to-end; that is a 30 mile round trip. At 30 MPH, a train takes an hour to traverse the layout, assuming there is no oncoming traffic at single track sections. In reality, it is more like two hours for a complete trip from San Diego to El Centro and back.

On a good day with no major layout or equipment problems, a DCC crew can engineer three unit trains per operator in a 6-hour day. If there are switching operations taking place, or if the layout is very congested, it can be only two trains per operator per day.

Like most major users of DCC, our Association has occasional DCC issues. A current investigation involves number of locomotives, whether or not sound equipped, and other factors such as lighted passenger cars, etc. A worksheet (click here to view) has been prepared to allow crew leaders to record particulars of an operation which might shed light on layout problem areas or DCC command station malfunctions.

Some items sure to cause problems under DCC are:

  1. Duplicate cab addresses in simultaneous use.
  2. Unintentional duplicate locomotive addresses.
  3. Short circuits on the layout
  4. Incorrectly creating consists, or killing another operators consists
Accurate record keeping of locomotive addresses and checking between crew members for conflicts is a lot of work but it pays off during operations. As far as cab address conflicts, the Association keeps a posted list of first-come-first-assigned cab addresses (click here to view).

Short circuits are another issue. Other than occasional derailments, most short circuit issues fall into two catagories:

  1. Incorrect wheel guage, especially on locomotives.
  2. Incorrect track geometry, most often at turnouts. Long wheelbase locomotives are the first to identify geometry faults.
Allowing a short circuit to persist (operator inattention) or confusion which equipment is producing the short will cause the DCC command station, boosters, or power shields to attempt reset over and over. Locomotives have been observed to scramble the decoder programming and suddenly generate a "Factory Reset". If the locomotive reset is part of a consist, it is difficult to recover from this problem. Long-term shorts may also permanently damage a locomotive decoder.

Analog DC Operations:

Analog DC operations on the SDMRRA HO layout is confusing to operators who are used to DCC operations and methods. There are at least 3 DC throttles and sometimes four for each district (panel) on the layout. Operators must divide up the panel between eastbound and westbound controls, usually RED throttle for eastbound and BLUE throttle for westbound, but it is up to the operator which throttle to use for which purpose. Throttle direction is important especially at panel natural boundaries, and good communications between operators is essential.

Depending on the number of operators, panel operation is usually the choice for analog DC. Usually panels such as Campo and Dos Cabezas are set to override to neighboring manned panels, and Union Station/Rose Canyon is a combination of override and remote throttle. Again, each operator has his own perferred method.

The branch line is seldom operated analog DC except for trolley & traction freight. Trolley has the advantage of not being sensitive to throttle direction except to control initial forward direction of the trolley. Once set, it need never be changed, and the trolley will travel from loop to loop and back again. The only issue is where the trolley must cross the main line on Market St. The trolley operator (often the same operator as the San Diego Freight Yard) must determine when it is safe to release the trolley on the crossing.

Unlike DCC, analog DC operators must match voltage (and direction) when transitioning from one district to another. Volt meters and Amp meters are installed on every panel for each throttle, important because there is often a large variance between locomotives with respect to how much voltage is required for a given train speed. Current (amps) may allow the operator to tell when a train is entering a throttle, leaving a throttle, or if a short circuit exists (often a switch is against a locomotive). It is very important on DC to pay attention to voltage and amps for each train, especially if it is out of direct view.


     This page last updated: April 2013