Blocking Symbols

 This whole thing is a confused mess. I’m getting a lot of information about the La Mesa* MRC’s blocking symbols and how prototypical they are. Yet every effort to determine if these symbols are in fact the way things were done is leading me in another direction.

La Mesa has a list of blocking symbols too long to list here. Their large Bakersfield yard builds blocks of cars based on these symbols. 

The premise is that the SP-ATSF blocked cars by commodity, then when enough cars were gathered (Either from one block, or by combining several blocks) these were assigned to a train. 

At La Mesa there are three basic eastbound trains, #802, #804 and #806. Each of these trains covered the needs of the railroad within a particular block of time, over a specific Route. 

So, for example, 802 took all freight between 8:00am and noon; 804 took all freight between noon and 4pm and 806 took all freight between 4 and 8 pm from Bakersfield to Los Angeles.

Each train was further sub-divided by the running of sections. So if train 802 was limited to 60 cars but Bakersfield yard had 180 cars of freight to move between 8 am and Noon, then 802 ran in three sections.

If Bakersfield Yard had a block of perishable produce,  the YM in discussion with the DS might determine that this block should run in train 1-802, while sending the blocks of building materials in a following section.

Now this system might actually have been the prototypical template for how the SP ran traffic over this route, IE Bakersfield to Los Angeles. Keep in mind the La Mesa Club models only (and to say, in this case “only” is a gross understatement) Bakersfield to Mojave. At Mojave ATSF traffic splits off and heads to Barstow, while SP traffic continues south to Los Angeles (Remember, also, that the Palmdale Cutoff won’t be built until 1967).

My point here is the SP-ATSF when looked at in their entirety blocked cars by destination. La Mesa blocks by commodity and operates the line more as a conveyor than a railroad. Once La Mesa gets all the produce cars over their line, this produce moves east in trains carrying blocks of this produce to city destinations. But this all takes place “Off-Layout”.

WELL ANYWAY, because I was seeing ONLY LA MESA procedures I was proceeding on the assumption that Western Roads blocked by commodity, and I wanted to see if Eastern Roads did it differently. I found out that Eastern Roads in fact did it the same as Western Roads, its La Mesa that does it differently.

As it turns out all railroads block by destination. They call these blocks by different names. Each block is assigned a symbol which may be all letters, others alpha-numeric, some just names. Some railroads simply put everything for Pittsburgh in one train, no matter what. Others do, in fact, group a commodity into a block.

But it’s a block of a commodity going to a particular destination.

If you are modeling a big yard you might be able to build a large block of all auto-parts going to Atlanta. Then the “Atlanta Auto Parts” block might get assigned a symbol, like “AAP”.

But as a general rule you wouldn’t build an AAP block and after a short discussion with the DS, decide to run the AAP block in or as Train 94, because 94 goes to Memphis. Everyone knows 98 goes to Atlanta. 

*I should state that I am persona non grata at La Mesa and I have a self-imposed life time ban from attending op sessions there. Over the years the problems I had at La Mesa have aged out. They left the club a long time ago. I, however, still hold a grudge.