Crazy Breakdown Numbers

[jeffryfisher]

Still testing US History...

Just after the turn of the 20th C, I get my 4-6-2 Pacific engines and celebrate. I replace my aging 10-Wheelers and expand all of my passenger/mail trains to 3 cars.

After two years, I begin to notice that my 100 train fleet is suffering 2 or 3 breakdowns every month, which is way too high for 2-year-old engines. This is especially the case in this scenario, where there have been some events allowing me to pay for more train safety (50%, 75% & 10% more safe; and yes, I checked that I had set the effect sliders in the right direction).

Looking at some engines, I see breakdown chances like 8.2% on level ground at 77mph. That's at least double what the older 10-Wheelers had shown before being replaced. Granted, the 10-Wheelers had been pulling only two cars at max 45mph, but they also started with below-average reliability.

Is it possible that some integer inside the program has overflowed, producing whacky effects? If so, is there any way to figure out what it is and how to cap it?

Has anyone ever learned what sort of formula is being used to calculate breakdowns?

[Gwizz]

Break downs come too often in the later years for my taste.

I reduce the break-down using two events, each set at 100% even then I get a few break-downs with locomotives that have low levels of reliability.

I believe break-downs are a random activity, set differently for each locomotive.   

[jeffryfisher]

I've done some poking and prodding to learn the following:

I played a quick few years starting at 1910 in the Heartland scenario (which has exquisitely well crafted terrain BTW). Breakdown chances varied based on several factors:

* Engine reliability rating

* Engine age

* Current speed

* Train weight

* Uphill grade

* Cornering (acts like +2% grade)

* Oil level

Coming out of the chute, a new 4-6-2 Pacific typically displayed a 7% chance of breakdown at 61 mph with high oil on level straight track. With half oil in a turn on a 3.5% grade, the risk soared (it could more than double) even though speed dropped considerably.

So here's what I think happened to me in my US History game:

In 1903, I had been running 10-Wheelers  with 2 pax/mail cars at maybe 40mph. In that era, loaded pax and mail cars weigh 15 tons each, making 30-ton trains.

Jan 1904 gave me my 4-6-2 Pacifics early as the benefit  of an investment event in my scenario (Pacifics normally appear in June 1908). These powerful engines, serving growing cities, run most economically with more cars, so I expanded my consists to 3 pax/mail cars each (45-ton trains). If not for the Rocky mountains and Pacifics' poor climbing ability, I might have stretched to 4 or 5.

Jan 1905 is when the 3rd generation passenger and mail cars appear, replacing 2nd-gen cars as trains turn around. These 3rd-gen cars are 30 tons each loaded. By 1906, my now 2-yr-old Pacifics were pulling 90-ton trains at up to 80mph coming down the plains from Cheyenne and Denver. That was triple the weight at double the speed of just 3 years earlier.

Even in the Colorado river gorge climbing toward Moffatt Tunnel, I found a train churning out 25 mph up a 2.5% grade while entering a corner... and sporting an 8.9% breakdown chance on fresh oil.

Where the track was straight and downhill (not even climbing a green grade), breakdown chances were mostly 3 - 4%, so my safety events seem to have had a beneficial effect. My problems were with engines having imperfect oil, climbing 1-1.5% grades hidden among the green numbers, especially when also cornering.

Turning a corner makes a seemingly harmless 1.5% grade work like 3.5%, nearly red. A train in a zig-zag pair of turns gets hit twice! Now I have extra incentive to space turns further apart and keep trains shorter than the distance between any two curves they're likely to pass, especially uphill.

I have also added oil barns (roundhouses). The manual makes a point of saying that breakdown chances accelerate when oil drops below half. What I had not realized before is that the breakdown chance climbed significantly all the way to the halfway point.

Important safety tip (literally): When you turn that tech corner to powerful engines pulling heavier trains at faster speeds, the breakdown and crash chances far outstrip the slight improvement in reliability rating. In other words, the Pacific's 5 rating is a slightly better starting chance than a 10-Wheeler's 4, but the Pacific is taking on far more danger, especially with pax/mail doubling weight in 1905.

Therefore, add oil barns to all of those "half-way" stations that had only water and/or sand before. Examine old track that you built back when money was tight. Spend more of your millions to reduce/space turns where possible, and smooth bumps in the road. Even work to flatten the 1.5's near turns in the plains.

I also recommend that scenario designers add track-improvement safety events. I like to make my players pay for bonuses, so mine exist as choices offering added quality for a price. Given how gummed-up a main-line can become each time an engine blows a gasket, it's a price worth paying on any large RR.

[Gwizz]

My map is a remake of the heartland map.  This is not the SJ&E RR;  but, the Chicago Hub map I'm working on.

I'm using a lot of Pacific locomotives.  I have had very few breakdowns and no crashes using the pacific locomotive.  But I seldom play past the 3rd year while I test for my faulty status report and I have two 100% reductions events for breakdowns.  On top of that, I use many AI Railroads to deliver my loads running on my track and using my stations.  The AI seems to normally have fewer breakdowns. 

You testing is interesting and beneficial.