Short

Shortest?

Not quite sure what you’re after here prof, but a 1 car long between the clearance points using Y turnouts would probably be the shortest you could do.  Y’s for the shortest geometry, 1 car because you can run around one at a time to get to the other end of any number of cars.

Not very prototypical of course, but that didn’t seem to be part of the question.

32 Inches

These are all about 7" long adding an inch for couplers at both ends and a little clearance gives us 16" for the boxcars.  Put an 8" turntable at each end of 2 tracks for the locomotive adds another 16" for a total of 32". 

I don't have these models myself, so these figures may need to slightly adjusted based on the models lengths over the couplers.

Paul

 "What is the shortest

Pretty easy to figure out. Just set your engine and cars on a table top and measure them , then measure the clearing points for the turnouts you prefer and add up the total.  BTW, I'm thinking of adding a short runaround track to my yard as I get tired watching the engine run all the way down the yard and back to get on the other end of a caboose :> )....DaveB

Two possible configurations

Using the following information;

50’ boxcar - Currently active equipment

Truck Centers: 40’ 10” ( + 6’ 8 1/4” to car strikers) = 54’ 2.5”
Over End Sills: 50’ 6 5/8”
Extreme Width: 10’ 8”
Length over pulling face of couplers normal: 58’ 6 1/2”

GP40

Truck Centers - 34’ ( + 10’ 6” to car end from truck center) = 55’
Extreme width 10’ 3”
Length over pulling face of couplers normal: 59’ 2”

Minimum radius 26" based on the peco #5

First test point to point length : 188' (approx.) Loco(blue)

Second test: point to point length: straight section 202' (approx.) other 213' (approx.)

And one more(wye) Track length point to point 158' (approx.) (15' centers)

or based on the requirements use 4 turnouts (can be minimized with two speciality turnouts (based on wye))

Didn't the "Timesaver" have

Didn't the "Timesaver" have about the shortest run around possible for the equipment that ran on it? 40 footers?

Two shortest Prototype runarounds I have seen

The two shortest runarounds I have seen/used both held 3 cars. 

One was at a facility that received various steel cars and had a bunch of odd track arrangements that we could not take our locomotive on. We also were not really supposed to use it as a runaround, but sometimes it was the only way to get a around cars.

The other facility with a 3 car runaround was a chemical plant that had two of the spots on the runaround  with enough room on either side to clear additional cars and power. What was interesting is they may only release one or the other car. That means you could not touch the car in the one spot, but still had to pull the empty and replace with another load. You also may have to take the same care from one spot in the plant and spot it at a different location. There was another crossover just up the track that was often used as a runaround to get around these cars. Pretty straight forward track arrangement could take crews hours sorting, spotting, and re-spotting cars. 

Not an answer to the question

Hi,

for a prototype in a long gone era, I would assume that a simple turnout with enough track could be used for a run-around maneuver. Either as a "flying switch" or using poles/chains to get a car or two in or out of the spur.

For a model that won't work, though. I do agree that running around a single car will do the trick. It is much slower, though.

At this point I wanted to link to an entry from Carl Arendts' Small layout design contest - however it seems the page is currently offline :-(

Have fun!

Single stub end track

Single stub end track constructed on a 1.5 % grade ,long enough for the locomotive . Set the brakes on the cars ,uncouple and back onto the stub ...throw the switch,  release brakes on cars.

Very shortest?

Since we are talking model trains here the shortest would be zero, just pick up the equipment and turn it around arranged in the manner you choose....DaveB

Model crane

Hi DaveB,

continuing that thought... Build a model of a crane that is actually operational and grabs the car, lifts it and allows the loco to pass.

Have fun!

Short v2

Another version of shortest would be one switch, with the diverging route a spur just long enough to hold 1 car and built on as tight a vertical curve as you can get.  The GP40 shoes one car up on the spur, sets a brake, goes past the switch, the first car has the brake released and rolls down behind the GP40.   The GP40 puts the 2nd car up on the spur, repeats the process.  The cars are now on the other end of the GP40.  Depending on how you want to measure "length", the main track length is only the length of one switch to the clearance point.

Another solution

Get a second GP-40 and stick it on the other end - no runaround needed at all.

This is a prototypical solution - the Grafton & Upton is using it on the Milford - Franklin line they just took over operation of from CSX.  The Providence and Worcester uses it on some of their locals as well.

Didn't the "Timesaver" have

Didn't the "Timesaver" have about the shortest run around possible for the equipment that ran on it? 40 footers?