Any such thing as a roundabout junction?

[DSchmitt]

FM is correct about the purpose of roundabouts

Interchanges are not normally considered an alternative to a roumdabout no matter how much space is available.  Interchanges are used on high speed (usually) access controlled Highways.   Round abouts are used on low speed local roads (usually) as an alternative to traffic signals or STOP signs. The puropse of traffic signals and STOP signs is to reduce conflicts.

 

[Anonymous]

Obviously CD you're being contrary soley for the sake of sophomoric kneejerk reactionism.  The roundabout's purpose is exactly what I stated.

 

Posted by CrazyDiamond

"FM, you're wrong about the purpose of steeet roundabouts......there are many ways to prevent right-of-way conflicts.....a roundabout's sole purpose is to allow very high-capacity traffic flow of an intersection where signs and/or signals would bottleneck the intersection AND where space is too limited to build a conflict-free interchange."

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http://www.roundabouts.net/index.html

Yeah I know... I read through that info a couple of years ago.  I didn't say roundabouts don't reduce points of conflict.  I said that is not its purpose which is what FM said. Reducing conflict points is a benefit of roudabouts, a safety benefit to be specific, but that is not its purpose. When space is available engineers will often choose an interchange over a roundabout...unless the space is just not there.

The purpose of a street roundabout is to prevent right of way conflicts by forcing all traffic to move one circular direction.  For railroads, if the purpose is to avoid at grade diamond crossings, it'd be a lot cheaper to construct an elevated grade separation than some mile wide circle of tracks.  And yes, a lot less real estate.

[Anonymous]

In Taneytown Maryland a failing intersection was paved over and converted to a round about.

It seems during evening rush thousands of cars stack up waiting to make a right turn for miles at that intersection. The roundabout makes everything move slowly thru.

[CrazyDiamond]

Posted by CrazyDiamond

"FM, you're wrong about the purpose of steeet roundabouts......there are many ways to prevent right-of-way conflicts.....a roundabout's sole purpose is to allow very high-capacity traffic flow of an intersection where signs and/or signals would bottleneck the intersection AND where space is too limited to build a conflict-free interchange."

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http://www.roundabouts.net/index.html

Yeah I know... I read through that info a couple of years ago.  I didn't say roundabouts don't reduce points of conflict.  I said that is not its purpose which is what FM said. Reducing conflict points is a benefit of roudabouts, a safety benefit to be specific, but that is not its purpose. When space is available engineers will often choose an interchange over a roundabout...unless the space is just not there.

The purpose of a street roundabout is to prevent right of way conflicts by forcing all traffic to move one circular direction.  For railroads, if the purpose is to avoid at grade diamond crossings, it'd be a lot cheaper to construct an elevated grade separation than some mile wide circle of tracks.  And yes, a lot less real estate.

[Poppa_Zit]

Posted by CrazyDiamond

"FM, you're wrong about the purpose of steeet roundabouts......there are many ways to prevent right-of-way conflicts.....a roundabout's sole purpose is to allow very high-capacity traffic flow of an intersection where signs and/or signals would bottleneck the intersection AND where space is too limited to build a conflict-free interchange."

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http://www.roundabouts.net/index.html

Plus, buying a handful of stopor yield signs is a helluva lot cheaper than buying and maintaining traffic signals, not to mention the electric bill.

[DSchmitt]

Posted by CrazyDiamond

"FM, you're wrong about the purpose of steeet roundabouts......there are many ways to prevent right-of-way conflicts.....a roundabout's sole purpose is to allow very high-capacity traffic flow of an intersection where signs and/or signals would bottleneck the intersection AND where space is too limited to build a conflict-free interchange."

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http://www.roundabouts.net/index.html

[Poppa_Zit]

Here is a landing at Midway.

http://www.youtube.com/watch?v=J1ikOmJxzac

There are railyards a-plenty near the airfield.

You betcha. If you add up all of the acreage of train yards in the Chicago area, it comprises an area greater than the state of Delaware. Chicagoland also has more at-grade street crossings than any other geographic area in the world.

[Anonymous]

Here is a landing at Midway.

http://www.youtube.com/watch?v=J1ikOmJxzac

There are railyards a-plenty near the airfield.

[CrazyDiamond]

Last time I looked, wyes worked pretty well and don't gobble up so much real estate.

The purpose of a street roundabout is to prevent right of way conflicts by forcing all traffic to move one circular direction.  For railroads, if the purpose is to avoid at grade diamond crossings, it'd be a lot cheaper to construct an elevated grade separation than some mile wide circle of tracks.  And yes, a lot less real estate.

Maybe the objective/purpose is to:

• Merge multiple wyes and/or crossings together.
• Eliminate (not to be confused with avoid) crossings.
• Simplify interlocking and routing logic.
• Allow for train turn-around without any backing up.

FM, you're wrong about the purpose of steeet roundabouts......there are many ways to prevent right-of-way conflicts.....a roundabout's sole purpose is to allow very high-capacity traffic flow of an intersection where signs and/or signals would bottleneck the intersection AND where space is too limited to build a conflict-free interchange.

[Anonymous]

Last time I looked, wyes worked pretty well and don't gobble up so much real estate.

The purpose of a street roundabout is to prevent right of way conflicts by forcing all traffic to move one circular direction.  For railroads, if the purpose is to avoid at grade diamond crossings, it'd be a lot cheaper to construct an elevated grade separation than some mile wide circle of tracks.  And yes, a lot less real estate.

[mudchicken]

Last time I looked, wyes worked pretty well and don't gobble up so much real estate.

[Poppa_Zit]

Thanks for the additional info, Paul. I didn't realize IHB had abandoned east of Narragansett. It seems like the only trains I ever see going around Midway have IHB power. 

[CSSHEGEWISCH]

65th Street is the last east-west public street along the north edge of Clearing Yard.  69th Street as indicated on the photo map is NOT a public thoroughfare.  At the west end of Clearing, you can take Old Harlem Ave south from 65th Street to an east-west roadway called Belt Circle that parallels the west yards.  Excellent shots can be had from this roadway with a long lens.

[MP173]

I noticed on the current view of Clearing a 69th street that is along the north side of the yard...is that a public street?

ed

[CSSHEGEWISCH]

Actually, two railroads were re-routed with the expansion of Chicago Municipal Airport.  The BRC 59th Street line and the IHB Stock Yards branch ran parallel to each other from about Narragansett Avenue east to the BRC main, two double track mains side by side.  The IHB line east of Narragansett was recently abandoned, replaced with trackage rights over BRC.

[PBenham]

 Mr.Spock (Star Trek) said it best: fascinating. Midway Airport is really shoehorned into its space. Betcha IHB (NYC) made some nice coin off that deal. But then again...

There are/were some loops, but not as part of junctions, strictly speaking. The best known example of that is on UP (SP) at Colton CA. Which is a one way yard. A friend of mine, ex-Conrail,  now with UP said there is only one direction of traffic at Colton: IN-then it is never to be seen again as it has traveled to that place we know by the name of "the Twilight Zone!"

[Poppa_Zit]

A little more geography on the Clearing Yard picture:  63rd Street runs along the top edge of the photo, Central Avenue is north-south on a line with the crest of the hump and between the balloon tracks that go under the hump.  71st Street is the small street along the south that abuts the south part of Stickney's Circle.  Municipal Airport is located north of 63rd Street between Central and Cicero.  The current CSX intermodal terminal is along the south edge of the yard west of Central.  The remainder of the circle that shows in the picture has since been flattened with a Commonwealth Edison switchyard/substation on the site.

Thanks for the additional info. I grew up about 3 miles north of Chicago Midway Airport, in Cicero, but in those days the canal was a "dividing line" and we never went to the far South Side -- so my knowledge of that area is not very good. Not even today.

I do know at the north end of Municipal Airport was located Laramie Country Club, as I knew an old gent who caddied there in the 1920s. It was south of 55th Street and north of 59th Street (then the C&WI RR) at Laramie Avenue. It became a victim of sprawl as the airport expanded to twice its size.

The Chicago & Western Indiana Railroad (current Indiana Harbor Belt) right-of-way was also moved as the airport needed to expand in the late 1930s. The C&WI ran east to west straight along the north border of Municipal Airport, as it was then called before the name change in 1949. Of course, the railroad it could not run through the proposed one-square mile airport tract, and only after a long, fruitless wait for railroad permission, a 1941 court order finally forced its move to its present location.

Here's a 1938 aerial photo showing the railroad intersecting Midway runways, which had already partially been constructed in anticipation of the tracks being relocated (you can see the roughed-in right-of-way at far left, graded but no track laid). The original airport was entirely south of the tracks:

Pop Z  

[CSSHEGEWISCH]

A little more geography on the Clearing Yard picture:  63rd Street runs along the top edge of the photo, Central Avenue is north-south on a line with the crest of the hump and between the balloon tracks that go under the hump.  71st Street is the small street along the south that abuts the south part of Stickney's Circle.  Municipal Airport is located north of 63rd Street between Central and Cicero.  The current CSX intermodal terminal is along the south edge of the yard west of Central.  The remainder of the circle that shows in the picture has since been flattened with a Commonwealth Edison switchyard/substation on the site.

[CrazyDiamond]

Cool pictures!

[Tulyar15]

Obviously the size of the circle would be fairly large, but such a junction would be pretty impressive......all tracks (and there could be a large number of them) lead to a large track circle. A train on any track can be 'switched' to another track with only two switches needing to be controlled....the entrance switch and the exit switch. So does such a thing exist anywhere in the world? .

In Birmingham, England the Soho - Perry Barr "loop" line effectively forms a large circle with the original Grsnd Junction line, with New St. station on part of the loop. Also on the south side of the city the Lifford Curve forms a second circle. Some of these curves are only used for diversions when other lines are closed for track repairs, but they do provide useful contingency in such cases.

[Poppa_Zit]

The history of the Clearing Yard is interesting and is found in a fascinating story of a practical railroad dreamer who lived in the days of empire builders. His name was Alpheus Beede Stickney, and was a lawyer-turned-railroad magnate. Stickney was president of the Chicago & Great Western Railway, whose line reached Chicago in 1886.

He conceived an enormous clearing yard for the ever increasing flow of freight which he foresaw for Chicago when its distribution facilities had been exploited. His first thought was location and his first requirement was a site outside the city where the burden of taxation could not eat away the economical advantages of his clearing yard.

In 1889 he proceeded with the construction of his conception of a clearing house for railroad cars. This was a four track circle, a mile in diameter, into which he proposed to have the railroads feed their freight trains at different intervals, dropping off cars destined for other railroads into radial tracks and shunting those for industries upon tangent spurs.

After much thought, Stickney decided upon the clever name "Clearing Yard" and thus gave the name Clearing to the industrial district which was to be its ultimate successor. This circle ran from 55th Street on the north to 79th Street on the south and from Harlem Avenue on the west to Cicero Avenue on the east.

The plan was found to be impractical and never reached a tryout stage. So Stickney passed out of the picture and his circle went back to nature. You can see a faint outline of the circle in the middle of these 1938 U.S. Government aerial survey photos. The land which is now Chicago Midway Airport is at the upper right. In addition to the runways, there also was a golf course on the site. The curved street at the far left is Harlem Avenue; the street on the far right is Cicero Avenue.

And here it is today:

http://local.live.com/default.aspx?v=2&cp=41.767888~-87.770551&style=h&lvl=15

Then for years, 4,000 acres lay idle, but not forgotten. H.H. Porter, another of the empire builders, a railroad president and banker, picked up where Stickney left off. In 1898 he laid out a car sorting yard employing the hump gravity principle for the first time on a large scale.

The yard commenced operation on April 1st, 1902, and Mr. Porter invited the railroads to come and use it. Despite his position as chairman of the Chicago & Eastern Illinois Railroad, he was unable to convince his fellow railroaders of its practicability or to agree to its cooperative use. The Yard remained in general operation for one month only, but continued to handle some switching business on a small scale until August 1912. In order to fit into Belt Railway plans of terminal operation, it was necessary to tear out, salvage, rebuild and enlarge. It took the years 1913, 1914 and part of 1915 to do it.

Source information from: Belt RY of Chicago

[CShaveRR]

I stand corrected by the article in the September 1966 issue (October contained the second part).

The circle was in fact built, during the 1890s--I can't even picture where it would be.  There would have been 20 yards surrounding it, according to the original plan--one of these became Clearing.

I'd have to guess that much of the town of Summit was built over where the circle was.

[CShaveRR]

Clearing was the place--but I'm not sure that the circle was more than a concept--it was to have a number of yards around it, only two of which were actually built and employed in the present yard.

Trains had a two-part article on the BRC back in the 1960s, that showed this concept.

There really would be no reason to employ such a method of classification.  On the other hand, some belt railroad companies like the Toledo Terminal had a circular route, albiet on a much larger scale.

[nanaimo73]

One of the big yards in Chicago had a big circle in the middle, perhaps Clearing, 100 years ago ? 

[CrazyDiamond]

Obviously the size of the circle would be fairly large, but such a junction would be pretty impressive......all tracks (and there could be a large number of them) lead to a large track circle. A train on any track can be 'switched' to another track with only two switches needing to be controlled....the entrance switch and the exit switch.

So does such a thing exist anywhere in the world?

I'd also like to see pictures online of large 'crossbar' junctions....the ones where a train can proceed straight through, or be switched left or right onto a 90 degree perpendicular track, and a bunch of these exist to essentically form a large crossbar style junction.....so please post links if you know of em.