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Big 10 Curve and Rocky Flats


Rocky Flats is a large mesa right at the foot of the Flatirons and the Front Range of Colorado west of Denver. The flats are known for their extreme winds which can cause white out conditions in the winter and strong gusts in the summer that can blow cars and trucks off the road. Subsequently there are a few windmills located here that are part of the National Wind Technology Center which uses these gusts to help test and measure phenomena associated with the burgeoning renewable energy sector.

Big 10 curve is a unique railroad engineering marvel that might be the Front Range equivalent of Tehachapi or Horseshoe Curve. It’s a unique solution around the natural landscape that take the rails from the Rocky siding in the bottom of the wash to the Clay siding at the top. To gain the elevation, the rails need to wind around two 10 degree curves while also rising at a grade over 1.5%. This makes for amazing sightseeing and railfanning as a long train could be visible in three different areas as it winds through. Along with the tight curves and steep grade, the winds on Rocky Flats also posed a challenge for engineers. After losing cars to derailments related to gusty winds, the railroad installed a series of hopper cars filled with concrete, rocks and dirt that stand as a wind block to protect the tracks in the most gust prone area of the curve. A unique solution that still stands as a effective block to the extreme winds that the area is known for.

Possibly the most notable history of the area is the history around the Rocky Flats Plant. The plant was created in the 1950’s to manufacture plutonium pits, a trigger for nuclear weapons being developed by the US Military. Between 1952 and 1999 the plant manufactured components using radioactive materials that were delivered and removed by the siding here known as Rocky. The railroad was a key component in the supply of these materials and the transport of the completed components and waste from the plant. In 1999 the plant was raided by the FBI and the EPA after several violations in years past regarding contamination and release of radioactive materials into dust and ground water. The site went through an extensive clean up and parts are now a wildlife refuge. The railroad no longer serves any facility on that property, although sometimes visits the gravel plant just to the north.

The Layout Model

We have taken the time to model the Rocky Flats areas as accurate as possible given the limitations of our layout and size. We have made sure to include the marquis tight curves and grade in our model while also including both the Rocky siding and the Clay siding. We also made sure to pay homage to the Wind Technology Center by adding the iconic large windmills as well as the Rocky siding. Occasionally you can even spot a glow in the dark “Radioactive” car parked on the siding as a homage to the history of the real life location.

The windmills and a view of the Rocky siding as well as the hopper cars in the distance. Looking railroad west.

Being one of the longest siding on the layout and being near the bottom of the “hill”, Rocky siding is often busy with long trains passing here before heading into North Yard or up the grade towards the Moffat Tunnel. On operation days, take a look to the one of the two 65 car coal trains that fill almost the entire siding here as they wait on passenger or higher priority trains that might sneak past.

Here is a view looking railroad west highlighting the curves. The panel in the foreground allows operators to see the alignment of switches along this section. Switches for the Clay siding are in accessible behind the scenery and hard to see, thus the need for the display.

With the scale and depth to the scene, a large chunk of track is not reachable from the main aisleway. We still need access for scenery, cleaning and the occasional derailment. We have built two secret lift out sections into the scene that offer access when needed. Now these are easy to open, but the process of crawling under the layout is never fun so we do our best to avoid any issues.