This boarded-up tunnel in the mountains of southwestern Pennsylvania dates back two centuries. It was originally built by Carnegie and Vanderbilt for a nineteenth-century railroad, but hard times resulted in four decades of abandonment. In the mid-twentieth century the re-born tunnel spent time as part of America’s first Superhighway, before a re-routing of the Turnpike resulted in another four decades of abandonment.

Today the Laurel Hill Tunnel is not abandoned; it has been re-purposed as a test facility by an innovative racing organization. Now an “Area 51″ of racing technology, the tunnel was the subject of multiple patents before witnessing a restriction of use by racing sanctioning bodies.

The secret lies in aerodynamics.

cover photo courtesy Greg Hall

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Basis in Rail

In 1881 Andrew Carnegie partnered with William Henry Vanderbilt (second-generation) to commission development for a new railroad system to compete with the Pennsylvania Railroad and connect Harrisburg to Pittsburgh.

The men’s vision called for an excavation of nine tunnels through the hilly region for the South Pennsylvania Railroad (SPRR).

Project construction lasted from 1881 until 1885; the tunneling through Laurel Mountain State Park began in 1883. Two years later, the men had dug 813 feet into Laurel Hill before the financial Panic of 1884 scared away investors and stalled the project the following year.

In mid-October of 1885, a work stoppage letter was submitted to inform SPRR workers the project would cease by the end of the month. The South Pennsylvania Railroad never came to be, and the investment ultimately earned the nickname “Vanderbilt’s Folly.” After the project was abandoned, so were the tunnels for the next fifty-three years.

Carnegie stands in front of South Pennsylvania Railroad Tunnel, 1884 SPRR tunnel interior dig progress circa 1884 SPRR survey crew circa 1883 SPRR survey crew circa 1883 East side, Laurel Hill dig East side, Laurel Hill dig West side, Laurel Hill dig West side, Laurel Hill dig

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The Pennsylvania Turnpike: America’s First Superhighway

Decades before President Eisenhower’s Interstate highways, the ambitious folks of the Pennsylvania Turnpike Commission (PTC) put together plans to build what would become America’s first long-distance Superhighway. This precursor to Eisenhower’s highway system included nearly 160 miles of four-lane travel – the exceptions being the tunnels.

When the PTC was building the highway, it made sense at the time to re-use what the railroads had started nearly fifty years earlier. Rather than grade and pave through winding elevation changes, officials elected to instead finish boring out seven of the railroad tunnels. From 1938 until 1940 workers finished the excavations and paved the tunnels for vehicular use.

On October 1, 1940, America’s first long-distance highway – at the time also known as “the Tunnel Highway” – was opened.

PT tunnel construction, circa 1938 PT tunnel construction, circa 1938 PT tunnel construction, circa 1940 PT postcard, circa 1940s PT postcard, circa 1940s PT postcard, circa 1940s PT’s Kittatinny Tunnel entrance design “TURN LIGHTS ON” for safety Pennsylvania Turnpike after open, circa 1940s PT after open, circa 1940s PT toll booth, circa 1940s PT toll booth, circa 1940s Laurel Hill Tunnel, circa 1940 Laurel Hill Tunnel, circa 1940 Laurel Hill Tunnel, circa 1942

The U.S. Bureau of Public Roads predicted 715 cars would travel the Turnpike each day during the first year. Actual use in the first four days was double the estimates, with 6,000 cars reported to having used the highway.

It participated in what would become an American tradition: The Turnpike’s first weekend saw an onslaught of 27,000 Sunday drivers.

Watch: a 1950’s trip into the Pennsylvania Turnpike tunnels

Since there was no precedent for highway tolling, the PTC was forced to establish their own system. According to former employee Lee Rishel, “There were no toll roads like this, with eight intermediate exits, so we had to come up with a fare schedule.”

The committee decided automobile drivers should be charged a penny per mile, and truckers a little more; by 1955 the Turnpike was assessing trucks by weight.

For the first twenty years the tunnels served the PTC well, and by 1957 the Turnpike had expanded to encompass 360 miles across the state of Pennsylvania.

But eventually there were more cars on the road, and traffic became a problem.

[ Did You Know? The highway portion of Laurel Hill Tunnel is 4,541 feet (1,384m) long. ]

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Clogged Artery Requires Bypass

By the 1960s the bottlenecks created by the two-lane tunnels had become arduous to motorists on the four-lane highway. Studies to alleviate the congestion were commissioned and evaluated by the Pennsylvania Turnpike Commission.

Four of the Pennsylvania Turnpike tunnels (Allegheny Mountain, Tuscarora Mountain, Kittatinny Mountain, and Blue Mountain) were expanded by the addition of a second tunnel (see below).

The remaining three tunnels (Laurel Hill, Rays Hill, and Sideling Hill) were to be bypassed by a more economically efficient, paved roadway. Each of the tunnels except Allegheny Mountain were part of the original South Pennsylvania Railroad system.

[ Rays Hill was the shortest of the tunnels and Sideling Hill the longest. Both were sold to Southern Alleghenies Conservancy in 2001 for $1, and together they now form the Abandoned Pennsylvania Turnpike. ]

Work began on the Laurel Hill 3.1-mile bypass on September 6th, 1962. The bypass route was completed in just over two years, and the three tunnels were decommissioned one by one.

On October 30th, 1964, the highway bypass was activated (pictured in yellow below). The Laurel Hill Tunnel, once a proud piece of the Pennsylvania Turnpike System, was closed.

[ By the 2000’s the Pennsylvania Turnpike spanned 514 miles & averaged 156.2 million vehicles per year. ]

Map it!

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The Lost Highway

After closing, the Laurel Hill Tunnel moonlighted as a firing range and storage facility, but it spent most of the next forty years largely forgotten and unused.

That is until the turn of the century, when the Pennsylvania Turnpike Commission was using the former Turnpike tunnel to store highway salt.

One day in 2003, construction crews arrived at Laurel Hill Tunnel and blocked off both ends. The property was secured and guards were posted.

For months the sounds of construction emanated from the former Turnpike tunnel as bulldozers and dump trucks worked on the site; security guards began making regular appearances.

(click thumbnails to enlarge)

When the dust settled new structures appeared. Large arching metal buildings protruded from the former tunnel entry.

No sign hung above the door, there were no graphics indicating a business or logos tipping off who or what was operating in the tunnel. Curious hikers were, however, treated to several obvious tips:

Stacks of racing tires

Drums of Sunoco racing fuel

The not-so-subtle sounds often heard near the tunnel entry. (click to listen): https://sometimes-interesting.com/wp-content/uploads/2015/05/Laurel-Hill-Abandoned-PA-Turnpike-tunnel.mp3

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Coastdown Tunnel

What is this secret test site all about? In short, to study and evaluate aerodynamics in a controlled environment. An abandoned tunnel provides this with little startup cost and minimal energy use compared to the alternative wind tunnel or other fabricated simulation facility.

Used toward this purpose, it becomes a “coastdown tunnel,” a tool that enables testers to combine real-world acceleration with conventional wind-tunnel aerodynamic testing.

Straight-line testing then becomes possible without temperature fluctuations or wind affecting the results.

It works in reverse of a conventional wind tunnel used in aerodynamic testing, in which air is forced around a static car (pictured below).

In a coastdown tunnel vehicles are driven through the tunnel at speed, and the resultant forces are then measured around the car.

A source close to the tunnel’s operator explains more: “The big thing about the tunnel is the ability to control the environment, making for more repeatable results. It can be heated/cooled to the desired temperature, and, obviously, there are no worries about cross winds.”

The fact the tunnel was a former train passage helps with the typical coastdown tunnel concern of pushing large amounts of air by a rapid moving object; in the early era of trains, this was defeated by digging horizontal tunnels at the main tunnel’s midsection to alleviate air movement. This problem is somewhat muted by the smaller surface area of a race car compared to that of a train.

However the biggest advantage of all is seeing the resulting ducting and operating temperatures of a vehicle running under its own power. With temperature and wind now a constant, testing can commence 24 hours a day and 365 days a year. Those responsible for the facility certainly appreciates the tunnel’s value. “Our temperatures are real, not calculated or simulated.”

AQS Air Quest 1000 dehumidifiers sit at each end of the tunnel to ensure the constant stays constant, while a portable weather station gives the team the pulse of the air quality. To further control this, two sets of doors were installed at either end, acting as an airlock allowing cars to enter and exit staging area without disturbing current test operations.

The staging lights on either end of the tunnel are accompanied by traffic lights hung along the track to offer additional visual aids to the drivers speeding through darkness.

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Laurel Hill Coastdown

The metal garages protruding from the tunnel exit offer cover an area for loading and unloading of racecars. Nearby are staging areas and workshop. Once a car is inside, it then passes through the main tunnel door which is sealed behind the car.

Tunnel drivers wait for the light-tree to show green before accelerating to the desired testing speed. Once the speed is reached, the car maintains the velocity for short period before coasting.

As the vehicle passes beacons inside the tunnel, measurements are taken. At both ends of the tunnel are turntables which allow test vehicles to quickly reverse direction.

Current configuration offers a 1,510-foot (460m) acceleration zone, which, depending on the car, gives test subjects a potential top testing speed eclipsing 150 miles per hour (241 kph). Test engineers have not forgotten braking – there is a 1,510 foot deceleration segment on the other side of the tunnel which doubles as the acceleration track for the return trip. The remainder of the natural tunnel’s length is occupied by the turntables and staging areas.

Testing goes beyond single-car-experimentation. Multi-car tests include single-file (drafting) and side-by-side methods.

(click thumbnails to enlarge)

images courtesy racecar-engineering.com

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The Operator

Laurel Hill is currently being used by Chip Ganassi Racing, run by Floyd “Chip” Ganassi, Jr. (pictured). Once a budding driver himself, Chip eventually realized his skills better served him with developing technologies, managing drivers, and running a racing team.

Since he made the switch from driver to entrepreneur and team owner, Chip’s accolades and accomplishments have only grown. During his first year in NASCAR (2001), Ganassi’s driver finished third in Cup standings. Between 2008 and 2011 he won all four of the crown jewel races of North America: The Daytona 500, the Indianapolis 500, the Brickyard 400, and the Rolex 24.

Chip Ganassi was the first team owner with four consecutive championships in CART (1996-1999) and IndyCar (2008-2011). He also has seven Daytona Prototype championships, five Grand-Am championships, or 159 total race victories on Ganassi’s resume.

But even Chip will admit it takes more than luck and money to win. In competition drivers are separated by milliseconds. Driver skill is important, but every variable can alter lap times. Canards and wings affect a vehicle’s handling and drag; tire inflation pressures can affect grip, rolling resistance, and wear. From the diameter of your air intake to the drag created by underbody cavities, everything matters.

Chip might be on to something with this tunnel.

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Discovery

Laurel Hill was not the first tunnel Ganassi had scouted. Chip and team engineer Ben Bowlby had looked into a shorter tunnel near Pittsburgh first, however it wasn’t long enough.

Chip explains the choice of a tunnel:

“My engineers told me, ‘We need a drag strip—let’s buy an old drag strip or air strip, and if there is still budget we’ll build some walls, and if there’s more budget we’ll put a roof on.’ I asked if a tunnel would work and they said, ‘maybe better.’ And I said, ‘Good, because I know where there’s a tunnel, so let’s see if we can get that.‘

When the men from Ganassi Racing examined the Laurel Hill Tunnel in September of 2003 they found it a mess. One side was stacked with salt, the other with assorted road-making and service materials.

Only known photos of Laurel Hill Tunnel before Ganassi Racing:

source

It was dark, dirty, and neglected. So naturally they cleaned it up and ran a NASCAR stock car down the tunnel. “We checked the influence of the tunnel on the airflow of the car running at 150 mph just to see that we weren’t completely mad” reported Bowlby.

The wheels were in motion. By January of the following year the old highway had been graded & resurfaced, the tunnel exits had been sealed, and generators installed to offer systems power. It worked, but it was crude. “It was simply a sealed, one-mile long tunnel.”

For years the racing team enjoyed a largely secretive operation that did not seem to generate much discussion outside of industry insiders or local residents. But even these groups admit their knowledge was limited to the existence of the operation, and in most cases little more.

More interested, was the public-at-large. Smaller sources reported the findings first: A former iteration of the Rays-hill.com website discussed theories of what was occurring at the tunnel and included pictures sent in from hikers in December of 2005.

A post on Autoracing1.com in June of 2006 was another public reveal discussing the tunnel, followed by a Racecar-engineering.com article posted on Speedtv.com in December of 2007.

By this time the tunnel’s existence was no secret to the racing industry, but it had still largely failed to grab the public’s attention until sometime in 2009, after another hiker shared pictures online of the Laurel Hill tunnel with its new metal garages.

In 2010 a former employee who worked in the tunnel and was later terminated sued the company over his experience.

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Driver Experience

Several former Ganassi Racing drivers have shared their experiences at Tunnel 51, which both sheds light on what occurs and removes a bit of the shine behind the mystique. Most notable of Chip’s former wheelmen to share stories was IndyCar driver Darren Manning. He did more than drive in the tunnel.

“Yeah, I drove in the tunnel. In fact, I crashed in it.”

Manning has an intimate familiarity with Laurel Hill Tunnel, having performed dozens (if not hundreds) of runs up and down the indoor track. “I climbed 12 feet up the wall and slid down on my side. I nearly did the full loop on the thing.”

“Have you ever seen the TV show Battlestar Galactica, when those spaceships were shot from a tube? That’s what testing in the tunnel was like.”

Darren’s job was to accelerate to 140 mph as fast as possible, then coast until he hit the other end. At that point he’d drive onto the turntable, spin around, and repeat the process. Rinse, repeat. In between runs he’d play a Game Boy.

The test car was equipped with telemetry systems and special clutches to decouple the drive shafts from the wheels. During one test, one of the wheel clutches failed and locked the wheel, sending Darren into and up the wall.

“I’d been in the car for, like, seven hours, bored senseless and not really expecting a crash. Then all of a sudden, the f**king car’s doing an S-bend at 140 mph and I started climbing the wall…“

Darren also points out the low tunnel temperatures combined with moisture on the track and cold tires creates a serious problem for traction. Manning’s stories lack the top secret flair of an Area 51 adventure, but they sounded equally as hazardous to one’s health.

If there’s one thing the wheelmen agreed upon, it was the fact the tunnel was “a test driver’s nightmare.”

“Our drivers think it’s cool the first time. Then they’re arguing over who doesn’t go back.”

– Tim Cindric, Penske Racing president

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Real-World Advantages of Testing

One benefit of tunnel testing Manning learned firsthand was the effects of deforming bodywork, both at speed and after collision. Bodywork deforms during races. As Robert Duvall reminded us in the 90’s film classic Days of Thunder, “rubbin’ is racing.”

Small variance in bodywork after in-race collisions can have a cascading effect on a car’s overall aerodynamic profile. “You have to remember that the cars are all extremely close,” adds Darren Manning. “Five pounds less drag or 20 pounds more downforce has a huge cumulative effect over the course of a race.”

Laurel Hill’s first practical testing came in 2004 with the development of the G-Force Indycar (pictured). That year Italian chassis manufacturer Dallara had developed a new airbox. According to team engineer Ben Bowlby, Ganassi Racing didn’t expect the airbox to be approved for use in their competition, so the team opted to not research the intake.

This proved to be a mistake, admits Bowlby. “When we had gone to the first IRL open test of 2004, we were something like six miles an hour off the pace. The redeveloped airbox meant that the car was fully competitive. If we had gone the CFD route or via a scale-model wind tunnel, I don’t think we would have got it sorted out in time.”

Laurel Hill Tunnel allowed the team the ability to test the product and deploy it rapidly.

“Ganassi’s success at the superspeedways, where aerodynamics play a bigger role, suggests the team has a technical advantage from having its own facility .”

– Tim Cindric, Penske Racing president

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Patents

It’s unlikely Andrew Carnegie considered racing patents one hundred years in the future when he commissioned the Laurel Hill Tunnel dig, but today that is one of the tunnel’s primary contributions to its current tenant.

In 2006 Chip Ganassi and Ben Bowlby were awarded four U.S. patents (US 7131319 B2, US 7305870 B2, US 20060053873 A1, and US 20070000315 A1) on the design and implementation of a “method and apparatus for testing a moving vehicle” in the mold of Laurel Hill.

Reasons for secrecy go beyond the patents. History in racing is unfortunately spotted with many examples of advancements and technologies being banned in the name of more even competition. Why risk losing a valuable edge by bragging about it?

To Chip’s credit, he smartly downplays the existence and importance of the tunnel – but he’s quick to point out “It’s not a secret tunnel. It’s a private tunnel.”

“Every team has a tunnel. Ours is just different, maybe more unique.”

– Chip Ganassi

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Yet the tunnel is secret enough to warrant a higher level of clandestine behavior – even from parties not involved with its operation. When Road & Track magazine asked the Pennsylvania Turnpike Commission for tunnel ownership information, they asked “why do you need to know?”

This was promptly followed by a phone call from Ganassi’s public relations officer asking the car magazine to leave the story alone.

Years of this secretive behavior had earned the site the nickname “Ganassi’s Area 51.” Then during a September 2012 interview in Autoweek magazine, Chip Ganassi publicly acknowledged the tunnel’s existence in the press with a defending statement:

“It’s not a secret. It’s not incumbent upon me to publicize how we test, but it isn’t a secret.”

[ Les Mactaggart, Indy Racing League’s technical director, knows of only three teams that use straight-line testing: Ganassi, Penske and Andretti Green Racing, which have won 43 of the past 44 races and the past five championships in the IRL. ]

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Present Day

Today weeds extend from the cracks in the pavement and stacks of racing slicks still stand stacked near the entrance, as do drums of racing fuel. In the racing industry it is not a secret.

Years ago Toyota’s former F1 team used the tunnel. IMSA cars have been reported testing inside, and there are non-competing teams who subcontract use of the Laurel Hill Tunnel from Ganassi.

Ganassi Racing has enlarged the tunnel in the years since opening and still uses the tunnel for testing – although any competitive advantage for 2015 was neutered when IndyCar and NASCAR decided to reduce time in which teams are allowed to spend testing in such environments. IndyCar reduced time to fourteen days per season; NASCAR banned testing outside its own events.

Tunnel testing has made its way to England, where in October of 2014 one company announced it would convert the unused 1.7-mile Catesby railway tunnel into a vehicle test facility. Aero Research Partners claim the tunnel should be operational sometime in the next couple of years.

Watch: Sounds from Laurel Hill Tunnel

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Ownership

Who owns the tunnel? We can make an educated guess the Pennsylvania Turnpike Commission is still financially responsible for it in some way, shape, or form.

According to this Commission document filed for fiscal year (FY) 2005/2006, the Laurel Hill Tunnel had approximately $100,000 budgeted for “Tunnel inspection” in both FY 2007-2008 and FY 2012-13 (see below).

Oddly, the situation changed soon after this budget was published. The next year’s budget (2006-07) still reflects the Laurel Hill maintenance in 2012-13 – but the 2007-08 expected $100,000 maintenance charge suddenly disappears.

Then this document, which reflects the same budget for the following year (2007-2008), also shows no Laurel Hill Tunnel maintenance charges for the current year, but it still reflects the tunnel’s 2012-13 future charges.

It would not be a wild assumption that when Ganassi Racing leased the tunnel, it might have allowed the PTC to wipe out that $100,000 maintenance requirement since his crews were cleaning out and re-fitting the tunnel anyway. If true it was symbiotic; the PTC wasn’t using the tunnel and the budget commission wouldn’t flinch at an opportunity to save $100,000.

Additionally, it is unlikely the Pennsylvania Turnpike Commission would continue to pay for inspections if it did not maintain an interest in the property.

While we don’t know who officially owns the tunnel, Ganassi admits that he controls the tunnel and is willing to make it available to other entities that can benefit from its use.

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Map it!

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