Mass Transit Comes to the Desert
Phoenix, Arizona’s new Metro Light Rail system has proven immensely popular with its many modern features.
By Mary Holden
Railroad engineers man these trains, but a group of the other kind of engineers gave birth, breadth, and depth to the light rail system in the Valley of the Sun. Even passengers like me without a background in engineering can appreciate all that makes the track, vehicles, stations, amenities, and power supply for this transit system operate so well. Since opening in late 2008, the initial 20-mile segment running from north Phoenix to nearby Mesa, skirting Phoenix’s Sky Harbor Airport near the mid point, has proven so successful that plans for expansion are already underway.
This comes as part of a trend of light rail systems sprouting around the country. Other systems have been built or are planned in Salt Lake City, Utah; Norfolk, Virginia; Charlotte, North Carolina; Houston, Texas; and Tampa, Florida. The reasons taxpayers have bought into them range from minimizing sprawl and encouraging denser growth in urban areas to spurring development and economic growth.
Living in Phoenix, I’ve ridden the Metro Light Rail system many times, and I wrote “Riding the Light Rail with Kids” for the January 2009 issue of Raising Arizona Kids magazine that coincided with the start of Metro Light Rail on December 27, 2008. But one of the best experiences for me came when I met the engineers behind the system and listened to them talk about creating it.
Not Built Overnight
Metro Light Rail had a 12-year gestation, beginning with a need for public awareness. In the late 1980s, cars and buses were choking Valley streets with traffic and pollution as Phoenix began a population spurt that makes it one of the fastest growing areas in the country. A group known as Valtrans studied and identified automotive travel patterns.
Next came the question of money. In 1996, Tempe city voters passed a half-cent sales tax initiative to support public transit. A study to examine the feasibility of light rail began and made citizens think about a route to span three cities – Phoenix, Tempe, and Mesa –from the northwest to the southeast. Two years later, the Federal Transit Administration (FTA) gave approval for the preliminary engineering phase.
Enter the engineers. Parsons Brinckerhoff, a consulting firm that has pioneered several light rail systems in the United States, was chosen as the general engineering consultant. Senior Engineering Manager Patrick Fuller oversaw the project and remembers the project’s immense scope. “In total there were 54 design subcontractors. There were five rail line section contracts, the Tempe Town Lake Bridge, the Operations & Maintenance Center, park and ride lots, transit center lots, and two systems contracts that had staggered completion dates for design as well as construction. A lot of communication took place.”
Having been at Parsons Brinckerhoff since 1992, Fuller relished the opportunity to take on such a project. “The project was very rewarding for me personally. Coordinating all the various disciplines was challenging, and I learned a lot in regard to bringing all the disciplines together into one functioning system,” he recalls.
Parsons Brinckerhoff started with the conceptual phase, then they worked through the draft and the final environmental phase and got involved in the preliminary engineering phase. They bid for the final design and won. The company even got involved with ballot initiatives to increase public awareness and raise capital.
In March 2000, voters in Phoenix supported a four-tenths-of-a-cent sales tax to raise funds for public transit. In November 2000, the final alignment of track was approved, and in February 2001, the project opened a community office so the public could learn about the process of implementing light rail. Public input was actively sought and valued.
Local tax revenues opened the door to an appropriation of $75 million in the 2005 federal budget and a Full Funding Grant from its New Starts program in the amount of $587 million. Fifty percent of the funding came from the federal government and fifty percent from Valley taxpayers.
By July 2001, Urban Design Guidelines were published, and in October, the first conceptual images of the light rail vehicles (LRVs) were placed on a website for public viewing. During planning, subsurface utility engineering started, and in December, the Tempe City Council approved the plan for a light rail bridge across Tempe Town Lake.
Construction, engineering, and design then began on plans encompassing 20 miles of track (including extra track to accommodate one-way streets), 28 passenger stations, two transit centers, eight park-and-ride lots, closed circuit TV cameras, noise regulation, a public address system, and all electrical and communication systems. Six different contractors worked cooperatively to install the rail line.
Rail line construction was staggered, but the first priority was to get a roadway into the Operations & Maintenance Center. Next came track section four on Washington Street, the test track. Eventually, Parsons Brinckerhoff shared 50 percent of all engineering, with Gannett Fleming and URS Corporation each sharing 25 percent.
Operations & Maintenance Center Serves as Home
As it was being engineered into reality, the project needed a home. In October 2002, Valley Metro Rail, Inc. was formed under Arizona state law as a non-profit by the cities of Glendale, Phoenix, Mesa and Tempe to do business as Metro. Engineer Brian Buchanan got involved with Metro in 2000 during preliminary engineering. At the time, he was with Gannett Fleming, but he now works for Metro Light Rail at the Operations & Maintenance Center. Both Buchanan and Fuller told me it was great to start from scratch with a new system where they could use lessons learned from other light rail installations.
Buchanan saw the advantage of building this center early on, and he took charge of construction. “Building this facility first was the best and most efficient way to start a light rail system,” he says. “It was built using the height, weight, width, and turning radius of the vehicle specifications, so the cars could be delivered, tested and stored.”
Jay Harper, chief of safety and security at Metro Light Rail, oversaw all specifications for the LRVs. He came to Phoenix in April 2003 from Salt Lake City’s light rail project. Harper explains, “The vehicles were purchased from a Japanese company, Kinkisharyo International. But to sign a contract with Japan on a public project and meet Buy America requirements, the cars had to arrive incomplete in the U.S., so 60 percent or more of the assembly had to be of American origin.”
A basement was designed into the Operations & Maintenance Center, and it ranks as the largest basement of any rail system in the country. It sees use for storage of parts, hoists, extra fare machines, and other accessories. Considering that other rail systems struggle to find appropriate storage space, Harper notes, “We can move materials here very efficiently.”
Vehicles Full of Design Features
The LRVs were designed for use in a desert climate. Bill Kleppinger, project manager with Kinkisharyo International, says, “We built a full-size mockup of the car as a design tool to validate the interior and exterior design.” As an example of one of its design features, bumpers that raise and lower over the couplings became a unique safety feature, and the bumpers have proven crashworthy.
Conditions such as dust, solar load, and extreme high temperature were considered. Engineers at Kinkisharyo provided air conditioning, mitigated solar load by tinting the windows, and figured out how dust would impact maintenance.
A lot of attention was given to the use of wheelchairs in the LRVs, and volunteers who test rode the cars provided input to the engineering team. An automatic leveling system based on air compression senses the passenger load and keeps the LRV level with the platform, a feature designed for ease of use by passengers with disabilities. In each LRV, wheelchair areas are separate from bike storage so no interference comes between the wheelchair bound and up to eight bicycle-toting passengers who can hang bikes vertically. Wheelchairs do not need to be tied down because the alternating current motor helps keep the chairs stable during acceleration or braking.
At present, the Metro Light Rail system has 50 LRVs, but it can accept up to 50 more. Generally, 32 vehicles are in operation on any given day unless operation is increased for high traffic times and special events.
Unique Track Used
Except for the bridge over Tempe Town Lake, the track lies entirely at grade, street level. An embedded track system is unique because it costs more than ballast (railroad) track, but decision-makers chose it because it offers increased safety. Embedded track was used for streetcar systems over 100 years ago, but in the United States, it is found only in Salt Lake City, Houston, and Phoenix.
According to Parsons Brinckerhoff’s Gordon Martyn, senior professional associate technical manager of trackwork, “Rail for embedded track is only made in Austria at Voestalpine, and it comes with specially head-hardened steel.” To eliminate a controversy about the durability of regular girder rail, engineers at Voestalpine were able to make steel to 365 BHN grade hardness. The track Metro Light Rail purchased is known as Ri53N and is encased with a rubber shield that protects from the electrical current going astray. At 5.125 inches in height, the Phoenix rail stands much shorter than other light rail track.
You experience no clickety-clack sound or feel at any point on Metro Light Rail because of a wheel-to-rail optimized ride—just a bit of steel on steel—along rails welded together. Wheels are lubricated by an on-board spray system governed by the car’s GPS system. Martyn reports, “We have a few 85-foot radius curves, but there is little to no squeal after a year and a half of operation.” Martyn oozes passion for rails as evidenced by his amazing background knowledge about everything from railroad history to steel strength.
Riding the Light Rail
Before the LRVs were certified for public use, they endured extensive testing that required a level, flat track to be driven at maximum speed, 55 miles per hour. Cars were towed to the Washington Street section of track to run until they reached “burn in.” In use, the cars usually run between 35 and 42 miles per hour.
Metro Light Rail is powered by electricity; an overhead catenary system of 750 volt high-voltage lines rise 16 feet above the track. Engineers worked to switch phasing of some lines to reduce electromagnetic interference, so electromagnetic emissions are low.
“It would take a large power outage to disrupt service,” says Buchanan. The power supply substations for the light rail are all on a different grid. If power is lost on one track, the tracks on each end can supply power. When power goes out in a station, emergency power keeps lights and digital display on for four to six hours.
What happens when the LRVs come to rest? The miracle of regenerative braking. The energy it takes to stop is recycled back into the battery.
Located in downtown Phoenix, the Communication & Control Center is state-of-the-art, according to Fuller. “It has a gigabyte Ethernet system with 144 strands of fiber optic cable. There are another 144 strands of fiber optic cable for traffic signal communication.” Due to multijurisdictional oversight between Metro and the city governments along the line, the cities retain control over their traffic light systems. The Communication & Control Center serves as the brain of Metro Light Rail.
Ridership data is downloaded automatically from automatic passenger counters (APCs) installed in LRV doors. Since it went into service, Metro Light Rail’s ridership numbers keep going up. During the first two days of service, December 27-28, 2008, more than 200,000 rode the rail. In April 2010 a total of 1,208,924 passengers were counted, a 16 percent increase from April 2009.
In looking back, Pat Fuller recalls, “The opening day of our system was very surreal event for me. I rode the train from end to end several times and was just astounded by all the people and the good comments about the system.” Commuters and leisure travelers headed to events and office workers going to lunch all use Metro Light Rail.
Based on such response, the Metro Light Rail appears here to stay. Extensions to this light rail system over the course of the next 20 years are in the planning stages in the cities of Glendale, Mesa, Paradise Valley, and Tempe.
Perhaps no greater an exclamation point comes than when a train crosses the Tempe Town Lake Bridge, as a switch flips and a series of LED light circuits flash. The lights appear to chase across the bridge as the train goes over, catching the eyes of pedestrians. Indeed, many people have noticed the mechanical efficiency and aesthetic beauty of this system.
Mary Holden, a third-generation Arizonan, is a freelance writer and editor in Phoenix, Arizona and assistant editor of Raising Arizona Kids magazine.
Armed with artificial intelligence, robots are working in recycling facilities to address contamination, safety, and manpower issues
Headquartered in Oak Ridge, Tennessee, engineering firm Process Engineering Associates specializes in one discipline, but they apply it to many types of projects all over the world
Engineers at the FREEDM Systems Center at North Carolina State University are developing solid-state transformers that promise to make the electrical grid more reliable and facilitate renewable energy such as wind and solar
Old dams are being taken down around the country for environmental and safety reasons. In Massachusetts, the story of the Upper Roberts Meadow Reservoir Dam removal project shows the complexities involved and the opportunities for engineers.
Mechanical engineers help with knee injuries by developing computational models to characterize ligaments.