All aboard

All aboard! Las Vegas Monorail Project

Set to open in 2004, this privately funded, non-profit project will connect almost 25,000 hotel rooms and 4.4 million sq. ft. of convention space with nearly four miles of fast, clean and efficient transportation.

by Clair Urbain

Building an elevated monorail line anywhere is difficult, but constructing one in a city that never goes to sleep and won’t tolerate business disruptions makes the Las Vegas Monorail project extremely daunting.

“This is the first monorail our company has ever done,” says Andy Sorensen, field engineer for Granite Construction Company, which has had extensive experience in building highways, dams, and bridges. “All components must fit exactly. We have a tolerance of only +/-1/16” in 5'. Many of the components are prefabricated off-site so measurements and processes must be perfect.”

The project is divided into 21 segments made up of five to seven spans of monorail beams. The first step requires coring column supports which are 6' in diameter and 20' to 40' deep. They are cut with a computer-controlled drill that returns the rig to the exact position it started, allowing crews to change drilling tools without spending extra time realigning the rig with the hole.

“We often must use a coring barrel with 56 carbide teeth to cut through the caliche,” says Sorensen. The drilling rig can exert more than 12,000 psi. Sometimes, the clay is so dense it gets jammed in the drilling barrel and must be jack-hammered out with a hoe-ram.”

In sandy soil, the crews use a 6’ auger to cut through the soil profile. Typically, crews can complete one or two shafts per day, depending on drilling conditions.

“Even with underground utility locating services, it’s amazing what we run into when we begin sinking the shafts. In the early days of Las Vegas, they didn’t mark things very well,” Sorensen says.

Once the shafts are drilled, crews drop in a prefabricated rebar cage, pump out excess ground water, and pour the caisson.

“These caissons must be placed exactly because the precast beams rest on them and must be within tolerance so the monorail cars can ride on them smoothly,” says Todd Walker with the Las Vegas Monorail Project.

Precast precision
Once the caissons are poured, a guideway support system is built on top of the caissons. No two columns or track supports are exactly alike. Due to space constraints, some are designed as cantilevered columns; some have a straddle-bent design that straddles the roadway; others have a simpler hammer-head design. Depending on the design, different concrete mixes are used. Track supports are then post-tensioned to the engineering specification.

A variety of column designs are needed to support the monorail to meet traffic, property line and clearance issues.

All monorail guideways are precast at a facility 10 miles north of Las Vegas.

“Concrete is the only material that can make these unique structural shapes,” Sorensen says. “We have no shortage of aggregate around here, and concrete offers a smoother riding surface when compared with steel track.”

The precast yard is in the middle of the desert. The yard has three jigs that crews use to custom-bend the rebar for each guideway beam. Once the rebar is in place, crews form up the beam, then pour concrete.

Engineers discovered that the extreme highs and lows of desert temperatures can cause the forms to expand and contract, affecting the tolerance of the beams. To help minimize that, curing is closely monitored with a computerized system that tracks concrete temperature and sends signals to adjust the temperature of the forms.

“There are four lengths of heating coil on each side of the form,” Sorensen says. “The computer records bed temperatures throughout the length and increases or decreases heat to maintain a constant temperature throughout the concrete. It prints out a report after the cure and even does self-diagnosis if something isn’t working right. The test cylinders are also controlled by this system so they cure under the same conditions as the beams. This really is very simple, efficient and dependable.”

Making the move
With little room on the right-of-way to store the guideway sections and with heavy Las Vegas traffic, crews usually must move the sections into the construction zone only on early Sunday mornings.

“We have six trailers with rear-steering axles, and we can move in about 12 each week before traffic gets too busy,” says Sorensen.

The spans are from 60' to 119' long and are very asymmetrical, so lifting each one is slightly different.

Once unloaded, lifting clamps are placed on the beams and two cranes hoist the spans in place.

“The crane subcontractor works closely from the plans to figure out the best crane locations to do the pick. He writes up a lift plan and circulates a copy to everyone. Once the lifting clamps are in place, the contractor does a short lift to assure the span can be lifted accurately and safely. The clamps often have to be realigned to get the balance correct. Each pick is a little different because each beam is a little different. In some cases, it has led to ‘spontaneous engineering’ to attain the correct span placement,” Sorensen says.

To maintain the tight tolerance of the project, precast yard workers survey off of a tower that sits on a thermally insulated shaft in the ground.

“We can get from 5/8" to 3/4" form movement from the sun. That makes it hard to achieve our 1/16" tolerance in 5' requirement.” Sorensen says.

Mules aid construction
Almost all of the construction work takes place on the elevated monorail guideways, so workers must have effective fall protection.

Contractors have built "mules" that ride the guideways, offering workers platforms that allow them to work with less bending and reaching.

“We require 100 percent tie-off where falls are a danger. However, some contractors have simplified fall protection by building ‘mules’ that ride along the monorail guideways,” says Walker. “The mules allow workers to stand up in a supported platform that rides on top of the monorail guideways. It puts the work at the workers' chest level instead of having them lean over the guideway. It’s more comfortable and provides them with the fall protection they need,” says Walker. “Some of the units are motorized, so they can be easily moved along the guideway.”

Construction hazards
People and traffic are the greatest challenges to this construction project, followed closely by rain.

“This is a busy city and people are here to have a good time. They are everywhere at all hours. We have to make sure that construction areas are well-protected so visitors can’t get into the work areas,” says Sorensen. That means better fencing and barriers, and at times, a security team.

For example, the monorail route runs along Paradise Road and Sands Avenue. Although workers must use part of the roadway to build the monorail guideway, traffic must still be able to flow. It often means moving traffic barrels for peak travel times when people are going to or from the convention center. To do this, it can take as many as 70 man-hours. “The roads must stay open. The only time they will close is for large span lifts, and those are planned to take place early in the morning and to take as little time as possible,” says Sorensen.

Rain is also a problem. “When it rains here, it is quick and big and can quickly fill excavations and ruin buildings opened up for construction. We have people on rain watch 24 hours a day, and if it looks like it’s going to rain, we move fast to set up teams that can cover work, run pumps, man mops and control the damage,” says Sorensen.

The story behind the monorail
Within a four-mile corridor that stretches from the infamous Vegas strip to the Las Vegas Convention Center, there are nearly 25,000 hotel rooms and 4.4 million sq. ft. of convention space in nine facilities, says Todd Walker of the Las Vegas Monorail Project. More than 35 million visitors come to Las Vegas annually, and projections show that number will climb.

“We project more than 55,000 riders a day and expect to move approximately 20 million passengers a year,” he says.

Today, waits for cabs at the convention center can take as long as two hours. “When the monorail is in operation, the ride will be 14.4 minutes, including all stops,” he adds.

First private mass transit project
The monorail began in 1995 as a private project that connected the MGM Grand and Bally’s hotels and casinos. It effectively spanned the one-mile gap between the southside MGM Grand hotel and casino with the Las Vegas Strip. It proved successful, moving 6 million passengers a year. It was a good experiment that helped prove the viability of a mass transit system and will be incorporated into the new monorail system.

It also helped business. “Bally’s saw revenues jump 10 to 15 percent from the increased foot traffic brought in by the monorail. In 1997, the vision to create a connection from the convention center on the northeast side of the Strip with the one-mile monorail already in place started to take shape.

“This is a privately funded, non-profit system and the first one of its type and the first one that we hope can fully pay for itself. Buses and other public transit systems tend to be subsidized by as much as 60 percent,” he says.

The four-mile mass-transit project is the first of three phases. The second phase will add monorail service from the Sahara Hotel to downtown Las Vegas; the third phase will connect the airport with the southernmost point of the monorail at the MGM Grand.

“Although the first phase is totally funded by private sources, the second and third phases will take advantage of federal transportation funds and revenue bonds,” Walker says.

In the first phase, many parties have a financial stake. In addition to the conventional investors, hotels along the route were required to commit $5 million of unsecured debt to the project and grant right-of-way for the line. They also must pay for the walkway or bridge that connects the hotel to the monorail station.

Contractors on the job also have a financial stake. Bombardier, the company building the monorail cars and support equipment to operate the driverless trains, brings $15 million in unsecured debt to the project; the general contractor, Granite Construction, carries $3.5 million in unsecured debt.

“This is a 40-month, design-build project. If the monorail opens sooner, Bombardier and Granite Construction get a portion of the sales between when it opens and the scheduled open date; if they don’t open on time, they will be assessed 1.1 times the debt service cost until it opens. We are definitely on schedule,” Walker says.

More about the monorail
The Bombardier Mark VI monorail cars are an advanced design with roots in the monorail system used at Disney World.

“The monorail style was chosen because it is a dynamic, sexy-looking style that operates quietly, which is important because the units travel very closely to hotel rooms,” says Todd Walker of the Las Vegas Monorail system.

The driverless four-vehicle cars can carry 225 persons, but planning for growth, the stations and guideways are designed to handle up to eight-car units. The units are powered by a 750-volt DC system and have a top speed of 50 mph. Five traction stations, which are transformer stations placed along the line, transform 12.5 KVA to 750 volt DC power. All stations and trains are controlled by two operators on duty in the Operations, Maintenance and Storage Facility (OMSF) which sits at the end of the line near the convention center.

“The traction station in the OMSF was built on-site, but the other traction stations were prefabricated at the Bombardier plant, then shipped in two pieces to the job,” says Reg Brockway, Bombardier’s testing and commissioning manager for the project.

“The prefabricated units are great because they are fully factory-tested. All we need to do is make a connection that completes 200 connections we would have to otherwise do by hand,” he says. Each traction station is also set up for fast connection to a portable gen set if the system ever loses utility power. Further, the stations offer redundancy to one another along the line.

Prefabricated traction houses are factory tested, then moved on site. Connection is simple: One connection joins more than 200 circuits.

The system will run from 6 a.m to 2 a.m., with four hours for system maintenance. Under a series of contracts that spans 15 years, Bombardier will handle maintenance and operation of the facility.

Published in the May/June 2003 issue of Contractor Tools and Supplies magazine.

The first large-scale, privately funded mass-transit system in the country is under construction in Las Vegas