by Robert Johnson
Work started in the Fall of 2019 on an underground Group Rapid Transit system to serve the sprawling Las Vegas Convention Center (LVCC). The project is currently nearing completion. It has had unusually high public visibility because the system concept was developed by Elon Musk, one of the richest people in the world, and well known for his Tesla and SpaceX ventures. Musk has kept his 38 million Twitter followers informed of the progress of the Las Vegas system, as well as other proposed applications of his underground transportation technology.
While the infrastructure of the LVCC system in now (quite literally) set in concrete, the characteristics of the vehicles are still not clear. They have been shown in renderings as a mix of Tesla Model 3 sedans and larger 12-16 passenger van-like vehicles. The sedans seem unsuitable because of their low capacity relative to expected demand, slow boarding because of a low roofline, and lack of wheelchair access. In a setting such as the LVCC they might be offered as an option during periods of low demand.
In addition to the LVCC project, Musk’s tunneling company, The Boring Company (TBC), has proposed a more extensive system to serve Las Vegas from McCarran airport to the CBD. It would consist of tunnels running west from Terminal 3 of the airport and then north along Las Vegas Blvd (the “Strip”). Several dozen hotels and casinos along the Strip would be served by short spur tunnels. A longer spur would serve the new 65,000 seat Allegiant stadium.
The LVCC system is officially called the “Campus Wide People Mover”, while the TBC refers to it as the LVCC Loop. The term “Group Rapid Transit” is not used. However the LVCC system and the proposed system along the Strip seem to meet the definition of GRT that has been in use for many decades. In particular, all trips would be non-stop origin-to-destination, with intermediate stations bypassed.
The LVCC system is scheduled to be complete by the end of 2020. It should be of great interest to anyone working with GRT or Personal Rapid Transit (PRT).
THE LAS VEGAS CONVENTION CENTER SYSTEM
The LVCC system consists of parallel twin tunnels 0.85 miles (1.37 km) long, one for each direction of travel. There are three stations. At each end there is a surface station connected by ramps to the ends of the tunnels. The third station is located underground, about halfway between the two ends. Tunneling for the system was completed in May 2020. It was done with technology that was fundamentally conventional, specifically a Lovat Tunnel Boring Machine with a cutter head 14 feet (4.3 m) in diameter. The tops of the tunnels are about 30 feet (9 m) below grade.
TBC is currently proposing that all vehicles be battery powered and steer themselves along a flat surface without lateral constraint. This approach was pioneered by 2getthere with the ParkShuttle in the Netherlands. It is different from a system TBC demonstrated in December 2018 which had guide wheels similar to those used on curb guided buses.
The tunnels have a circular concrete lining with an inside diameter of 12 feet (3.7 m). Once the circular tunnel is finished, gravel and asphalt are added to its floor to a depth of approximately three feet (90 cm) in the middle. The final result is a flat driving surface about ten feet (3 m) wide.
The design capacity of the system is 4400 passengers per hour. This is apparently total boardings at all three stations rather than pphpd. The maximum speed is 35 mph (56 kph), and TBC has stated that vehicles will be spaced about 500-600 feet (150-180 m) apart when away from stations, suggesting a headway of about 10 seconds.
The ramps leading up to the surface stations are steep, and the lanes within the stations require the vehicles to have a tight turning radius. This gives a very compact layout. Based on drawings and renderings of the underground central station, it has mainline bypass lanes and sawtooth vehicle berths, but no acceleration/deceleration lanes (although it is difficult to be certain). The use of online accel/decel cuts mainline capacity but greatly simplifies station design.
TUNNELS VS. ELEVATED GUIDEWAYS
Major cost savings are possible if stations are placed at grade rather than below or above. Elevators and escalators can be omitted, and vehicle berths and passenger waiting areas are perhaps an order of magnitude cheaper. The difficulty is bringing vehicles up/down to grade from the mainline guideway.
The running surface of the LVCC tunnels is approximately 40 feet (12 m) below grade. This results in about twice the vertical distance to reach grade compared with vehicles coming down from an elevated guideway. However as the LVCC system shows, most of a ramp coming up from below can be covered over and is thus invisible. In contrast, the ramp of an elevated system coming to grade is a visual and physical intrusion along its full length.
Another consideration is that gravity will help decelerate vehicles arriving at a surface station from below, while it accelerates vehicles departing on a down ramp. This is the opposite of the situation with an elevated system.
The LVCC system may very well demonstrate that tunnels can be a cost-effective alternative to elevated guideways, particularly if most stations are at grade. Its location at an important Las Vegas attraction might help popularize this technology.
