Vertical Transportation Systems

Vertical Transportation Systems

Moving people through The Mukaab requires rethinking vertical transportation from first principles. The building’s cube geometry, mixed-use program, and projected traffic loads create demands that exceed the capacity of any existing elevator system by an order of magnitude. The solution requires a multi-modal transportation network combining high-speed elevators, horizontal transit systems, autonomous electric vehicles, and the continuous circulation path provided by the spiral tower.

Scale of the Challenge

The Mukaab must accommodate its permanent residential population, hotel guests, commercial tenants, and the share of 90 million projected annual visitors to the New Murabba development who enter the building itself. Even conservative estimates suggest daily movement counts in the hundreds of thousands — people traveling between residential floors and retail zones, between hotel rooms and entertainment venues, between office spaces and restaurants.

Conventional elevator systems in supertall buildings manage these flows through sky lobbies and express zones. The Burj Khalifa’s 57 elevators serve 163 floors in a building with approximately 12,000 daily occupants. The Mukaab’s occupant load could be 10 to 20 times larger, distributed across a volume rather than a linear tower, requiring a fundamentally different approach.

Three-Dimensional Movement

The critical difference between the Mukaab and conventional supertall buildings is that movement within the cube occurs in three dimensions, not just vertically. A resident living on the 60th floor who wishes to visit a restaurant at the same level but on the opposite side of the building must traverse 400 meters horizontally — equivalent to a four-block walk in a typical city grid. This horizontal distance creates demand for horizontal transit systems that have no precedent in building design.

The planned integration of autonomous electric vehicles within the building addresses this horizontal movement challenge. These vehicles, operating on dedicated routes within the structural framework, provide point-to-point transportation across the building’s horizontal dimension. Integration with the vertical elevator system creates a network where passengers can transfer between horizontal and vertical modes at intermediate hubs.

Emergency Evacuation

The evacuation implications of the Mukaab’s transportation requirements are addressed in our fire safety analysis. In summary, evacuating a structure with the Mukaab’s occupant load requires protected evacuation routes, refuge areas at intermediate levels, and communication systems that coordinate evacuation across the building’s multiple zones. The transportation system must transition rapidly from normal operations to evacuation mode, potentially reversing elevator travel directions and activating emergency vehicle routes.

High-Speed Elevator Technology

The elevator systems within the Mukaab must transport occupants across 400 meters of vertical travel at speeds sufficient to prevent unacceptable wait times. Current state-of-the-art high-speed elevators — including the units in Shanghai Tower operating at 20.5 meters per second and the Burj Khalifa’s elevators at 10 meters per second — provide benchmarks for the technology required. At 18-20 meters per second, a non-stop express elevator traverses the Mukaab’s full height in approximately 20-22 seconds, comparable to the express elevator experience in the world’s tallest towers despite the Mukaab’s shorter absolute height.

The elevator count required for the Mukaab’s occupant loads represents an order of magnitude beyond any existing building. Where the Burj Khalifa operates 57 elevators for approximately 12,000 daily occupants, the Mukaab’s projected population demands an estimated 200-300 elevator units organized in zones — local elevators serving clusters of 10-15 floors, express elevators connecting sky lobbies at quarter-height intervals, and shuttle elevators providing direct access between ground-level transit connections and major destination floors. The shaft space consumed by this elevator infrastructure represents a significant fraction of the building’s total floor area, creating tension between transportation capacity and usable commercial space that the design team must optimize.

Double-deck elevators, which carry passengers on two levels simultaneously and serve alternating odd/even floor pairs, offer a 25-30 percent increase in handling capacity within the same shaft footprint. Triple-deck configurations, though not yet deployed in commercial buildings, are under development by major elevator manufacturers and could provide further densification of vertical transportation capacity within the Mukaab’s shaft allocations.

Sky Lobby and Transfer System

The sky lobby concept — intermediate transfer floors where passengers switch between express and local elevators — is essential for managing the Mukaab’s vertical traffic. Positioned at approximately 100-meter intervals (floors 25, 50, and 75 in a 100-floor configuration), these sky lobbies function as internal transit hubs where passengers arriving by express elevator disperse to local elevators, horizontal transit systems, or autonomous vehicle routes serving their destination zones.

Each sky lobby must accommodate the simultaneous arrival and dispersal of hundreds of passengers without congestion. The architectural design of these spaces — incorporating wide circulation corridors, clear wayfinding signage in Arabic and English, and retail or hospitality amenities that serve waiting passengers — transforms what could be a bottleneck into a destination experience consistent with the building’s premium positioning within the New Murabba development.

Autonomous Vehicle Integration

The integration of autonomous electric vehicles within the Mukaab addresses the horizontal movement challenge that distinguishes this building from conventional supertall towers. A resident on the 60th floor traveling to a restaurant at the same level but 400 meters distant — the full width of the cube — faces a journey equivalent to four city blocks. Autonomous vehicles operating on dedicated guideways within the mega-frame structural system reduce this horizontal transit time to 2-3 minutes, maintaining the connectivity expected in a vertically integrated city.

The vehicle fleet size, routing algorithms, and charging infrastructure represent a transit planning exercise comparable to a small city’s public transportation system. The AI-enabled smart building systems optimize vehicle dispatch based on real-time demand patterns — surging capacity toward residential zones during morning commute hours, redirecting toward entertainment and dining zones in evenings, and pre-positioning vehicles at sky lobbies before express elevator arrivals to minimize passenger wait times. The 64-million-cubic-meter enclosed volume provides controlled operating conditions — no weather variability, consistent surface conditions, and predictable traffic patterns — that simplify the autonomous driving challenge compared to outdoor urban environments and enable higher operating speeds and tighter vehicle spacing than public road autonomous vehicle deployments.

The total transportation system — elevators, autonomous vehicles, horizontal people movers, and the spiral tower circulation path — must be designed as an integrated network where transfers between modes are seamless and total journey times between any two points in the building remain under 10-15 minutes. Achieving this performance target within a 400-meter cube containing 2 million square meters of floor area requires transportation engineering that draws on urban transit planning, airport terminal design, and theme park crowd management — disciplines not traditionally associated with building engineering but essential for a structure that functions as a vertical city housing, employing, and entertaining populations comparable to a mid-sized town.

Elevator Engineering in Desert Conditions

The Mukaab’s elevator systems must contend with environmental conditions that compound the engineering challenge beyond conventional supertall installations. Riyadh’s summer temperatures exceeding 50 degrees Celsius heat elevator shafts and machine rooms to levels that stress motor windings, electronic controls, and rope lubricants. The thermal expansion of 240 millimeters across the building’s 400-meter dimensions causes guide rail alignment shifts that must be compensated in real time — a challenge addressed through floating guide rail supports and continuous alignment monitoring systems that adjust rail positions to maintain the millimeter-precision tolerances required for safe high-speed operation.

The elevator rope systems themselves present scale challenges without precedent. Conventional steel wire ropes for a 400-meter travel height weigh approximately 20-25 kilograms per meter, meaning the rope weight alone for a single elevator shaft approaches 10 tonnes — a parasitic load that the hoisting machine must overcome in addition to the car and passenger weight. Carbon fiber composite ropes, pioneered by KONE and Otis for ultra-tall installations, reduce rope weight by 80-90 percent while maintaining equivalent tensile strength, making them essential technology for the Mukaab’s express elevator shafts.

The electrical power demand for 200-300 elevator units operating simultaneously represents a significant fraction of the building’s total electrical load. Regenerative drives — systems that recover energy when elevators descend with heavy loads or ascend with light loads — can reduce net elevator energy consumption by 25-40 percent, feeding recovered energy back into the building’s electrical grid. At the Mukaab’s scale, this recovered energy amounts to megawatts of capacity that reduces the burden on the building’s primary power supply and contributes to net-zero energy aspirations.

Traffic Simulation and Demand Management

The AtkinsRealis transportation engineering team employs multi-agent simulation software to model the movement patterns of hundreds of thousands of daily occupants through the Mukaab’s three-dimensional transportation network. These simulations — which track individual virtual passengers from origin to destination, recording wait times, travel times, transfer penalties, and crowding levels — validate that the proposed elevator count, autonomous vehicle fleet size, and sky lobby configurations deliver acceptable service levels during both normal operations and peak demand scenarios such as Friday prayers, major entertainment events in the holographic dome, or emergency evacuation triggered by the fire safety systems.

The AI-enabled building management system uses real-time occupancy data from turnstiles, access cards, and anonymized mobile device signals to predict transportation demand 15-30 minutes in advance and pre-position elevator cars and autonomous vehicles accordingly. This predictive dispatch system — analogous to ride-hailing surge management but operating within a controlled building environment — reduces average passenger wait times by 30-50 percent compared to conventional call-response elevator dispatching. For the Mukaab’s 1 million tonnes of structural steel framework supporting this infrastructure, the vibration isolation of elevator machinery at 200-300 locations throughout the mega-frame requires careful acoustic and vibration engineering to prevent motor-induced oscillations from propagating through the structure to occupied spaces. The $50 billion project budget accommodates the premium elevator technology, autonomous vehicle systems, and AI dispatch infrastructure required to make three-dimensional movement through the world’s largest building feel effortless.

Maintenance and Lifecycle Engineering

The operational lifetime of the Mukaab’s transportation systems demands lifecycle engineering that plans for component replacement, technology upgrades, and fleet expansion across decades of continuous service. Elevator cars, drive motors, control systems, and safety equipment have design lifespans of 20-25 years before requiring major overhaul or replacement. For 200-300 elevator units, this means 8-12 major elevator modernization projects running continuously throughout the building’s operational life — a perpetual renovation program managed by a dedicated vertical transportation engineering team.

The autonomous vehicle fleet introduces lifecycle considerations unfamiliar to building engineering — battery degradation, software obsolescence, and sensor calibration drift that require vehicle replacement or major refurbishment on 5-8 year cycles. The guideway infrastructure embedded within the structural framework must accommodate successive generations of vehicle technology without structural modification, requiring interface standards and dimensional tolerances that anticipate technological evolution.

The foundation system of 1,200 piles carries not only the static weight of the transportation infrastructure but the dynamic loads from hundreds of elevator starts and stops per hour and autonomous vehicles accelerating and braking across the building’s horizontal guideways. These repeated dynamic loads — small individually but numbering in the millions annually — must be accounted for in the fatigue analysis of structural connections supporting elevator machinery and vehicle guideways. The AtkinsRealis structural engineering team has modeled these vibration-induced fatigue loads across the building’s full 100-year design life to ensure that no transportation-related structural component requires intervention beyond routine maintenance — a critical performance requirement for systems buried deep within the 64-million-cubic-meter enclosed volume where access for structural repair would be extraordinarily disruptive to building operations.

Accessibility and Universal Design

The Mukaab’s transportation system must provide universal access for occupants of all mobility levels — wheelchair users, parents with strollers, elderly visitors with walking aids, and people with visual or cognitive impairments. Every elevator car, autonomous vehicle, and horizontal people mover must comply with Saudi accessibility standards and international best practices for inclusive design. Tactile floor indicators, audible announcements in Arabic and English, Braille signage at every call station, and wheelchair-accessible vehicle interiors ensure that the building’s three-dimensional transportation network serves its full occupant population without discrimination. The fire safety evacuation systems include designated evacuation elevators and refuge areas sized for wheelchair users, ensuring that mobility-impaired occupants are not disadvantaged during emergency egress from the 400-meter structure.

For broader context, see five engineering imperatives, interior architecture, and smart building systems.