GLMZ's vertical dimension is as consequential as its horizontal spread, and the infrastructure that moves people between the city's stacked levels — elevated corporate plazas, mid-tier residential decks, ground-level commercial corridors, and sub-street industrial and residential warrens — constitutes a distinct and deeply stratified transit category. The city has approximately 14,000 registered vertical transit shafts, ranging from single-cab residential lifts in mid-tier towers to the massive multi-shaft transit columns called Verticals that serve as connective tissue between the city's horizontal transit layers. Of these, roughly 3,200 are classified as public-access infrastructure; the remainder are private, corporate, or restricted.

The eleven major public Verticals are each managed by a different concessionaire under the Meridian Infrastructure Compact, a governance arrangement that produces chronic interoperability problems. A commuter descending from the elevated Harmon Corporate Plateau at Level 7 to the ground-level Portsmith transit concourse must navigate a transfer from a Harmon-operated internal shuttle to a Caldor Transit Consortium public Vertical, with separate fare systems, biometric authentication handoffs, and — critically — a citizenship grade verification that can result in rerouting or denial at the transition point. Workers with Tier-Three status who are employed in Tier-One-zoned elevated districts face this friction twice daily, adding an average of 22 minutes to each commute leg according to 2172 transit studies.

Below the ground level, the Vertical network becomes significantly more fragmented. The sub-street warrens — home to an estimated 600,000 residents, predominantly Tier-Four and unregistered — are served by a combination of aging municipal lift shafts, many dating to the city's pre-corporate infrastructure era, and informal vertical transit operations. Informal operators, called shaft runners locally, maintain cable-and-counterweight lifts in disused maintenance shafts, charging per-trip flat fees in non-traceable value tokens. These operations are technically illegal under Meridian Infrastructure Code but are tolerated because the alternative — complete vertical immobility for sub-street populations — would generate obvious pressure on surface-level infrastructure. MSA periodically raids the more visible shaft runner operations, typically in conjunction with sweeps targeting other informal economy activity in the warrens.

The vertical transit gap has direct implications for employment, healthcare access, and emergency egress. Sub-street residents seeking medical care at the nearest mid-tier clinic face a vertical transit cost that represents, for many, a meaningful economic threshold. Emergency egress planning for sub-street zones formally assumes residents will use stairwells rather than vertical transit in crisis scenarios — an assumption that infrastructure engineers privately acknowledge as unrealistic given the physical scale of some warren districts. The 2169 Tunnel Six fire, in which 34 sub-street residents died in part because functional emergency stairwells required transiting through a locked corporate maintenance zone, generated a brief public discussion of vertical transit equity that produced no substantive policy change.