Urban-structure interventions form the first and most important group of the compact-city concept. They are not about a single grand gesture, but about a system of mutually reinforcing, finely dosed steps — that is, about where and how District 18 should densify while preserving its character.

1. Optimising building intensity

The starting point is a sober realisation. The area of District 18 is 38.6 km², roughly nine times the inner city inside Pest's Grand Boulevard (Nagykörút), so densifying the entire area is neither realistic nor desired. The question, then, is not by how much the district should become denser, but where.

• Encouraging TOD-type developments. More intensive neighbourhood investments take place around higher-capacity transport hubs (transit-oriented development), so that public transport, by its proximity, offers a competitive alternative to the private car. In Pestszentlőrinc-Pestszentimre, suitable stops include Pestszentimre, Kispest and Pestszentlőrinc, and Szarvas csárda tér can also be drawn in. The aim is not metropolitan-scale development around every stop, but a medium-intensity, mixed-use, easily walkable hub zone.
• Densifying hubs and building a system of centres. By arranging the identified service clusters and transport hubs into a hierarchy, a polycentric system of centres can be built. The already busier, more function-rich stretches of Üllői út can be reinforced as primary centres, the central areas of the housing estates and of Pestszentimre as local sub-centres, while areas lacking sub-centres can be organised around new centres. The essence is clarifying the roles and connecting the hubs in a networked yet hierarchical relationship.
• Encouraging densification along the main roads. If densification appears in the wrong place, it provokes residents' antipathy and breaks the district's character; the proposal therefore directs densification along the main axes. Üllői út, Nagykőrösi út, Gyömrői út and the Méta utca corridor are the most suitable receiving areas — here the transport links are strongest and visibility is greatest, while in many places the built environment is currently of low intensity. Densification along the axes simultaneously strengthens the urban axes and protects the residential areas behind them.
• Encouraging lot consolidation (terraced-house developments). A transitional zone between the urban axes and the single-family-house areas. The terraced house provides a higher intensity than suburban development, but breaks the district's character less than scattered over-building with apartment blocks, and it is not unknown in the district either.
• Encouraging housing above retail units. Applicable where commercial presence is strong but residential density is low. New homes are created without the city expanding further. As an international example, in Los Angeles an apartment building of more than 800 units is planned on top of a Costco store. In the district, the Lőrinc Center and the SPAR store at Szarvas csárda tér could be drawn into a similar development.

2. Activating underused areas

Making the district more compact cannot be based on further greenfield expansion; the reserves must be sought inwards. Today these occupy considerable space but produce little urban value. The hub developments are also linked to this aim, since around the stops it is often precisely these areas that provide the receiving space.

• Reactivating brownfield sites. The tool with the greatest structural weight, since such reserve areas make up about 4.5% of the district's territory. From a compact-city perspective, the direction is not monofunctional, logistics-oriented reuse, but a reactivation that connects to the urban fabric, has a more mixed character and can be developed in several phases — potentially even as a sustainability test site. Such potential is offered, for example, by the former Lőrinci Fonó or the Lőrinci Hengermű site.
• Building on car parks and underused plots. Around service and transport hubs, surface car parks and oversized, poorly used plots are common. This is not about the immediate elimination of parking, but about a shift in land-use thinking — namely, that in the best-positioned locations surface parking gradually gives way to more value-creating, more urban development.
• Activating vacant infill plots. The most fabric-like intervention. It does not create a new centre, but makes the existing structure denser, more continuous and more usable. It is especially valuable in areas already served by utilities and services, and can host not only housing but also smaller service and community functions. Along Üllői út, the development of several such plots has already begun.