In general relativity, an event horizon is a boundary in space-time beyond which events cannot affect an outside observer – the point of no return at which gravitational pull becomes so great as to make escape impossible.1

Introduction

Event Horizon is a set of propositions for the linear corridor Sava makes in the fabric of Zagreb, developed through four sites spaced along its course. The apparent question being what do they share with one another, but also what is gained by their distinction? What does taming of the river entail and should it be tamed in the first place? Ultimately, how can Zagreb develop its own unique riverscape, not by chasing after existing European models, but by carefully crafted ‘urban-active’ pockets of events?

Zagreb, at its best, is the city woven around such urban active points. The longevity of a chain of public squares ‘Lenuci horseshoe’, comes not as an adaptation of the Viennese ring, but through the understanding of the local condition – the permanence of the ‘temporary’. Planner Milan Lenuci purposefully employed urban placeholders, events such as tennis courts and ice-skating rinks as nodes of activity to generate buzz and ultimately investment. These are the circumstances and the tradition in which urban active architecture can be discussed. As preferred notion to public participation it stands better chance of someone assuming responsibility. Project relies on ‘soft’ program to complement the site, often by amplify the existing one. Sites work together to reinforce each other as a kind of urban testing ground trying to ask the right questions, rather then eagerly provide answers.

Manifesto

Zagreb Sava river corridor as:

a) a system b) destination c) motion d) density e) behaviour f) heritage g) icon

Archetypes facilitate physical responses. They can be charged with function or they can be freed from it. Suspended between sign and material object events are hatched out of behaviour. Circle2, line3, field4 and point5 are put in place, an archetype per site to reframe the memory and examine the potential of the four sites through specific scenarios: relocation, framing, planting, orienting.

River corridor Execution and maintenance of a corridor along Sava banks with a new cyclist lane spanning the width of Zagreb, (over 20 km one way) which would allow for a significant boost in recreational infrastructure. By increasing in the speed of travel, we can shorten distances and achieve densification of events.

Turning points Execution and maintenance of ramps and platforms that use existing bridges for primary structure. They allow cyclists a smooth crossing of the river.

Existing Identity Makers By pinpointing specific identity places along Sava, new urban equipment would be put in place (gardens, platforms, benches, small bridges) to promote its inherent, but still unused potential.

New Identity Makers Simple rules are devised to govern planting of trees and mowing of grass. The flooding area between the river and the sandbar can easily host a range of events, which are mowed into being.

Re:thinking public sculpture Sava corridor drops the idea of conventional sculpture in favor of spatially active one. This principle generates stronger genius loci through a stronger spatial interaction.

Circle

Program relocation

+ Site proposes the relocation of the Zagreb hippodrome. A recently missing program gives ample contributing to the urban rethinking of the central South Zagreb’s neighborhood Kajzerica and by an extent also Zagreb fair breaking the long standing status quo. Morphologically the structure encircles the perimeter of the site, creating an inside condition, a horseback ridding park. Adjacent to Sava sandbar it allows for the sport to utilize the south riverbank as a valuable addition to the unique identity of Zagreb’s riverscape.

Line

Urban frames

+ A series of linear structures turn the central of the four sites into a sequence of open-air rooms. They inject urban form and identity to the site as each ‘room’ can now be independently considered. They are pedestrian connectors as well as amplifiers of the existing adjacent program. The main structure is positioned at the west edge of the site where it st¬ands as a ‘place holder’ for a future bridge, which would one day be an axial extension of the University Strip and a connection to the Kajzerica neighborhood and Zagreb fair.

Field

A ‘green nudge’

+ Urban farming, the existing condition of the site is being integrated into an agricultural park. Irrigation system, a green house and a pedestrian walkway make up for the essential infrastructure. The green house is cross-programmed with a restaurant and a marketplace as contemporary ‘green’ brand, which grows, sells and prepares seasonal menu, harvested on site. The system could be copied in other parts of the city with a similar urban condition promoting the worth of urban gardening. In the case of Savica it becomes a focus of the neighborhood.

Tower

An affordable icon

+ A watchtower protects the most remote and abstract location of the four. Agricultural fields, a water treatment plant and the eastern most fragments of Zagreb sprawl are its borders. As a tower it possesses two important properties; as a marker it reinforces the argumentation of recreational activities along the Sava by providing a destination and it allows a panorama view – the ultimate promise of a tower. Constructed from steel trusses and braced by cables, it stands erect en route to the Zagreb airport. The polygonal cable mesh construction serves as a façade of the tower, but it also occupies and protects the site. At night the cables are lit making way for an idea of an affordable icon, as a part of the public sphere.

1. Wikipedia

2. relocating the hippodrome program breaking the ‘urban status quo’

3. framing ‘urban rooms’, for space to become place

4. planted, it provides a green focus of the Savica neighborhood

5. an orientation and a destination for the Sava recreational corridor