The construction phase of the Frankfurt Bridges is divided into eight construction phases and should be extremely efficient, as the planning was not only very detailed in advance, but was also binding for the citizens

The most important goal is not to burden the city with mega construction sites or permanent construction sites. Due to the planned financing structure, the Frankfurt Bridges are not subject to the European tendering obligation, which reduces the enormous effort involved, increases the awarding of small-volume contract components to local craftsmen and regional medium-sized companies and yet involves all countries in the European cultural area, as Europe-wide sourcing is an integral part of both the declaration of objectives and purpose of the planning company gGmbH and the construction company gGmbH. In addition, BIM construction can be realised smoothly and extremely efficiently thanks to the extremely detailed planning.

Starting construction with the ring road makes the most sense from an infrastructural point of view - but also presents the greatest challenges

If the development plan for the ring road is only adopted after the development plans for the "arms", then it is also possible to simply start opportunistically with the arm where there is the least resistance and the fewest technical challenges.

Implementation should be easiest for development plan 4 towards Kennedyallee, as comparatively few residents are affected and only S-Bahn bridges need to be bridged

While the Ring and especially its inner arms run relatively close to the houses on the right and left (with a clear distance of only 7 metres in some cases), there are mostly office buildings along Kennedyallee - and the residential buildings in this section are at least 10 to 15 metres away from the Frankfurt Bridges, so that they are an enrichment without being a nuisance - provided they are green and attractive in terms of craftsmanship. Resistance from neighbouring residents is likely to be correspondingly less than, for example, on the Ring. Only the construction site on the "doorstep" could turn residents and, above all, offices into opponents of the construction of the Frankfurt Bridges. The most important technical challenge can be mastered with this bridge arm as an example: The Frankfurt Bridges, which usually run with a clearance height of around 5 metres above the ground, have to reach a clearance height of up to 11 metres for their course over S-Bahn bridges (and further on towards the airport over motorway bridges) - consequently, the incline has to be started more than 100 metres in advance. In order to fulfil the special objectives of the Frankfurt Bridge Vision, the elevated areas of the Frankfurt Bridges were to be built on classic masonry columns, which can be aesthetically designed in an artistic manner and at the same time represent a sustainable construction method without concrete using regionally available stone - beautiful for the residents, durable for eternity and an exemplary model for other buildings.

The construction sites of the Frankfurt Bridges must be provided with the highest level of protection for residents

A comprehensive noise protection concept is drawn up as early as the planning phase: Mobile noise barriers, the selection of low-noise construction methods and equipment or even night-time construction sites with a maximum noise level of 40db are fundamental components of bridge construction. In addition to the usual information for residents, there is a project website with regular information about the construction progress and, if necessary, opportunities for residents to visit the construction site.

Dust protection walls on scaffolding also shield residents, while elements with translucent sections help to prevent residents' windows from being darkened during construction.

As a showcase for European innovation, the Frankfurt Bridges are intended to represent Europe's Silicone Valley - and at the same time represent an economic stimulus programme for local and regional trades and SMEs

The Frankfurt Bridges are an infrastructure project, the scale of which is in any case so large that with an ambitious planning and construction period totalling 15 years according to HOAI, it would not be possible to deliver from just one country anyway.

The thousands of metres of running wrought-iron railings alone would keep metalworkers all over Germany busy or block their capacity for a long time, and there would still not be enough tradesmen for this size of order - to name just one example. The same applies to the planting of very specific plants both on and along the bridges and in Frankfurt in accordance with the unsealing plan: All the tree nurseries in Germany would not be sufficient to grow and supply this volume of orders; here too, it is inevitable that we will have to turn to neighbouring European countries. These illustrative examples are essentially no different to the larger trades such as the TGA infrastructure, the geothermal infrastructure or the software infrastructure in the supply centres of the bridges - to name just a few trades.

Added to this is the cooperation with research and science, which not only runs through the entire planning phase, but also the operating phase: Here it is necessary to work on the city of the future not only with German universities and research institutes, but also with those from other European countries. Only if this scientific interaction is ensured from the outset can the Frankfurt Bridges act as a showcase for innovations that can be disseminated throughout Europe (and ultimately the world). And if photovoltaic concepts are developed jointly with Mediterranean institutes, geothermal concepts are explored in greater depth with Swiss institutes or extensive and intensive green roof concepts are developed with institutes from Scandinavia or the Netherlands, then it is also efficient to give the companies that may even have worked on them the opportunity to fulfil orders.

At the latest when it comes to the arts and crafts, it becomes necessary to involve various different countries, as France had to learn the hard way during the reconstruction of the destroyed Notre Dame areas: for the production of vintage wooden railways, one has to rely on masters from Portugal and Romania, for wall and ceiling paintings of this scale on masters from Italy, for stonemasonry of this complexity on masters from Poland, etc., etc.: All European countries are needed.

All construction activities for the construction of the Frankfurt Bridges must be planned not only spatially, but also in terms of time: In the BIM process, time windows and milestones are assigned to the overall geometric 3D model of the structure

4D-BIM (Building Information Modelling) is the name given to the process that creates an intelligent link between the digital 3D model (which defines the geometry of the building) and the information on the execution time of the various activities required to realise the building. The result is a real simulation of the construction phases of the building or its elements. If a BIM platform and BIM managers are already used in the planning phase in accordance with HOAI to ensure that all elements of the construction project are dovetailed, a fifth dimension can be added during the tendering phase, which benefits the efficiency of the construction phase: the costs.

To ensure that there are no eternal construction sites during the construction of the Frankfurt Bridges, the BIM approach for the construction project must also be mapped organisationally

BIM managers are not only assigned to the individual divisions of Baugesellschaft gGmbH as staff units, but are also integrated into all management functions during the construction phase: Even if the work of the planning company gGmbH has already been carried out in a matrix with BIM managers and includes time and costs as well as 3D modelling, it must still be ensured during the construction phase that the results of this planning in five dimensions are also the reference point for all processes during construction. The actual construction work is carried out section by section across the 6 construction manager areas and 2 control areas - and this interlinking is ensured by the BIM managers and the BIM IT platform.

The BIM approach guarantees the highest possible efficiency - which plays an important role in the construction of Frankfurt's bridges, not only in terms of keeping costs down, but above all in

avoiding unnecessarily long periods of "eternal construction sites" for Frankfurt's citizens

Like other infrastructure projects in Germany, the construction of the Frankfurt Bridges must not become an eternal construction site such as "Stuttgart 21": Construction work for this began in February 2010 and commissioning was planned for December 2019. In the meantime, commissioning has been postponed to December 2026 - a construction delay of 9 years to 16 years. It was a similar story with the costs of the project: while the cost planning in the early 2000s originally envisaged 2.5 billion euros, in 2006 the amount was estimated by Deutsche Bahn at 2.8 billion euros, in 2008 at 3.1 billion, in 2009 at 4.5 billion and in 2013 at 6.5 billion euros. Forecasts are now at €11.5bn by 2026, mainly due to delays caused by a lack of depth and dovetailing in the planning process as well as a lack of coordination between contractors and construction activities. In the case of the Frankfurt Bridges, these causes can be ruled out from the outset thanks to BIM processes during planning and construction.

The non-profit form of the construction company guarantees not only construction site management that is orientated towards the interests of the citizens,

but also a procurement policy that focuses on the promotion of skilled trades and the integration of the first graduates of the new Master Crafts Academy

Like its predecessor planning companies, the construction company for the construction of the Frankfurt Bridges is organised as a non-profit limited company. On the one hand, this ensures that the construction sites are equipped or managed with the highest degree of resident protection; on the other hand, it ensures that priority is not given to the cheapest providers when awarding contracts, but to those who (1) are commissioned in the most sensible way from a sustainability perspective or who (2) should be given preference with regard to training and promoting young talent or who (3) cooperate with science and research, etc. etc.

The question of which regions the contractors should come from is also relevant for the fulfilment of the non-profit objectives of Baugesellschaft gGmbH: The Frankfurt Bridges are to become Europe's Silicon Valley, and accordingly companies from the European cultural area (i.e. not limited to EU members) are given priority. I

In addition, not only large corporations should be commissioned for such a large infrastructure project, but also medium-sized and smaller companies should be given a chance: For the construction of the Frankfurt Bridges, there are trades that can only be fulfilled by a few large European companies, such as the construction of geothermal plants or the delivery of large reinforced concrete elements. However, the situation is different for smaller trades that require huge quantities, such as masonry, stonemasonry or wrought iron railings. Here, the intention is to award contracts to medium-sized and smaller companies that fulfil special quality criteria, such as those listed above, e.g. that they are training companies or that a particularly difficult traditional craft is still mastered.

As the construction industry throughout Europe is already suffering from a shortage of young talent, it is essential that the next generation of tradespeople be massively promoted by the state in the ten years before construction work begins and that the "Master Craftsmen's Academy", which is to reach its full size on the Frankfurt Bridges, be set up in temporary premises years before construction work begins and start training tradespeople from all trades.

The construction organisation of the Frankfurt Bridges builds on the BIM planning and BIM organisation of the planning phase with BIM coordination

The construction of the Frankfurt Bridges is taking place along the development plans with construction sites that are putting a strain on important access roads in Frankfurt and the ring road.

It therefore makes sense to build the motorway in sections, starting either with the ring road or the southern arm of Kennedyallee. The extensive planning phase of around 10 years in total (4-5 years concept planning, 5-6 years planning according to HOAI) and the BIM platform of 5D planning ensure that the construction project is carried out extremely efficiently and with the least possible impact on citizens.

The corporate form of the gGmbH construction company, like the non-profit planning companies before it, ensures that the implementation of the Frankfurt Bridges, as promised in detail to the citizens and approved, is realised without any delaying burden. At the same time, the objectives set out in the social contract guarantee, among other things, a procurement policy focussed on education, innovation and Europe's cultural heritage.