Civil engineering Management & Consultancy




The building of a road is preceded by a complete design and calculation process. The road has to be designed in both spatial and construction terms. InVra plus has the knowledge and software needed to do both. <[p>We put the design guidelines into practice for the design aspect of the work. Designing in Autocad Civil 3D makes it possible to quickly and clearly present the designs.


We produce the road designs in various stages from outline design to detailed design for public or private clients up to implementation design for contractors.

Anticipated climate change is making it more and more important to put good water management in place. One expected change is that rain showers will become shorter and heavier: more water in less time. Drier periods are also expected to last longer. Rainwater drainage will need to be prepared to prevent flooding or water shortages. This underlines the importance of well-designed sewer systems in urban areas. Invraplus BV can help you with this.


A good design is always based on a calculation. Before making the calculation consultations are held with the client to identify the rainfall scenario variables. This depends on the nuisance likely to be caused and the implications of an area being temporarily flooded. The difference between a shopping area and an outdoor recreation area serves to illustrate this. A sports field being flooded will cause a lot less nuisance and damage than the flooding of a shopping high street. The calculation of the water drainage for a recreation area can be based on a less heavily weighted rainfall scenario, which makes it possible to save costs when putting the design into practice.


Also, the design and calculation of new and existing systems can be based on the options for temporary storage and/or infiltration of rainwater and, if required, the long-term retention of rainwater. The creation of storage and infiltration options often culminates in a plan that can be realised less expensively. It is of course important not to lose sight of the management and maintenance costs.


As well as making calculations for and designing rainwater drainage systems, InVra plus can also advise you on producing a design for dry weather drainage. We also have experience in the disconnection of rainwater in combined systems and are able to support our clients with this.

A good residential environment has an important effect on people's health and happiness. Design and incorporation present issues of an aesthetic, functional and technical nature. Our work often starts with checking the feasibility of urban building plans. The water management, traffic and sewer aspects and the laying of public green space are considered.


Our experience with the building of residential districts is put to direct use when we provide second opinions on urban building designs and produce the estimate based on outlines to determine the budget needed to bring the plans to fruition. Calculations and drawings are produced parallel to the development of the urban building designs. We are pleased to integrate sustainability in our plans.


At an early stage of the design process we consider the mass haul versus building heights and the water management aspect of the plans. The purpose of this is to minimise the transportation of soil from and to locations and to optimise the reuse of released soil materials. We draw on the latest developments in the area of public lighting and use materials that are as environmentally friendly as possible. That's how we help our clients to make choices regarding sustainable solutions and to integrate them in the public space policy.

InVra plus has been involved since its inception in major hydraulic engineering projects, such as Blauwestad, Meerstad, various waterway connections in Groningen, Drenthe, Overijssel and Germany and the building of salt marshes outside the dikes and the construction of the primary sea dike in Delfzijl.


In these projects we have played various roles, making outline designs for Design & Construct contracts on the one hand and going through the entire design process - outline design - preliminary design - detailed design - on the other. We are able to devote our years of experience to quickly producing a design, and we know where the biggest risks lie and which measures can be put in place to manage them.

InVra Plus has ample experience and knowledge of the design and application of various road surface structures. They include road surfaces made of concrete, asphalt or slab paving and top layers combined with bound or unbound foundations. The calculation method is based on design requirements and key principles such as traffic information and the bearing capacity of the subsurface and the road surface structure is worked out using calculation programs. The following software programs are used for this purpose: CARE, BISAR, OIA, CIMpel, VENCON, KMW, BESCON, UEC-SLAB.


During the design stage various road surface structures are calculated and mutually compared on aspects such as the costs and life cycle in order to decide on the most cost-efficient construction. Alternative compositions are also included in the comparison. Alternative compositions include AGRAC or stabilised AEC slag (waste from power plants).


As well as the 'standard' dimensioning calculations we have also calculated a road surface structure with extremely high bearing capacities for special vehicles, including reach stackers, and the storage of large quantities of bulk materials and containers. A foundation made of cement-bound AEC slag is used for this purpose. Various studies (and preliminary studies) can be carried out at our own laboratory before or during the implementation stage in order to guarantee the quality of the road surface structure from the sand fill up to and including the top surface.

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