Bidding for a microtunnel or a pipe ramming with a low level of uncertainty requires that the project clearly define not only the route, but also the actual execution conditions, acceptance criteria and environmental constraints. When this information arrives incomplete at the bidding stage, the probability of scope revisions, design modifications, construction stoppages and cost or schedule deviations increases.
In this type of project, well-structured technical documentation makes it possible to better assess feasibility, compare bids on a homogeneous basis and reduce critical decisions during execution. In addition, it makes it easier for the technical assistance and engineering anticipate the main construction risks before mobilizing equipment and civil works.
Geometry of the layout and implementation constraints
The project must precisely define the geometry of the crossing: ground plan, longitudinal profile, entry and exit elevations, total length, minimum and maximum coverages, service slope and possible bending radii. This information is essential for selecting the methodology, sizing the thrust, assessing performance and checking compatibility with the planned pipeline.
It is also advisable to describe from the outset the space available for the construction site, including accesses, storage areas, urban or industrial constraints and vertical wells and reception. In many projects, the risk is not only in the subsurface, but in the lack of operational space or in the interaction with traffic, facilities in service or existing easements.
Necessary geotechnical and hydrogeological information
One of the most important points to bid with less risk is to have a sufficient geotechnical basis consistent with the length and complexity of the crossing. The project should include borings, laboratory tests, stratigraphic description, presence of boulders, fills, rock, soft or abrasive soils, as well as the water table and its possible variations.
This information conditions the selection of the excavation system and the face control strategy. It is not the same to design a crossing in stable ground as in saturated, heterogeneous or abruptly changing soils. For this reason, the geotechnical definition must be aligned with the planned construction solution, whether it is a pipe ramming conventional, a microtunnel or a specific solution for infrastructure crossings.
Pipeline definition and performance requirements
Another essential block is the characterization of the pipe to be installed. The project must indicate inner or nominal diameter, material, pipe length, jointing system, sealing requirements, design loads, service pressure if applicable, corrosion protection and durability criteria. It must also be clear whether it is a definitive pipeline or a jacket to accommodate a subsequent pipeline, because this changes design criteria, tolerances and acceptance.
When the pipeline operates under gravity, grade and geometric accuracy become even more important. When working under pressure, the focus shifts to watertightness, structural integrity and pre-commissioning tests. The more defined this part of the project is, the less interpretation there will be during the tendering process and the less risk there will be of subsequent changes.
Affected services, permits and environmental restrictions
To reduce changes and cost overruns, the project must also identify affected services and surrounding administrative or operational constraints. This includes existing networks, roads, railroads, watercourses, public water domain, port area, easements, time constraints, environmental requirements and access conditions.
In a trenchless crossing, these variables can have as much impact as the geology itself. An insufficient detection of interferences or an incomplete definition of permits may force to redesign wells, modify work sequences or reschedule works. Therefore, before putting out to tender, it is advisable to review not only the layout, but also the actual constructability of the crossing and its fit with the infrastructure or service to be kept operational.
Control criteria, acceptance and final documentation
The project must indicate from the bidding phase what controls will be required during execution and what criteria will be applied to final acceptance. It is advisable to define axis, elevation and slope tolerances, topographic controls, production follow-up, work records, acceptance criteria for the layout and final tests on the pipeline.
It is also useful to anticipate what documentation should be provided at the close of construction: as-built drawings, progress records, material certificates, test results and any information needed for operation and maintenance. When these requirements are defined from the outset, disputes between the developer, project management and contractor are reduced.
Why better project definition reduces bidding risk
A better defined project not only improves the technical quality of the bidding process. It also makes it possible to receive more comparable bids, with fewer open assumptions and fewer hidden price contingencies. In practical terms, this translates into a more realistic assessment of the deadline, a lower probability of modifications and better planning of civil works, equipment and logistics.
At Eurohinca, this preliminary analysis forms part of the logic of the technical assistance and engineeringReview layout, terrain, pipeline, constraints and acceptance criteria prior to execution helps to reduce uncertainty and provide a more robust solution from the outset.
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