When constructing a bridge for dual carriage to carry pedestrians, selecting the most appropriate construction method will rely on a number of factors, such as the bridge's length, site conditions, budget, and construction duration. A deviation will need to be implemented in order to provide safe and sustainable crossing for pedestrians over the dual carriageway. Most rural travel takes place on local footpaths, tracks and village roads, this is to provide essential access to water, wood, farm plots and road networks. A very common issue that communities and/or the local government face is inadequate crossing. Inadequate cross can prevent access to these services. 

(Footbridge in Barking, London image)
 

(A6 dual carriageway with footbridge running through image)
Therefore, a footbridge over the dual carriage will be best option to solve to this problem. The bridge will be constructed with precast concrete. This method involves the fabrication of the footbridge to be assembled off site in a manufacturing factory and then assembled on site. The use of precast concrete can reduce construction time by avoiding on site work. This includes the installation of formwork, which can take a rather long time to construct. Since it is manufactured off site at a factory, the quality of the concrete deck can be improved or changed. Precasting bridge parts off site is very advantageous as bridges are one of the most expensive objects to construct, it also allows for safety benefits, it lowers disruption to traffic and increases overall convenience for road users. During the production of precast objects in a plant and their subsequent installation, they undergo both prestressing and post-tensioning. Prestressing in the plant plays a crucial role in enhancing performance, particularly in terms of tensile strength. By inducing compressive stresses in the panels, it effectively prevents cracking and strengthens them, making them more resistant to bending and torqueing during manipulation on-site. This durability significantly reduces maintenance costs over the lifespan of the roadway and lowers user costs by minimizing the need for repairs. Post-tensioned panels have demonstrated the ability to provide the same design life as thicker conventional concrete pavements, but with the advantage of using thinner slabs. For instance, a 200mm post-tensioned pavement can have the same design life as a 355mm conventional pavement. Moreover, post-tensioning enhances durability by minimizing or eliminating cracking and promoting load transfer between individual panels, as they are effectively tied together.
 

In addition, the utilization of high-performance precast concrete requires less concrete compared to in situ concrete, resulting in time and cost savings. This reduction in concrete usage is beneficial, as it helps offset the carbon emissions associated with cement manufacturing. Precast concrete structures also offer advantages such as minimal maintenance costs, lower heating and cooling expenses. Over the life of the structure, the concrete can reabsorb up to 40% of the carbon emissions. Furthermore, at the end of their lifespan, precast structures can be recycled, contributing to sustainable practices.
This is the task
 A late revision to the road project includes a slight deviation around some woodland. However, the deviation will include the construction of a bridge. You are asked to put together a report that discusses, proposes and justifies why the deviation needs to be made and what construction methods will be used to construct the bridge. Remember the road is a dual carriageway - but also needs to carry pedestrian traffic. The report (about 1500 words) should have discrete sections that address environmental contexts, quality contexts, and geotechnical contextsBelow is my answer to the previous question. Hopefully, this can provide some background. I passed this question but the next question i failed.. and econo
mic contexts.
Evaluate the environmental, quality, geotechnical, and economic contexts of a given civil engineering problem.