Overview

The bridge that the village of Gidi requested, on EWB-UWP’s initial visit in ’07 and again during the August 2008 trip, was chosen to be implemented in August 2009 by the chapter as the first large scale project in the area.  The bridge project was selected based on the chapter’s belief that it would serve the greatest need of the people in the project area and was the most feasible for the chapter to complete of all realistic potential projects.

The Problem

The needs being met by the bridge in the project area are twofold. Firstly, the children of Gidi could not reach the nearest school, approximately 2-1/2 miles away, during the wet season.  Secondly, adults in the area were unable to reach a train station, located 1/4 mile from the village of Gidi, during the wet season.  The train is essential to economic growth of the village.  Only larger city markets provided a stable source of income and those markets could be easily reached via the train.

The train is essential to economic growth of the village.

The cause for the inaccessibility of these crucial areas during the wet season was due to a stream with a very wide flood plain.  This stream swells to a depth of three to four feet and a width of roughly 130 feet during the two wet seasons that occur each year.  The flooded stream prevented the children of Gidi from attending school and adults from using the railway station several weeks out of the year.

Prior to the August 2009 implementation project, the village had been using two, approximately 6×4-inch, eight foot long reinforced concrete beams to cross the stream in the dry season. To the chapter’s knowledge, no other prior attempts had been made to bridge or establish a crossing for the flooded stream.

Our Solution

The implementation of the Gidi footbridge project was completed over the course of 10 days from August 9, 2009 through August 19, 2009. The project proceeded smoothly and was finished four days ahead of schedule. The three contingency days that were in the schedule were also not used as work days.

The bridge team was separated into smaller teams consisting of carpentry/formwork, earthen embankments, rebar, and foundations. The separate work teams allowed multiple individual tasks to be accomplished simultaneously. The project mentors provided guidance on the more difficult tasks while the students directed the people of Gidi on specific tasks. Digging of foundations was the first task and was mostly completed by the people of Gidi. The footings were dug in two days and both footings were poured on the same day. Concrete was mixed using a single sack diesel powered concrete mixer, delivered at the end of the second day of the trip.

Rebar for the footings was cut by field measurements while the rebar for the abutments and wings were cut according to plan. Field measurements were required for the footings because the sizes and skews were changed due to a field-fit process. The footings were raised approximately two feet due to a high ground water table on site. The rebar was sunk into the ground to account for the extra length.

The falsework for the bridge deck was finished on a Sunday.  Although Sunday is a day of rest in Gidi, villagers arrived in the afternoon to assist in the assembly of the deck false work.  The following days, frames for the beam formwork were carried onto the bridge as well as the rebar cages for the beams. The formwork for the beams was prefabricated in sections on Saturday, Sunday, and Monday so that it was immediately available when needed. On Monday the deck was poured.  The beams were poured on the following Tuesday and Wednesday. Again, due to lumber constraints, only one beam could be poured at a time.

The final pour was completed on the tenth day of the implementation trip. There was never a problem with the mixer or gas powered concrete vibrator and materials were consistently on site.  Throughout the entire process, members of Gidi were voluntarily doing the majority of the manual labor. This included digging out the footings, tying rebar, nailing wall forms together, carrying materials from the village, assisting in concrete pours, and moving earth for the embankments leading up to the bridge,  along with various other tasks.

On the twelfth day of the implementation trip the bridge team returned to remove finale formwork, cleanup the work site, and hold a village meeting to discuss bridge maintenance.  The clean up and formwork removal went smoothly as did the village meeting.  The most important part of the meeting was to notify the village that the falsework beneath the bridge could not be removed until 21 days after the beams were poured or September 8th, 2009.  This and other maintenance tasks were clearly understood by the village leaders during the meeting.