By Yanbing Wang
Our first bridge project was a Tag-along project with the University of Toronto team. We traveled in the summer of 2016 to help build a 34-meter cable suspended footbridge in Patzula, Joyabaj Municipality, Guatemala. The bridge supports 800 daily traffic, including 45 students, to safely cross the river.
Here we are, back from Paztula, the lovely little town located in the mountains under the municipality of Joyabaj in Guatemala. Below are some wonderful flashback moments that we would like to share with you. The primary source, of course, is my daily journal!
Digging the Excavation
The first few days were rough. Almost everybody had a blister on his or her hand for doing all the pickaxing and shoveling work. Both the foundation and the anchor pits needed to go an additional three-meter deeper on the west side because the design was assuming that the two bottoms were leveled. That was A LOT of dirt to dig!
Rebar cutting and bending was much more fun and a lot easier compared to the excavation that we dug for the previous days. Since the excavation was pretty much done, we had extra hands to cut and bend the rebar, not one, not two, but a team of six engineers. You might say it’s a waste of intelligence, but it’s actually to save our energy for more important tasks later. According to the design drawings that David (UofT’s primary designer of the bridge) and his men spent days on, we needed to make rebar cages out of three different sizes of steel rebar. One rebar cage was needed for each of the four towers, and one anchor cage was needed on both the east and west side of the bridge. The anchor cage would later be buried in the pit that we excavated really hard, secured by loads of heavy rocks and concrete on top, and would be staying there permanently to ensure that the anchors would stay still.
Q/C stands for quality control. It is one of the most important jobs on site because a small mistake on measurement may cause waste of material (rebar cannot be unbent after it’s bent wrongly) or even safety hazards. In order to be precise, we took multiple measurements before and after each cut or bend, as errors might accumulate after repetitive work. In addition to that, Q/C also ensured that the cement mixing ratio was correct. I learned from Mr. Boroto, our Q/C manager, how to count in Spanish while supervising and interacting with the locals.
Setting Cable Sag, Decking & Fencing
The two handrail cables and three walkway cables carry the major load of the bridge. Sags are required to be adjusted to the same level. Ethan (the B2P engineer) showed us how to adjust the sag without a cable puller. We unscrewed the clamps just a little bit each time, and hit the cable with a big stick so that the cable slid down a little. Not very far away from the anchor pit, an auto-level was set up to make sure that each cable was at its right position. After multiple attempts, the cables were clamped at their correct positions, and we were ready to put on the harnesses — for walking on the suspended cables to put on crossbeams and deck boards
The last few days of construction went really fast – decking and fencing only took a few days. We were already 5 days ahead of schedule. When it finally came to the inauguration day, the community prepared a grand celebration party in their school. The day starts with live Marimba music at 6 am. Vivian and I prepared for a short speech for the community (yes it was in Spanish, and we had little idea about Spanish before that. Special thanks to Mr. Boroto, Brad and Ethan for correcting our bad grammar and pronunciation). In the afternoon, almost everyone in the community gathered in the school to say farewell to us. It was a sad moment to leave the beautiful community and all the lovely charming kids. We will always miss them, and we hope that the suspension bridge will make their lives easier!