TEPO – Tsunami Evacuation Pedestrian Overpass

Thursday, July 22, 2010

One of the ideas for the next design class is looking into using pedestrian overpasses as evacuation structures. Pedestrian overpasses are very common in Indonesia in general and the ones in Padang performed well in the last earthquake. So we set out to do an initial assessment of the two that are currently in Padang.

From Padang Summer 2010

Tabing. There is one located in Tabing, right next to the train station. This one used to be outside of Basko Hotel but got moved to Tabing, probably because the government thought it would be used more. This one is made with steel.
Some concerns we have about this one:

• Floor panels – They were very thin and rusted. Maintenance is an issue.
  
  

  From Padang Summer 2010

  
  
  
• Connections to the ground – How deep do the bolts go? Are they bolted only to the concrete block?
• Usage – There are discarded cigaretts and graffti, therefore some people use it as a hangout.
• Dimensions:
• 24.24 m long (across the street)
• 2.20 m wide
• 6.3 m high (ground to deck)
• 2 m wide access (entrance)

From Padang Summer 2010

Andalas Plaza. The other one is located outside of Andalas Plaza. The stesp on the mall side of this one is heavily used by people hanging out. When we got there, a bunch of teenage girls were chatting on the steps. There is overhead covering for the stairs and bridge. This one has concrete supports and a metal deck.

• Stairs – Support for stairs looks thin: buckling issues. Flange for the column is only 6” wide. Some bolts are missing.
• Connection to the ground – Not sure how deep the concrete extends below ground.
• Connection to deck – Cannot see how the metal deck is connected with the concrete columns.
• Floor panels – Lots of rusted pieces everywhere. Pools of water. Floor has been patched with different panels. Very thin.
• Dimensions:
• 29 m long (across the street)
• 1.3 m wide
• 6 m high (ground to deck)
• 1.1 m wide access (entrance)

Comments about TEPO idea in general:
Everyday useage will be a big issue. If people don't use it regularly, then they will not think of using it during an emergency. Right now it is easier to walk across the street between traffic than to climb one of these things. The stairs are very steep (around 45 degrees?) and takes a lot of energy to get up. Perhaps escalators will help but they use electricity. At the Tabing overpass, we saw circuit boxes but they were empty.
Maintenance is another issue. In theory, the overpasses can hold a lot of people but the quality of the floor panels are questionable. It seems dangerous to pack a lot of people onto the structure and risk breaking the floor panels.

Capacity is an issue that was brought up at a KOGAMI meeting. They do not hold very much people and are not fully enclosed structure (like the inside of a building). So there is concern of people falling when more and more people try to cram into the space. But perhaps this issue can be solved by having bigger overpasses that straddle an entire intersection and having enough of them.

Not sure what the final solution for the TEPO idea will look like. A feasibility study will definitely be needed before the design of one. Perhaps a comparative study with another city where overpasses are heavily used and well maintained should be done. This could turn out to be a very interesting design project though.

At the time of this writing, we have not managed to get drawings from DTRTB.