Wednesday, February 17, 2010

How long to survey your Neighborhood?

The Mira Mesa CERT members got together on February 10th for a neighborhood survey by car drill. The goal was to determine how large of a residential section of Mira Mesa could be surveyed within thirty minutes using an automobile. The things we would want to identify during this type of search are which buildings are damaged and to what level, where are there road hazards or blockages, how will out of area responders (such as SDFD) get to various areas of Mira Mesa, and where would our CERT members best be used in the interim. The thirty-minute time limit assumed that the team did not have radios and needed to perform a physical check in with the Team Leader to update status and confirm that the team had not run into trouble.
The scenario we used was an major earthquake had struck on a weekday evening which meant that we would concentrate on residences rather than businesses. Since we had four people, we all got into my van after discussing the general search plan and discussing team member roles. Those roles included Driver, Navigator/Scribe, and Left and Right Spotters. We also discussed using three people (driver and two spotters) as an alternative to a four-person team. To give us a way to identify what level of “damage” the houses had, we used the number of cars (or other vehicles) in the driveway: one car – no immediately visible damage, two cars – minor damage, three or more cars – major damage. Cars on the street did not count and houses with no cars were considered unknown status. We got started about 6:30pm.

It was an eye-opening experience. The first challenge was apartments – there was no way to get an accurate assessment in a short period of time. Driving and Navigation quickly became a full-time jobs as we tried to wind our way through residential streets and cul-de-sacs. The pot holes from our recent rains did create real (although very minor) hazards and the Navigator had to find a route which minimized backtracking and loss of time. Our spotters did a great job identifying and categorizing houses for “damage” but we found that 15 miles per hour was the fastest we could go and still get a good count. By the time we hit our 30-minute “check-in time” limit, we had covered about half of the area I had expected to cover and that was without any route-stopping roadblocks or “victims” on the street to slow us down. According to my maps, we covered a 1/4 square mile area (about ½ mile on each side).
Lessons learned:

1) A four-person team is required to do this kind of survey. There is too much to do for any fewer people without major delays to the search.

2) The Navigator likely cannot be the Scribe due to overloading. Each Spotter would have to keep records of their damage assessments with the Navigator calling out street names so the Spotter can add them to add to their notes.

3) A radio with enough range for the survey area would allow the teams to extend their search time, allow immediate status updates and call for additional team members if the situation warrants it. Either the Driver or Navigator should be able to handle the radio duties without overloading.

4) A handheld GPS unit might be used to mark locations by dropping way points on its map grid and incorporating them in the Spotter’s notes.

5) An initial survey for major roadway access is key to all other responders arriving on-scene. This can be accomplished both by the “intelligence” gathered from team members as they check in with the Logistics people and reporting what they saw on the way to the rally point (both roadway access and building damage) and by actual survey of routes that remained in an unknown status.

6) Communities laid out in a grid-type street pattern could probably searched more quickly than the area we selected. However, if you want a quick assessment of damage, you will have to have a large number of survey teams conducting surveys simultaneously in multiple areas of the community.