Special event security planning and street fairs
Recent reports of terrorist acts using motor vehicles to plow into crowds killing and injuring many at public events in Berlin, Beijing, and in the summer in Nice, France ("Truck attacks in Berlin and Nice reflect change in Islamic State tactics," Guardian) always reminds me of running farmers markets in Brookland, and the day an older man plowed through the sawhorses blocking the street because he saw no reason to prevent him from proceeding to CVS.
Fortunately, the market was over for the day, and who knows, maybe if there had been people in the street he would have stopped.
That wasn't what happened in 2003 in Santa Monica ("Ten Years After Tragic Crash, States No Closer To Solving Elderly Driving Problems," Autoblog) where 10 people died in a similar situation--an aged person driving through the crowded market.
There have been similar casualty events at street fairs since then ("Car Plows Into D.C. Street Festival, Injuring 35," Fox News).
In response, most communities have upped their traffic control requirements to include hardier barriers. But many times, events are allowed to slough off the requirements because of the cost.
water filled Jersey barriers.
They are expensive to rent (but relatively cheap to buy depending on how many you need) and at least the last time I had to close a street, DDOT would fill up the barriers for free, using their water truck--a filled barrier has almost 2,000 gallons of water.
But I have noticed that various street closures don't always use such an apparatus.
And neither does Eastern Market's weekend street closures--although for years I've recommended the installation of retractable bollards in the street at 7th Street and North Carolina Avenue, and at C Street (eventually I would like to see them installed at Pennsylvania Avenue SE too).
It appears that neither Jersey Barriers or bollards were part of the security plan for either the Christmas Market in Berlin or the farmers market in suburban Beijing.
It would have been hard to put them all along the route in Nice, but at various places, barriers could have been installed and this might have thwarted the attack there.
Street fairs and similar events must pay more attention to emergency preparedness on this dimension.