Blocking isn't just for interstates anymore. Cones, flares etc are just to flimsy to stop a vehicle going even 25MPH(sorry I can't convert to km/h). A well place apparatus is going to be the safest barrier for fire/ems personnel.
Don't forget to block the road with apparatus. At least block the lanes that you are working in, plus one. And if you shut the road down completely, vests are not required.
The fire station that I work at has miles of highway that we are responsible for as the first in engine. Typically, we have a waiting time for the second in engine, so we have to set things up before the California Highway Patrol gets on scene as well. Firefighter safety is paramount here. Key point for response is that people tend to look at the incident and not the road... and this means both directions. And who can blame them? When you see something like this, how could you not look?
We have response from stations at both ends of interstate area. You'd be surprised how many "in the South bound lane" are actually in the North, and vice versa. We also use blocking, vests and designated safety officers.
Often times, there is simply no extra room when pulling off the roadway to enable close access to the MVA and to minimize transport distance for emergency equipment...
This is why you need to really think about where you are placing equipment on your rig. EMS and Extrication equipment for this reason need to be on the passenger side and rear compartments if necessary to afford maximum safety for firefighters. Is this a normal way for all of us to do business? It is for the rigs' I've seen. Roadway restrictions and traffic flow make responses incredibly difficult sometimes... even though you have pulled off the roadway as far as possible.