There is an art to properly and effectively blocking traffic with an emergency vehicle at a highway incident scene. The driver must have an uncanny feel for the size of his or her vehicle regardless of whether it is a sedan or a 40-ton, tandem-axle ladder truck.
The process of blocking is done by the apparatus driver just as the vehicle comes to a stop at the incident scene. With the intent being to physically block the shoulder of the road and the closest lane of traffic or to block off several lanes of traffic, the emergency vehicle slows and before coming to a complete stop, makes a sharp turn to the right or left. This slants the vehicle at an angle across the lanes of traffic.
The assignment for the apparatus driver at this point is to use the apparatus to completely block the lane or shoulder area obstructed by the damaged or burning vehicle ahead of it PLUS one additional lane of traffic. A block to the left puts the officer's side of the vehicle closest to the incident. A block to the right typically puts the driver's side of the vehicle in a more shielded position.
When blocking with smaller vehicles such as police cruisers or an SUV driven by a chief officer, the block should be to the right whenever possible. This places the driver's side of this smaller vehicle downstream, making it a more protected side of the vehicle to exit from.
Ambulance Positioning
All ambulances must be positioned in a protected location at a highway incident scene. There are no excuses to this requirement. Many line-of-duty deaths have occurred during patient loading; a time when everyone is looking into the ambulance with their back turned to upstream traffic.
The downstream protected activity area created by the block of a major apparatus is the first place to consider for parking the ambulance. In addition, with the goal being to maximize protection of the patient loading area at the back of the vehicle, the ambulance driver should also complete a slight block to the right or block to the left with their vehicle. This small blocking angle places the rear of the vehicle away from moving traffic making it safer for personnel when loading the stretcher into the ambulance.
Critical Wheel Angle
All vehicles that position at a highway incident scene MUST be parked with their front wheel turned to their "critical wheel angle." This requires the steering wheel to be turned all the way to the left or all the way to the right; whatever is required to turn the wheels away from the protected activity area.
In the event that this blocking vehicle is struck in the rear by an approaching motorist, having the wheels turned away will hopefully move the colliding vehicles away from the rescuers at the scene.
Apparatus Lighting
Once at an incident scene and in a blocking position, the operator must initiate stationary light shedding procedures. Depending upon department protocol and apparatus design, things should happen once the parking brake is set on all major apparatus. Smaller vehicles such as police cruisers and chief's vehicles typically require the operator to manually control their stationary lighting.
With the requirements of the latest edition of NFPA apparatus standards in place, fire vehicles now 'shed' their white color strobe warning lights once the vehicle stops at a scene. In addition, most roof-mounted warning lightbar manufacturers now offer the option of shedding all forward-facing lights so to not distract traffic moving in the opposite direction.
Highway safety engineers also strongly advocate the use of amber (yellow) warning lights instead of red on emergency vehicles parked at highway scenes. New NFPA 1901 complaint apparatus have amber rear warning lights specifically for this purpose. Studies show that the motoring public psychologically responds to amber lights better, thinking of it as just another highway construction or repair project. They don't "rubberneck" as much at the scene when everything is yellow.
Introduction to Part 4: Personal Survival Skills
Now, you've arrived at a highway crash scene. Your vehicle is in a blocking position and light shedding procedures have been accomplished. It's time to get out onto the street and deploy some advance warning devices. In Part 4 of this series, we'll address personal survival skills for responders working in or near moving traffic.
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