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Initial Blocking at Highway Incident Scenes

I would like to tackle a topic here that at times is one of the least discussed, and rarely trained on tactics in Traffic Incident Management; Initial Blocking. This can be especially true for Safety Service Patrol (SSP) professionals. A majority of incidents handled by SSPs are incidents that were not dispatched, or that they have had little time or information prior to arrival. The crew that I supervise experienced a situation like this recently, and his SSP truck was struck within minutes by a vehicle while setup as an initial block in an active travel lane. Fortunately, my operator only suffered minor injuries, and the distracted driver was not injured. Once again, it reminds us of the very real dangers of an occupation with a very high frequency of risk.

Many emergency vehicle struck-by incidents and secondary incidents occur during the 'initial' stages of an incident response. This is a critical time where the speeds of the approaching traffic are still high, the line of sight is poor or non-existent, and proper advanced warning is not in place. From a Safety Service Patrol perspective, it is imperative to understand the strategy required for initial blocking, the tactics used by other responders, and how to gain the most benefit for the safety of the responders, the involved motorists, other occupants, and other approaching traffic. It is an 'initial' maneuver because it is meant to be a short-term measure in the early stages of an incident and will likely change as the incident evolves or progresses.

The FD Engine's Initial block and it is a great example of a Lane + 1 Initial block of the shoulder, Ramp lane, and an adjacent active travel lane. Note the SSP Unit has arrived and set a cone taper to complement the block, and coordinate the traffic control established by the initial block.

The strategy of initial blocking is to protect the scene or incident from approaching traffic and allow the responder a short time to size up, gather information visually and verbally that will determine steps or actions to be taken, and prioritize those actions. Initial blocking is a tactic for every incident we respond to, or happen upon, whether it is a crash blocking multiple lanes, a brush fire near the roadway, debris in a lane, or a disabled vehicle on the shoulder. This initial action should determine and dictate early on the amount of traffic control resources or measures needed, and these measures should be communicated to other responders as quickly and clearly as possible using correct terminology. While it seems that we are simply 'parking' behind a disabled vehicle/incident on the shoulder, and 'blocking' when a vehicle/incident is in an active travel lane, if there is an incident of any type ahead of us on the highway lanes or shoulders the goals remain the same: Responder safety, the safety of involved motorists, and the safety of approaching traffic. Only the tactics change. When it comes to tactics, different responders have different objectives, and will employ different tactics.

There are many factors that determine the placement of the initial blocking vehicle or apparatus, and the type of block that will be utilized. Any other vehicles arriving at an initial blocking incident should adjust and coordinate efforts based on the initial blocker's needs. It is important to understand the types of blocks and what factors determine which type of block to employ. Any of these blocking maneuvers can be an initial block, or a primary block that will be used for a longer duration incident and that should include advanced warning, and temporary traffic control devices in place. Initial blocks are short term in nature and are also used commonly when clearing lanes or minimizing the impact for traffic in adjacent lanes. The first and most common type of block is the parallel block that used primarily on shoulders, and when staggering SSPs upstream of response vehicles in multiple lanes to guide approaching traffic to merge right or left.

The SSP Unit now set up on the shoulder with the cone taper readjusted as a primary block after FD/EMS have met their objectives of patient care and transport, and departed safely. Good communication, coordination, and cooperation of all Responders is the key to meet goals of safe, quick, clearance.

The next type of block is the angled block that is primarily used for blocking one or more lanes, or the shoulder and an adjacent lane. There are two angles used: Left or right. This block is used almost exclusively in the fire service as both an initial and a primary block when responding to roadway incidents, and at times the angle used is primarily more about protecting crews attending the pump panel, deploying hand lines, or accessing tools like extrication equipment, than guiding traffic. Always remember to avoid the Zero Buffer hazards when angled blocking and remind others on scene. Law Enforcement also uses angled blocks quite often and the angles used are not always focused on guiding traffic, but rather for shielding purposes, and other tactical reasons.

Another special consideration for SSP units is when an initial block is used to queue traffic, enabling personnel to establish traffic control with temporary devices and warning signs, or perhaps create a traffic break to allow a slow-moving vehicle to return to the travel lanes. This consideration comes from SSP units working as single units most times versus having multiple responders on the same incident. Another situation is being first on scene and aware other responders may be enroute with different priorities and needs. SSP units should consider allowing enough space that will allow Fire, EMS, Law Enforcement and Towing/Recovery access to the work area, but not compromise the safety of other motorists.

Many times, SSP units can become blocked in, or surrounded, prohibiting proper traffic control once other responders arrive. These other responders are far less likely to alter or change their vehicle positions once on scene and engaged in their duties. It is very challenging from an SSP standpoint to be first on scene, to block one or more active travel lanes, allow sufficient room for other responders, keep traffic flowing on an altered path, and not allowing traffic to cross back into or pass too close to the incident scene, thereby endangering responders and victims.

The downstream Incident Work Zone protected by the SSP Unit blocking to the rear, and downstream as well, guiding the traffic with Message board and cone taper. Special consideration was given here to Towing and Recovery by keeping the ramp closed it allowed for a quicker response and safer ingress and set up for Towing's objectives. Again, communication, coordination, and cooperation are the keys to safe, quick, clearance.

There may be times when an adjacent lane needs an initial block to deny access and guide approaching traffic in the direction needed to assist in establishing early traffic control. This type of initial block would be employed in an 'island' incident where traffic may be flowing actively around both sides of an incident until a primary block utilizing additional blocking vehicles, or temporary traffic control devices such as cones can be established. Sometimes this means initial blocking of a lane not affected by the incident.

Good communication, pre-planning, and training with other agencies is one way that SSP units can better prepare for initial blocks. Use this time to show the benefits of the proper use of this tactic no matter the various responder's objectives or priorities. All initial blocking should serve as a short-term measure that enhances the safety of all the responders. The initial block concept is flexible in nature and can sometimes easily transition into a primary block used for the duration of a small-scale incident such as a disabled vehicle with a flat tire. Just like on scene lighting, it is important to re-evaluate and reconsider the needs and purpose as the incident evolves. Understand that as a tactic it can be changed, enhanced, or scaled up or down as needed. Initial blocks used along with primary blocks can achieve objectives that will enhance scene safety, like expanding or minimizing work areas, creating safer termination areas, and enabling safer demobilization of incident scenes. Make your 'Initial' steps your first, but don't allow them to be your 'last'.

About the author John M. Sullivan:
John M. Sullivan is a Highway Response Supervisor 1 with the Tennessee Department of Transportation 'HELP' Unit serving Nashville and Middle Tennessee since 1999. John serves as a member of National Fire Protection Association Technical Committee (NFPA 1091), Standard on Traffic Control Incident Management Professional Qualifications for 2020. Mr. Sullivan is also a Lieutenant FF with the Pegram FD, and a TIMS, EVOC, and Vehicle Extrication Instructor. John has been married 20 years and he and his wife Teresa have a 13 year old daughter.

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