By Randy Lloyd
In Harris County, TX-the third most populated county in the United States-first responders have adopted a next-generation preemption system that has significantly improved their response times and safety and reduced their risk of collisions when responding to 911 emergencies.
Regardless of speed, emergency vehicle drivers, including emergency command vehicles that must respond quickly, have influence over the circumstances that so often endanger motorists who don’t hear or see them coming into an intersection. Overly congested intersections, red lights in direction of travel, and oblivious drivers are just a few of the underlying problems that Harris County first responders have seen solved since incorporating their preemption system.
The company that developed the preemption solution is EViEWS Safety Systems, Inc. (EViEWS), a provider of traffic technology for the rapidly evolving world of intelligent transportation systems (ITS). The operating specifications for this preemption program for Harris County were designed by a team comprising a coalition of first responder leaders of Harris County communities and traffic engineers from Houston TranStar, a coalition of federal, state, and local authorities with responsibility for advancing intelligent traffic systems.
As first responders know, 60 seconds can make a difference between a successful emergency rescue and a deadly flashover. Having an engine company housed geographically within the standard eight-minute response zone, only to have to negotiate 15 minutes worth of traffic challenges, makes this goal rather ineffective. The first responder leaders of Harris County set out to counter these challenges with a goal of creating traffic corridors for seamless and faster safe passage for their emergency crews.
On one roadway, centerline medians were installed that exacerbated the problem, especially during peak times. EViEWS understands traffic and emergency vehicle flow and adjusts automatically to improve response times and lowers risk to all.
Chief Fred Windisch, of the Ponderosa (TX) Fire Department, states, “Our major east/west corridor is FM 1960 West/Cypress Creek Parkway. Our entrance onto FM 1960 is at Rolling Creek Drive, and after two years, the traffic count at that intersection was determined to be 65,000 vehicles per day. Remember, that is a 24-hour time period, and common sense tells us peak times are not 2 a.m. We need immediate access to enter the corridor and then to traverse east or west. EViEWS makes that happen by predicting our direction of travel and adjusting green times to allow the corridor to move more effectively. It is amazing to see positive results under real-time conditions on a consistent basis.”
Harris County System Overview
There are more than 22 fire districts, 54 fire departments, and a dozen EMS agencies in Harris County’s 1,800 square miles. Within these 1,800 square miles are more than 900 intersections. Currently, the EViEWS system is installed in more than 200 intersections, and the remaining intersections will be completed as the other fire districts obtain the necessary funding. In addition, there are also more than 75 emergency vehicles (EVs) currently equipped with the EViEWS system’s advanced transponders, with that number increasing as more vehicles and fire districts come online.
Once completed the EViEWS Safety system offers an 1,800-square-mile communications network with all 900 intersections and hundreds of networked emergency vehicles providing real-time preemption, real-time network monitoring, and extensive communication data management.
The EViEWS system is a fully integrated, scalable, and highly effective technology platform. The EViEWS systems are designed to combine a modular suite of solutions to enable a number of essential functions for government including EV preemption/prioritization, transit prioritization, traffic congestion mitigation, multiagency interoperability, global positioning system (GPS) tracking and information systems, and dynamic messaging.
First Responder Challenges
The sudden appearance of an emergency vehicle en route to an emergency can be extremely disruptive and dangerous to nearby vehicles as individual drivers maneuver to get out of the way. Some drivers become confused and create conflicts that can cause emergency vehicle crashes or block lanes, increasing response times. Using emergency vehicle preemption (EVP) systems to provide EVs with a green light at signalized intersections can increase operating efficiencies, reduce driver confusion, eliminate conflicts, reduce property damage, and improve emergency response times.
A key issue facing municipalities in the United States is the challenge of providing a clear passage for fire and rescue, law enforcement, and emergency medical services (EMS) vehicles as steady growth increases in populated areas. Local government officials must make decisions on how to provide appropriate levels of emergency service while at the same time coping with increasing demand for services and increasing congestion levels.
First responders, including fire and rescue, EMS, and law enforcement, operate in high-traffic areas such as city downtowns, heavily traveled corridors, shopping malls, convention centers, stadiums, and airports. While in these areas, first responders are at much higher risk for involvement in accidents themselves and are subject to unpredictable delays in reaching a hospital or the scene of a fire, accident, or crash site.
Significant economic benefits to cities and counties can be derived from the use of EVP equipment including eliminating or reducing lawsuits, claims, and torts resulting in multimillion dollar savings from intersection-related accidents, along with the attended reduction of property damage to emergency vehicles.
Fire chiefs state that emergency vehicle downtime is one of their major concerns because of the domino effects of lost productivity and the need for additional vehicles as spares.
Additional capital investment benefits can be realized when planning and implementing coverage for fire and rescue stations within new communities. National studies have shown that using EVP equipment allows larger coverage for stations and still maintains the national standards for flashover curve and cardiac arrest response times.
One means of offsetting the effects of congestion is installing EVP equipment at signalized intersections. This ITS technology provides a special green interval visible to the emergency vehicle driver while providing a special red interval on conflicting approaches. The EVP equipment detects vehicles approaching signalized intersections that are requesting the traffic signal controller to provide preferential signal indications for an approaching emergency vehicle. In general, the EVP equipment identifies a vehicle requesting priority treatment using either optical, acoustic, special inductive loop, or GPS radio-based technologies.
The concept of EVP and the potential benefits of prioritized traffic control to support emergency response are nearly as old as traffic signal control itself. Over the years, various concepts have been developed to provide emergency control of signalized intersections, but all have had several limitations, such as line-of-sight restrictions, slow speed detection capability, high installation costs, calibration issues, and frequent maintenance. Most also suffer from not providing an infrastructure that incorporates effective visual and audio emergency warning to motorists and pedestrians, clearance of downstream intersections, and pedestrian inhibit features. In addition, most EVP systems provide limited capabilities for transit signal priority and highway-rail crossings.
The EViEWS Solution
The EViEWS Priority System allows emergency vehicles to wirelessly communicate with intersections using a radio- or GPS-based implementation that transmits a digitally coded spread-spectrum signal from the vehicle at a distance of up to one mile along a non-line-of-sight path. This signal is transmitted every second to allow accurate calculation by the intersection module of the EV’s GPS position, speed, and direction. The vehicle location and speed data are used to provide optimized traffic signal prioritization. Signals are set to green on the EV approach and red for opposing signals.
Preemption call requests are sent to the signal controller on a real-time basis instead of a fixed distance. Higher-speed vehicles will trigger the controller earlier than lower speed vehicles, and if a vehicle stops or turns off the GPS approach path, the vehicle will not trigger the controller at all. Downstream intersections are also being prepared for the arrival of the emergency vehicles. The system tracks multiple vehicles and assigns priority based on vehicle type or first-come, first-served to ensure no conflict in the intersection.
Previous Market Preemption Systems
Many companies market specific applications such as signal preemption that provide a green light for a first responder approaching a single intersection at a time. However, these systems are expensive and high maintenance, lack security and scalability, and do not link to other traffic and emergency management systems. EViEWS is one of the only ITS companies that offers a comprehensive suite of technologies that provides core components to a comprehensive homeland security, public safety, and quality-of-life infrastructure.
RANDY LLOYD is president of EViEWS Safety Systems, Inc. Prior to being named president in 2013, he spent several years providing sales and marketing consultation to the company. Lloyd has conducted presentations to congressional staff members in Washington, D.C., to help further their understanding of the vast solutions available through the EViEWS system’s infrastructure. Lloyd served in Desert Shield and Desert Storm, where he was responsible for multiple missions throughout the Middle East, including assisting the Army’s global positioning system (GPS) asset tracking and accountability program. Lloyd has a bachelor’s degree in marketing from New Mexico State University.
The EViEWS Difference
The EViEWS Preemption and Prioritization System provides a number of features and capabilities. The following provides an overview of these features:
• The system operates in all weather, including heavy fog, and is not limited to a clear line-of-sight path for wireless communications between the intersection and approaching vehicles. It accommodates curved and hilly approaches and is able to preempt around corners. The system uses the unlicensed 900-MHz frequency band.
• The system dynamically adjusts the preemption range based on speed and estimated time of arrival (ETA) of the vehicle at the intersection. The onset of the preemption call to the traffic signal controller at the intersection is programmable for a specific number of seconds prior to the vehicle’s ETA, such as 25 seconds, regardless of vehicle speed.
• The intersection unit monitors up to 10 emergency vehicles that are involved in responding to an emergency incident. These vehicles can be from the same or multiple agencies and multiple jurisdictions. Each vehicle has a specific digital code.
• The system provides the vehicle’s ETA to determine the critical time for a preemption call. This approach ensures that the EV will have a green phase at the intersection and greatly improves the safety of the EV passing through the intersection.
• The system can automatically provide and manage a list of authorized vehicles at each intersection. The intersection module, prior to accepting a preemption call, authenticates each authorized vehicle. Authorized vehicles are listed and delisted individually or in groups.
• The system is an all-digital implementation, which does not include any analog adjustments. The satellite-based global positioning system (GPS) is used to determine exact vehicle position, speed, and direction. In addition, the GPS time information can optionally be used to provide time reference to signal controllers (timeserver), and incident time and date for logging purposes.
• The intersections and approaching vehicles maintain two-way communications by way of digitally coded radio signals. The radio system is also usable for remote programming of vehicle transponder and preemption equipment inside the traffic cabinet along with retrieval of preemption logs, thus avoiding the need to physically open the traffic cabinet and connect a portable computer.
• The system can automatically drop the preemption call when the vehicle has stopped at the emergency site, releasing any intersections downstream along the route from preemption. The vehicle preemption equipment is able to drop the preemption call by sensing the parking brake or National Fire Protection Association (NFPA) 1901, Standard for Automotive Fire Apparatus, lighting control has been applied, thus indicating the vehicle has stopped. Overall, the system can be customized based on the needs and wants of the end user.
• The vehicle preemption equipment operates in a hands-off mode-no operator intervention required-and automatically detects an emergency response condition when lightbars only or sirens with lightbars are activated.
• The system allows corridor preemption as intersections downstream can be preempted, whereas other preemption systems are limited to just the next intersection.
• The system allows the vehicle status to be forwarded over Internet Protocol (IP) intersection to intersection.
• The system can be equipped with emergency warning signs (EWS) for low-cost signage at intersections and dynamic message signs (DMS) for lane control, public safety messages, and other civic information. The signs are designed to be serviced without demounting the sign, contain removable inner boards, and have replaceable display modules. The signs can be controlled over a 900-MHz radio network and can monitor prioritization activity to display approaching vehicles.
• The DMS signs have built-in flash storage capability for 100 graphic or text images, high pixel density and refresh rate for clarity and readability of images, 10- by 10-inch brick modularity (1,024 pixels), and lightweight polycarbonate enclosures. The signs and intersection modules are National Transportation Communications for ITS Protocol (NTCIP) compliant.
• The system has modular central control software that provides EVP management, EWS and DMS sign image downloading and management, and GPS-based asset tracking.
Other EViEWS Features
• Left turn output activation for minimizing disruption to opposing traffic.
• Multiple output activation triggers for preemption/prioritization optimization.
• Left/right turn monitoring for “Preemption around corners.”
• Pedestrian Inhibitor-prevents pedestrians from crossing intersection.
The EViEWS System “Avoiding Conflict” at the Intersection
• The system contains a small in-vehicle display that provides the operator with four indicators including intersection right-of-way priority (blue), intersection conflict resulting from multiple vehicles in a single intersection (yellow), system malfunction or lack of GPS satellite signal (red), and authorization (green). This in-vehicle display feedback of intersection status to the operator greatly reduces stress and anxiety on the operator.
• In the event multiple vehicles are requesting preemption or priority of a single intersection, only the first that will arrive at the intersection will receive confirmation of intersection ownership. All other vehicles will receive a conflict indication.
• After the owning vehicle passes the intersection, other vehicle requests are reevaluated and conflict or ownership indicators may change based on current conditions and vehicle position relative to the intersections.
• Only one vehicle at a time may own an intersection, and vehicles on the same direction and path may move from conflict to ownership as vehicles pass through the system.
• For safety purposes, once a vehicle is determined to own an intersection, that intersection cannot be owned by another vehicle until the vehicle has cleared the intersection or the vehicle request is terminated.
• The system allows prioritization transfer of ownership to higher-priority vehicles on bumpable segments. This will allow low-priority (transit) vehicles to relinquish ownership to emergency vehicles, provided that the transit vehicle is far enough away that it makes sense and is safe.
• Other equipment, however, can also be configured by time to intersection and a call advance to account for intersection clearance prior to actual preempt/priority service.