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Effectiveness: 5 Star Cost: Varies
Use: Low
Time: Medium

SSC enforcement (previously referred to as automated speed enforcement cameras) is a technological system that can be used to enforce speed limits as part of a broader speed enforcement program. SSC enforcement is not intended to replace traditional speed management strategies but can be used as a supplement to other speed management techniques—HVE, traffic calming, and social norming—to alter driver speeding behaviors (NHTSA & FHWA, 2023). SSC systems are an FHWA Proven Safety Countermeasure (Office of Safety, 2021) that can reduce roadway fatalities and injuries by 20% to 37% (Montella et al, 2015; Li et al., 2015).

SSC systems function by capturing violations, recording relevant data about the violations, and recording images of the violator vehicle and license plate (only when triggered by infractions), and when validated, issuing citations to violators. Generally, there are three types of SSC systems used (Office of Safety, 2021):

  • Fixed, stationary units that monitor speeds in a single location (e.g., at an intersection);
  • Point-to-point (P2P) systems that use cameras to measure the average speed of vehicles (by license plate, typically) over a certain distance between the two cameras to determine if drivers are speeding;
  • Mobile units that are typically mounted on a vehicle or trailer and cycled between locations to distribute enforcement efforts.

Some States hold drivers responsible for violations; others hold the vehicle owner accountable for the violation (and sometimes for identifying the driver, if they deny culpability as the driver). A driver-liable approach may require a more involved process and may need to include an image of the driver, which can affect privacy concerns. Review and processing of citations in such States is generally more intensive in nature and places a higher burden on the State to identify the driver for a conviction or finding of responsibility (NHTSA & FHWA, 2023). However, some States that hold the driver liable, tend to assign a range of higher penalties, and may apply penalty points against the license of the driver as with regular traffic enforcement (Miller et al., 2016).

Other jurisdictions use a registered owner liability approach to enforcement. The processes for this approach are generally more limited and are not reliant on charging the actual driver of the vehicle; the owner is assumed to be the driver. This approach places the burden on the registered owner, like a parking ticket (Maisel, 2013). In many cases, the only defenses would be in cases where it can be demonstrated the vehicle had changed ownership, was stolen, or an error occurred in processing the citation. In general, more citations of this type may be processed.

More information can be obtained from national guidance resources. U.S. DOT released automated enforcement program and operational guides with information on identifying problems and setting up and maintaining an effective and transparent, community-supported enforcement program using speed cameras (NHTSA & FHWA, 2008). An update of the Speed Safety Camera Guidelines was released in early 2023 (NHTSA & FHWA, 2023). Eccles et al. (2012) developed a guide for SSC enforcement programs for NCHRP. A program checklist, jointly developed by several safety agencies, is also available to help guide jurisdictions who may want to use these tools (AAA et al., 2021).

In 2011 and 2012 NHTSA surveyed agencies with current or recently discontinued SSC programs (Miller et al., 2016) and found that many agencies seemed unaware of the existence of the national guidelines intended to help jurisdictions develop and operate effective, reliable, and publicly supported safety programs. Another key finding was the frequent lack of strong stakeholder and community engagement in developing programs, a Key Recommendation for effective and reliable programs.


SSC systems are used extensively in other industrialized countries and were first employed in the United Sates in 1987 (Miller et al., 2016). As of 2018 speed cameras were being used in approximately 137 jurisdictions in 14 States and the District of Columbia (GHSA, 2019; IIHS, 2019b).

The type of SSC system that will be most effective for a particular type of speeding problem depends on a variety of factors. These factors include the duration of speeding problems, whether speeding behavior is localized to a specific site or more widespread, differences in speeding behavior at different locations along a road, legality of different types of SSC, potential sight barriers that may bar cameras from monitoring a sufficient distance within its installation, and the number of lanes that need to be monitored. FHWA Office of Safety (2021) identifies which SSC type may be most useful based on these criteria, reproduced below:

Use Cases for Different SSC Systems Based on Various Criteria

 Selection Criteria 

Fixed Units 

P2P Systems 

Mobile Units 

Problems are long-term and site-specific 

Problems are network-wide, and shift based on enforcement efforts 

Speeds at enforcement site vary largely from downstream sites 

Overt enforcement is legally required 

Sight distance for the enforcement unit is limited 

Enforcement sites are multilane facilities 

Source: FHWA Office of Safety, 2021


SSC systems have been found to improve safety, but program parameters and site selection factors may affect both safety outcomes and program sustainability.

The use of speed cameras can contribute to reductions in speed and crashes. Decina et al. (2007) reviewed 13 safety impact studies of automated speed enforcement internationally, including one study from a U.S. jurisdiction. The best-controlled studies suggest injury crash reductions relating to the introduction of SSCs are likely to be in the range of 20 to 25% at conspicuous, fixed camera sites. Covert, mobile enforcement programs also result in significant crash reductions area-wide (Thomas, Srinivasan, et al., 2008). Similarly, in South Australia, injury crash data for 35 safety camera intersections for 5 years before and after the speed camera installation showed an estimated reduction of up to 21% (Kloeden et al., 2018). Wilson et al. (2010) reviewed 28 studies of automated enforcement including from U.S. sites and found reductions of 8 to 49% for all crashes and reductions of 11 to 44% for crashes related to serious injuries and fatalities. In Great Britain the effects of fixed speed cameras on crashes were estimated by examining data from before and after camera installations at 2,500 locations. Researchers estimated that installing another 1,000 cameras could prevent approximately 1,130 collisions and approximately 330 serious injuries (Tang, 2017). In France 2,756 speed cameras were installed from 2003 to 2010. A program evaluation estimated that the cameras prevented around 15,000 road traffic deaths during that time (World Health Organization, 2017). Lowering speed enforcement thresholds of automated enforcement also helped reduce mean speeds in Finland (Luoma et al., 2012).

Crash-based evaluations from the United States and Canada have also reported safety benefits from SSC programs in urban areas. Shin et al. (2009) examined effects of a fixed camera enforcement program applied to a 6.5-mile urban freeway section through Scottsdale, Arizona. The speed limit on the enforced freeway was 65 mph; the enforcement trigger was set to 76 mph. Total target (off-peak/free-flow) crashes were reduced by an estimated 44 to 54%, injury crashes by 28 to 48%, and property damage only crashes by 46 to 56% during the 9-month program period. In addition to the crash reductions, average speed was decreased by about 9 mph and speed variance also decreased around the enforced zones. Another finding from this study was that all types of crashes appeared to be reduced, except for rear-end crashes, for which effects were non-significant. Thus, there were no obvious trade-offs of decreases in some crash types at the expense of others. The program effects should be considered short-term. There was also very limited examination of spillover effects, including the possibility of traffic or crash diversion to other routes, but given that the corridor was a free-way, diversion to other routes may not have been an issue.

Mobile speed camera operations were also effective on non-freeway streets in North American urban areas including Charlotte, North Carolina; Montgomery County, Maryland; and Edmonton, Alberta, Canada. Crashes and speeds were reduced as a result of a mobile camera enforcement program and publicity on 14 urban arterials in Charlotte (Moon & Hummer, 2010). Publicity alone (before ticketing began) was associated with an 8 to 10% drop in total and fatal crashes. Once enforcement began, the program was associated with reductions of 19% in total and 17% in fatal collisions. These safety effects continued after the program was suspended before gradually returning to pre-intervention levels. A 2016 update of a long-running Montgomery County program found that mean speeds remained lower on treated corridors and lower than comparison sites (Hu & McCartt, 2016). The percentage of vehicles exceeding limits by more than 10 mph decreased an average of 64% at camera sites, 39% at spillover sites, and 43% at comparison sites lacking camera enforcement.

Several studies have been performed on an overt, mobile photo enforcement program in Edmonton. Speed limit violations were reduced both up and downstream of the enforcement locations, which were 7 two-lane urban arterials and 2 collectors with speed limits of 50 km/h (31 mph) (Gouda & El Basyouny, 2017a). Note that some studies have found a tendency for speeds to increase upstream of camera sites and for speeds to change suddenly both upstream and downstream of camera sites (De Pauw et al., 2014). A high-quality, crash-based evaluation estimated that severe crashes (fatal and all injury crashes) were reduced by 20% and speeding-related crashes by 19% (Li et al., 2015). Also, effects were much greater (32% reduction) on segments that were enforced over all the study years (compared to 18% for those that were not enforced in all years) and were also higher on corridors that had at least 3 speeding-related crashes before the enforcement started. A later analysis found a dose-dependent effect on crashes, with safety benefits increasing as the number of enforced sites and issued tickets increased. However, shorter intervals at each site, and greater spatial coverage were also associated with more safety (Li et al., 2017).

In Europe and Australia point-to-point -- also called average speed or speed-over-distance enforcement -- is gaining in popularity to reduce speeding and improve safety in freeway or limited access situations (Soole et al., 2013). Automatic plate recognition and time stamps are used to match vehicles and detect speeding from a first to downstream camera sites. If the average speed for the section is above the enforced speed threshold, a citation may be issued. It is not necessary to monitor vehicles along the entire length of road (NTSB, 2017).

In a review of international evidence this type of SSC system has been found to improve compliance to very high rates (Soole et al., 2013; De Pauw et al., 2014), and reduced speed variation since a majority of motorists travel at speeds closer to the limit (Soole et al., 2013). The technology also has been found to contribute to significant crash reductions (Høye, 2015; La Torre et al., 2019; Montella et al., 2015). Such systems have the potential to smooth traffic flow and may help to avoid negative halo effects such as rapid slowing or speeding up that fixed or overt mobile enforcement sites sometimes experience (Soole et al., 2013). An evaluation of 237 motorway sections in Italy estimated significant reductions for single-vehicle non-injury crashes, multivehicle fatal or injury, and multivehicle non-injury level crashes for motorways with various AADTs. Overall, a 22% reduction in crash frequency was estimated on the Italian motorway network (La Torre et al., 2019). Even greater crash reductions were estimated for a single urban, ring-road motorway (Montella et al., 2015).

In summary, conspicuous speed safety cameras tend to reduce speeds and crashes at treated sites. There is likely a dose-dependent response of amount of enforcement (number of sites, number of issued tickets) and safety effects achieved (Li et al., 2017). Area-wide crash reductions have also been found, but research on area-wide safety effects is more limited (Thomas, Srinivasan, et al., 2008). Specific times may be leveraged to increase program effectiveness through deployment allocation strategies (Kim et al., 2016). It is likely that covert enforcement, also used in Australian programs to increase drivers’ perceived risk of being detected, would increase effectiveness over various times and distances.  When applied on urban arterials, fixed units may reduce all crashes by 54% and injury crashes by 46% (Shin et al., 2009), P2P units may reduce fatal and injury crashes by 37% (Montella et al., 2015), and mobile units may reduce fatal and injury crashes by 20% (Li et al., 2015).


Costs will be based on equipment choices, operational and administrative characteristics of the program, and specific negotiations with vendors. Cameras may be purchased, leased, or installed and maintained by contractors for a negotiated fee (NHTSA & FHWA, 2023). Most jurisdictions contract with private vendors to install and maintain the cameras and, to process images and violations. Operating costs of SSC systems vary based on the nature of the system, administrative costs, and negotiated fees to vendors providing services to a jurisdiction. Many systems are “turnkey” operations, in which a vendor provides all of the equipment, vehicles, and support services necessary to collect violation data and issue a citation. The cost for this service may be based on a fixed monthly fee, or on a negotiated fee for issued or paid citations.

Costs to communities or States for the installation of fixed equipment can vary based on the type of system, the number of devices in use, and the type of sensors being employed to collect violation data. Jurisdictions must make the return-on-investment decisions for accepting these costs based on their determination of need, risk versus mobility assessment, and budgetary projections and constraints.

Fixed camera costs may not be like those for red-light camera programs, based on volume of activity and violations they generate. An economic analysis estimated the total cost savings of the Scottsdale freeway fixed speed enforcement were from $16.5 to $17.1 million per year, considering only camera installation and operational cost estimates and crash cost impacts (other potential economic impacts were not considered) (Shin et al., 2009). Chen (2005) provides an extensive analysis of the costs and benefits of the British Columbia, Canada, mobile speed camera program and estimated a societal savings of C$114 million and a savings of over C$38 million for the Insurance Corporation of British Columbia (ICBC) that funded the program. Gains et al., (2004) reported a 4:1 overall societal cost to benefit ratio of operating the national (fixed) speed camera program in the U.K. based on 33% reductions in personal injury crashes at camera sites and a 40% reduction in the number of people killed and seriously injured. Also, Tang (2017) estimated net benefits of installing 1,000 cameras to be around £21 million in Great Britain based on data from 2,500 fixed cameras crash data.

Time to implement:

Once any necessary legislation is enacted, automated enforcement programs generally require up to 9 months to plan, publicize, and implement.

Other considerations:

  • Recent types of automated enforcement: Washington, D.C., has implemented camera-supported enforcement to help enforce compliance with stop signs, as well as yielding to pedestrians at crosswalks (District Department of Transportation, 2022) but no evaluations for these uses are available. South Australia uses fixed SSC units, including at midblock locations, as well as combined speed and red-light cameras at intersections, pedestrian, and railway crossings, in addition to P2P systems (average speed over distance) camera enforcement (Kloeden & Hutchinson, 2019). Data show that speeding offense rates decline rapidly in the first 2 to 3 years of speeding enforcement and have continued to decline. Red light running has also declined, but not as consistently (Kloeden & Hutchinson, 2019).
  • Partnerships: It is widely acknowledged that SSC can be an enforcement multiplier and may be used in locations or at times that are difficult or dangerous to enforce by regular traffic patrol. SSC systems are not intended to replace traditional enforcement but offer an objective method for citing speeders and combined with effective publicity, enhancing widespread, general deterrence. State DOTs are considered good safety partners for identifying locations for deploying SSC based on speeding and crash concerns that cannot be addressed by engineering countermeasures (NHTSA & FHWA, 2023). Washington and Shin (2005) caution that simpler and less expensive engineering solutions (e.g., signal operations modifications, improving motorist information, and physical improvements around intersections) should be sought before implementing camera programs. In addition, a wide variety of other partners including community members should be consulted in developing an effective, community-supported program (NHTSA & FHWA, 2023).
  • Laws: Many jurisdictions using SSC are in States with laws authorizing its use, and specific legal authorization is strongly recommended to avoid potential court challenges (NHTSA & FHWA, 2023). Some States permit automated enforcement without a specific State law. Others prohibit or restrict some forms of automated enforcement (GHSA, 2018a; IIHS, 2019a). In yet others, there is no specific statute, and it cannot be inferred from case law whether the State allows automated enforcement. As of December 2018 nine States permit the use of speed cameras under at least some circumstances, 13 States have laws that prohibit speed cameras, and 28 States have no laws addressing speed camera use (GHSA, 2018a).
  • Publicity: Publicity is an important component of speed safety camera programs, from the planning stage onward (NHTSA & FHWA, 2023). Reductions in crashes in Victoria, Australia, were attributed to a television advertising campaign that supported, but did not relate directly, to automated speed enforcement initiatives (Bobevski et al., 2007). Publicity can also enhance perceived fairness of the programs. The use of warning signs for drivers to indicate the presence of automated enforcement systems within the community, and in the approaches where the technology is deployed, is highly recommended. These signs enable drivers to come into compliance before a crash or enforcement event occurs and provide fair warning to drivers of potential enforcement action in general.
  • Public acceptance: A 2011 nationally representative survey of drivers found that 86% thought SSC systems would be acceptable to enforce speed limits in school zones. Significant majorities also thought they would be acceptable at high-crash locations (84%), in construction zones (74%), and in areas that would be hazardous for police officers to stop vehicles (70%) or would cause congestion (63%). Thirty-five percent thought automated camera enforcement of speeds is acceptable on all roads (Schroeder et al., 2013). Support appears highest in jurisdictions that have implemented red-light or speed cameras. A survey of District of Columbia residents found 76% favored speed cameras, with even higher support among non-drivers (Cicchino et al., 2014). Interestingly, support was lower for measures not currently in use, including photo-enforcement of stop signs (50%) and yielding at crosswalks (47%). Again, support was higher among non-drivers for these measures (Cicchino et al., 2014). However, efforts to institute SSC often are opposed by people who believe that speed or red-light cameras intrude on individual privacy or are an inappropriate extension of law enforcement authority. They also may be opposed if they are viewed as revenue generators rather than methods for improving safety. Drivers responding to the NHTSA survey, although indicating support generally for SSC in certain types of locations or conditions, were also more likely to somewhat agree or strongly agree with the statement that speed cameras are used to generate revenue (70%) than with the statement that speed cameras are used to prevent accidents (55%) (Schroeder et al., 2013). Such concerns should be carefully and openly addressed through program design, vendor selection, payment agreements and more. As mentioned above, program oversight and site selection should be handled by public safety agencies (NHTSA & FHWA, 2023). See more information in the updated Speed Safety Camera Planning and Operations Guide, which includes several case studies on garnering and maintaining public and policy approval.
  • Legality: State courts have consistently supported the constitutionality of automated enforcement, although programs should have authorizing legislation in place to ensure compliance with State and local ordinances (Poole et al., 2017). Programs operating without explicit statutory authority may be more vulnerable to successful court challenges (Maisel, 2013; Rodier et al., 2007).
  • Covert versus overt enforcement and other program characteristics: NHTSA and FHWA’s operational guidelines document outline other considerations of overt and covert speed enforcement, enforcement threshold, publicity and signing strategies (NHTSA & FHWA, 2023).