Transportation Review | Speeding and Speed Limits

Amanda Essex, Douglas Shinkle and Anne Teigen 2/16/2017


In 2014, 9,262 traffic fatalities occurred in speeding-related crashes. The National Highway Traffic Safety Administration (NHTSA) considers a crash to be speeding-related if the driver was charged with a speeding-related offense or if an officer indicated that racing, driving too fast for conditions or exceeding the posted speed limit was a contributing factor in the crash. The number of fatalities in 2014 represented a 3.65 percent decrease from 9,613 in 2013. The most recent year for which statistics are available—2014—saw the fewest speeding-related fatalities in the last 10 years, with a peak of 13,609 fatalities in 2006. While the number of speeding-related fatalities have decreased in recent years, speeding still was a factor in 28.3 percent of motor vehicle fatalities in 2014.

slow lane speed limitCitizen attitudes often tend to reflect an acceptance of speeding as a social norm, despite its inherent dangers and the fact that it is the cause of thousands of crashes each year. According to AAA’s 2014 Traffic Safety Culture Index, 46.1 percent of drivers say they have driven 15 mph over the speed limit on a freeway in the past month, and more than 20 percent say it is acceptable to do so. Slightly fewer drivers (43.5 percent) have gone 10 mph over the limit on a residential street in the past month, but 90.2 percent of drivers surveyed say they disapprove of speeding on a residential street.

This report examines trends in speed-related state legislation from the 2013, 2014 and 2015 state legislative sessions. Particular areas analyzed include:

  • Raising speed limits
  • Lowering speed limits
  • Work zones
  • Automated speed enforcement
  • State or local control
  • Penalties for speeding
  • Limiting revenues from speeding citations
  • Keep Right (Slowpoke) laws


In 1995, Congress repealed the maximum speed limit of 65 mph. A limit of 55 mph had been established in 1974, and the limit was increased to 65 mph on certain interstate highways in 1987. Following the repeal of the National Maximum Speed Law, states were given more power to set maximum speed limits. Since then, 38 states have set speed limits of 70 mph or higher on some portion of their roadway systems.

With the elimination of a national maximum speed limit, states needed a way to calculate the appropriate maximum speed limit for their roads. When setting speed limits, states generally set the limit at or near the 85th percentile speed, meaning the speed at or below which 85 percent of operators drive in normal conditions. This percentile approach was originally based on considerations related to safety, with research indicating that “traveling at or around one standard deviation above the mean operating speed…approximately the 85th percentile speed) yields the lowest crash risk for drivers.”

Critics of the approach cite the fact that basing the speed on the behavior of drivers “assumes that motorists are aware of and select the safest speed” and point to the fact that “drivers are generally bad at accounting for the externalities of their driving.” While this is the method generally used by states, a report from the Federal Highway Administration (FHWA) indicates that “there has been no consensus among practitioners concerning the methods and techniques that should be used to select the most appropriate speed limit for a particular facility” and consensus does not appear likely in the near future. According to the recent Innovative DOT handbook produced by the State Smart Transportation Initiative and Smart Growth America, some states—such as Florida, Massachusetts, New Jersey and Pennsylvania—have taken steps to revise their roadway design process to include more local flexibility, the use of context-based design standards and speeds, and more use of traffic calming measures, among others.

According to FHWA, “while the laws of physics make it very clear that speed and crash severity are inextricably linked…there has been a good deal of controversy over the impact of speed on crash occurrence.” Although there is controversy regarding whether higher speeds contribute to increased numbers of crashes, FHWA concluded, based on a 2004 study, that “the most recent and statistically robust research on speed and crash occurrence fairly definitively indicates that, all other factors being equal, increased speeds increase crash occurrence.”

One significant factor that has been identified in connection with speed is the age and gender of the driver. In its Traffic Safety Facts on speeding using 2013 data, NHTSA found that “about 35 percent of 15-to-20-year-old and 21-to 24-year-old male drivers involved in fatal crashes were speeding,” the highest among all age groups and much higher than the 21 percent for females in those age groups involved in fatal crashes. In addition, the 2011 National Survey of Speeding Attitudes and Behavior found that younger drivers were more likely to be speeders; 50 percent of 16- to 20-year-old drivers were classified as speeders compared to 15 percent of drivers over age 65. With respect to gender, in every age category within the 2013 data, males comprised a higher percentage of speeding drivers in fatal crashes than females. Similarly, the 2011 survey found that 36 percent of male respondents were classified as speeders compared to 28 percent of female respondents.

Another significant factor in speed-related crashes is alcohol; 42 percent of speeding drivers in fatal crashes had blood alcohol concentrations over the legal limit, compared to 16 percent of non-speeding drivers, according to NHTSA’s 2013 data. “For every age group…drivers involved in fatal crashes in 2013 who were speeding were alcohol-impaired more than twice as often as those not speeding.” 

When considering the types of vehicles involved in speed-related fatal crashes, NHTSA found that 34 percent of motorcycle riders in fatal crashes were speeding, which was the greatest percentage of any vehicle type. Twenty-one percent of passenger car drivers in fatal accidents were speeding, as were 18 percent of light-truck drivers and 8 percent of large-truck drivers. 

The occurrence of speeding also varies by region. In the 2011 survey, speeding drivers were more prevalent in the western part of the United States, while the Pacific Northwest, Midwest and Southeast had the lowest percentages of speeders. A study from the University of Michigan Transportation Institute, summarized by CityLab, found that car deaths are “lower in denser, more urbanized states” where people tend to drive less and more slowly than in less populous, more rural states. “The states with the highest rate of road deaths all have top speed limits of at least 70 mph and some have top limits of 80 mph.”

One study from 2007 found that higher speed limits (up from 65 mph to 70 mph) on interstate highways in Indiana did not significantly affect the severity of injuries in accidents, but higher speed limits on non-interstate highways “are associated with a greater likelihood of injury and/or fatality on some (but not all) roadway types (county, state, city and U.S. routes) and accident types (single and two-vehicle).” The study also determined that the results could not necessarily be extrapolated to speeds over 70 mph and that “there is likely a point beyond which higher speed limits will significantly increase the severity of accidents on interstates.”

Areas of State Action

State Speed Limit Legislation 2013-2015In response to the impact of speed limits and speeding on road safety, states continue to consistently debate legislation on this topic. In 2015, 43 states considered 114 bills related to speed limits, of which 19 were enacted. In 2014, 37 states considered 80 bills and 15 were enacted. In 2013, 35 states considered 88 bills and 17 were enacted. 

In states that are considering legislation in the area of speeding and speed limits, several types of action could be taken. Some states have raised speed limits in recent years, while others have lowered them. A number of states have taken action related to specific speed zones, whether they be school zones, work zones or other types. Some state policies provide more flexibility for localities to set their own speed limits. States have modified penalties and limited the amount of revenues from traffic violations. All states have a slowpoke law that requires slow drivers to move out of the left lane of traffic.

Raising Speed Limits

speed limit signOne of the most significant areas of state speed legislation in recent years has been raising speed limits. Studies have shown that increasing the speed limit does not necessarily lead to an equivalent increase in driving speed because drivers continue to drive at the rate of speed at which they feel comfortable. Particularly, according to a National Cooperative Highway Research Program study, “A speed limit increase on a high-speed road is generally associated with a less-than-equivalent increase in average vehicle speed: a 10-mph speed limit increase, for example, corresponds to average speeds around 3 mph higher.” An increase in speed limits may be an adjustment to match the speed at which people already are driving. The sponsor of Montana’s enacted 2015 legislation, Senator Scott Sales, expressed in a hearing on the bill that he hoped the legislation would save people time and money.

A few states have recently increased their maximum speed limits to 80 mph. In 2015, Montana, Nevada, South Dakota and Wyoming increased the maximum speed to 80 mph; Montana also increased the maximum speed limit for trucks to 65 mph. Utah passed legislation in 2013 allowing the state DOT to increase speed limits to 80 mph on certain parts of state highways.

Other states have increased speed limits to 75 mph. In 2015, Washington did so. Maine passed legislation in 2013 allowing speeds of up 75 mph on the interstate system and other divided controlled-access highways. Florida passed legislation in 2014 that would have raised the speed limit on state highways by 5 mph under certain conditions, up to 75 mph on limited access highways, but the legislation was vetoed by the governor. In his vetomessage, Governor Rick Scott said, “Although the bill does not mandate higher speed limits, allowing for the possibility of faster driving on Florida’s roads and highways could ultimately and unacceptably increase the risk of serious accidents for Florida citizens and visitors…”

A handful of other states have raised their speed limits to 70 mph as well. In 2015, Wisconsin increased the maximum speed limit to 70 mph, while Maryland and Oregon increased the speed limit on certain stretches to 70 mph. An Illinois bill in 2014 to increase speed limits on toll roads to 70 mph was vetoed by the governor, but that veto was overridden. In his veto message, Governor Pat Quinn stated that “the convenience of increased speeds for drivers on Illinois tollways does not outweigh the safety risks to children, families, and our dedicated public servants.” This proposed increase on toll roads was in addition to a 2013 increase on certain interstate highways from 65 mph to 70 mph. On a section of I-93 in New Hampshire, the limit was increased from 60 mph to 70 mph, and Ohio raised the speed limit to 70 mph on freeways outside of urban areas.

Laws were passed in Idaho, Utah and Wyoming in 2014 to allow an increase in speed limits in specific circumstances. In Idaho, the speed limit can be increased to 80 mph on interstate highways and to 65 mph on state highways if the DOT completes an engineering and traffic study and concludes the increase is in the public interest. Before the speed limit can go into effect, the transportation board, which supervises the DOT, must concur with the DOT’s conclusions. In the last three years, six other states—Connecticut, Iowa, Kansas, Mississippi, Missouri and New York—also considered legislation to raise speed limits, although those efforts were unsuccessful.

School Zones

  • School zones are a special speed zone in which a lower speed limit is in place based on a road’s or area’s proximity to a school.
  • A number of states have introduced legislation related to school zones in recent years, although few of these bills have been enacted.
  • In 2015, seven states—California, Illinois, Michigan, Rhode Island, Texas, Vermont and Virginia—considered bills related to school zones. Illinois passed a bill specifying that a driver exceeding a certain speed in a school zone is not eligible for supervision rather than incarceration.
  • School zone speed legislation was considered but not enacted in Mississippi, New York, Ohio, Oklahoma and West Virginia in 2014.

Lowering Speed Limits

slow signWhile the broader trend has been to increase speed limits, a number of states are making legislative efforts to give municipalities authority to reduce speed limits in busy residential and business districts where there are many pedestrians and other vulnerable users. A small reduction in speed can mean the difference between life and death for pedestrians. A 2011 AAA study examined impact speeds and the commensurate risk of injury or death for a pedestrian; small changes in speed can lead to much higher risk of death. The study notes that the “average risk of death for a pedestrian reaches 10 percent at an impact speed of 23 mph, 25 percent at 32 mph and 50 percent at 42 mph.”

Roadway speeds also can have serious implications for bicyclists. For a two-year period, the League of American Bicyclists attempted to track and analyze every bicyclist fatality in the United States in order to glean better insight into what caused the fatalities. According to the analysis, nearly half, 44 percent, of fatalities occurred on high-speed urban arterial roads where there tend to be fewer bicycle facilities. As a recent study from Texas A&M University pointed out, “While high design speeds are viewed as desirable for motorist safety, they are not safe for pedestrians and bicyclists.”

States are acknowledging the needs of local communities that want to emphasize safe roadway environments for pedestrians, bicyclists, school children, people with disabilities and others. In the past few years, several states have given localities the ability to reduce their minimum speeds in order to create a safer travel environment for vulnerable users. 

In the Pacific Northwest, both the Oregon and Washington legislatures have recently acted to make it easier for municipalities to reduce speed limits in specified instances. In 2011, the Oregon legislature enacted legislation allowing speed limits of 20 mph, rather than 25 mph. The road authority must confirm that the streets have a traffic volume of fewer than 2,000 motor vehicles per day, with more than 85 percent traveling less than 30 miles per hour, and certain signage requirements must be met, including those to indicate the presence of bicyclists and pedestrians.

The Washington Legislature followed suit in 2013 with a law allowing municipalities to establish a maximum speed limit of 20 mph in a residential or business district. Previously, municipalities were required to undertake time-consuming and expensive studies before they could lower speed limits. The new law however, stipulates that a reduced speed need not be based on any traffic or engineering study. The law also allows a municipality to reinstate the former speed limit within a year of its change without a traffic or engineering study.

Thus far, both Portland and Seattle have taken advantage of the recent law changes to lower speed limits on their neighborhood greenways, which are residential streets that prioritize travel by bike and foot and often include other traffic-calming attributes. Portland has created a 70-mile network of neighborhood greenways where street speed limits are set at 20 mph. According to the latest numbers from the U.S. Census’ American Community Survey, Portland and Seattle are first and fifth, respectively, for the highest rates of bicycle commuters in large American cities.

New York City, which has launched a high-profile Vision Zero initiative to reduce traffic fatalities to zero in the city, took advantage of 2014 New York state legislation to reduce the citywide speed limit to 25 mph. While some streets may have higher or lower speed limits, the de facto speed limit is 25 mph when a specific limit is not posted.

In 2015, a number of states enacted legislation allowing speed limits to be lowered in certain instances. The Indiana legislature enacted a law allowing a locality that is not an urban district to establish a school zone speed limit of 20 mph. Previously, a town or county that was not defined as an urban district was not allowed to enact a speed limit lower than 30 mph. New Hampshire enacted legislation allowing a municipality to petition the state Department of Transportation to create a reduced seasonal speed limit to increase safety conditions on roads that are seasonally congested with pedestrian and bicycle traffic. If the state DOT agrees, the speed limit can be no lower than 20 mph and cannot extend for longer than four months total a year; the municipality is responsible for signage costs.

New Mexico passed a law changing the maximum speed on county roads without a posted speed limit to 55 mph rather than the previous 75 mph. South Dakota authorized townships to establish speed zones on their roads, although no speeds may exceed 55 mph. Four other states—Kansas, Missouri, Ohio and Texas—considered, but did not enact bills in 2015 that would have reduced speed limits.

Speed Calming Infrastructure

Studies have been conducted to evaluate the effectiveness of speed bumps in reducing vehicle speeds and crashes.

  • One study found that the average speed reduction resulting from use of speed bumps on a street was 7.2 mph, from 34.0 to 26.8 mph. This study also found that streets with speed bumps experienced a 39 percent decrease in crashes per year.
  • A report from the Iowa Department of Transportation found that the extent of speed reduction depends upon several factors, among them design and spacing, the surrounding environment and vehicle mix.
  • Pending New York legislation would require establishment of a process to determine the need for traffic control signals at intersections within New York City, with consideration of other traffic control techniques—such as speed bumps—as one alternative to traffic signals.
  • Roundabouts are another infrastructure option used to reduce speed and speed-related crashes; studies typically find they reduce severe crashes, in part because their design forces motorists to slow to speeds of 15 mph to 25 mph and because they mostly eliminate the potential for head-on and t-bone collisions.
  • The Wisconsin Legislature debated pending legislation that would have disallowed roundabout construction as part of a highway project unless the authority in charge of the highway project obtained approval for the roundabout from the municipality where the proposed roundabout would be located.

Work Zones

construction zoneWork zones are one of the special speed zones that have seen a fair amount of legislation in the last few years. According to FHWA, “the combination of more work done alongside increasingly heavier traffic and greater use of night work can result in increased safety considerations for highway workers.” FHWA provides a number of resources about good  practices to help keep workers safe, and several states also have introduced legislation to increase protection.

In 2015, Illinois enacted a law specifying that a driver exceeding a certain speed in a work zone was not eligible for supervised probation, instead being subject to incarceration. Minnesota passed a law in 2014 that fines motorists $300 for speeding in work zones. Hawaii, Michigan, North Carolina, South Carolina and Texas also recently considered legislation related to work zones. South Carolina’s 2014 bill would have created the offense of “endangerment of a highway worker,” carrying a penalty of between $500 and $1,000 and 30 days in jail. The penalty would have doubled if a highway worker was injured in the incident.

Automated Speed Enforcement

Automated speed enforcement (ASE) enables local law enforcement agencies to enforce traffic laws remotely. Photo radar systems are deployed using a number of techniques, including fixed positions that are mounted on poles or other structures and mobile systems mounted in a vehicle, such as a van. ASE systems employ speed measuring devices (RADAR or LIDAR) that are linked with cameras that capture violations; these are later processed and a citation is issued to the vehicle owner. Each community sets an enforcement threshold, based on a variety of factors. Thresholds often are set at 11 mph or 12 mph over the posted speed limit.

Approximately 140 communities nationwide have speed camera programs. State legislation addresses automated enforcement using various approaches. Arkansas, New Jersey and Wisconsin laws prohibit the use of ASE. By comparison, Colorado, for example, authorizes automated enforcement for any traffic violation, including speed. Laws in the remaining states either limit ASE use or define how it can be used, or have no laws that address the subject. Communities in Alabama, Arizona, Colorado, Illinois, Iowa, Louisiana, Maryland, Missouri, New Mexico, New York, Ohio, Oregon, Tennessee and Washington and the District of Columbia use speed cameras. Maryland, Oregon and Washington have statewide speed camera programs in work zones.

Although Iowa and Ohio do not have specific statutes, cameras are used in certain cities.  In 2015, Oregon expanded its photo radar program in Portland. Now, a system can be operated in highway segments that have a high number of crashes that result in serious injuries or fatalities. At its own cost, the city of Portland may put speed cameras in these “urban high crash corridors” if a sign is posted alerting drivers of their current rate of speed and that photo enforcement is in use. Photo enforcement systems also must remain in the same location for 180 days.

In 2013, Arizona enacted legislation requiring cities and towns that wish to deploy ASE on state highways to provide proof to the Department of Transportation that the photo enforcement system is necessary for public safety in the state and to obtain a permit or enter into a contract with the department for use of the right-of-way. The permitting process must include speed studies and an analysis of crash reports in the proposed enforcement area. Permits may be issued to municipalities for a maximum of three years, and the DOT must review and compare crash and speed data before and after automated enforcement. It may deny renewal if the department determines that the photo enforcement system does not maintain a positive impact on public safety.

In contrast, Tennessee passed legislation in 2015 to limit the permitted use of unmanned traffic enforcement cameras to marked school zones or on any S-curve of a public road or highway “that inhibits a driver’s full vision through the bend.” Some states—including Arkansas, New Jersey, Texas and Wisconsin— have passed laws that completely prohibit law enforcement use of photo radar. Automated enforcement continues to be a contentious issue in many states.

State or Local Control

speed overviewAnother topic that has seen a significant amount of legislation involves states providing localities more leeway to set speed limits. Generally, state departments of transportation are responsible for setting speed limits, following studies to determine the appropriate speed for a certain stretch of road. However, legislation considered in the last few years has provided localities with more authority to modify speed limits. 

In 2015, South Dakota passed a bill allowing township boards to establish speed zones on township roads, perhaps setting lower limits than those set by the state. Similar legislation also was considered in Alabama, Arizona, Mississippi, Montana, New York and Pennsylvania in 2015. In 2013 and 2014, Colorado, Illinois, New York, Texas and Washington enacted laws extending local authority. Colorado’s legislation allowed the DOT to consider data provided by a local government that would be affected by a proposed speed limit modification. Illinois specified counties that could opt out of increased speed limits.

While a handful of states have passed legislation expanding local control of speed limits, legislation also has been enacted to limit this control. Virginia passed legislation in 2015 specifying that counties could increase or decrease the speed limit only after an engineering and traffic study showed that such a modification was appropriate. The law also specifies that the new speed limit will not be effective unless it is conspicuously posted. In 2014, Delaware passed a law specifying that the DOT must approve changes to absolute speed limits made by local authorities on state-maintained highways. Virginia expanded a maximum 35 mph speed limit for travel on dirt and gravel roads to apply to the entire state, rather than requiring it only in certain counties.

Penalties for Speeding

TrooperA few states have passed legislation to modify the penalties assessed for speeding. Montana’s 2015 legislation not only increased the maximum speed limits, but also increased the fines for speeding, which are lower than those in most surrounding states. The Montana legislation increased the fine for exceeding the speed limit by 11 mph to 20 mph from $40 to $70; from $70 to $120 for 21 mph to 30 mph over the speed limit; and doubled it to $200 for going more than 31 mph over the speed limit. No modifications were made to the fine for up to 10 mph over the speed limit.

In 2013, the District of Columbia enacted legislation requiring the mayor to consider the potential safety impacts of lower fines. In 2015, Illinois considered multiple bills to modify penalties, including one that would eliminate the requirement of a court appearance for violating the speed limit in a construction zone, one that gives the court discretion to determine if a violation of 26 mph or 35 mph over the speed limit is a serious traffic violation, and a third that would allow suspension of a driver’s license in certain cases. Arizona also considered legislation related to penalties in 2015.

Limiting Revenues from Speeding Citations

A handful of states place limits on the amount of revenue that cities or towns can collect from traffic citations, including speeding tickets. A Georgia statute specifies that it is presumed that speed detection devices are being used for improper purposes by a law enforcement agency if the fines levied by those devices are equal to or greater than 40 percent of the agency’s budget. New York, Oklahoma and Texas also have similar laws.

Florida passed legislation in 2015 that requires a county or municipality to submit a report to the Legislative Auditing Committee if the total revenue from traffic citations exceeds 33 percent of the expenses to operate the law enforcement agency in the same fiscal year. Missouri considered legislation in 2013 to require that revenues from all traffic violations over 20 percent of operating expenses be sent to the Department of Revenue to give to schools. In 2015, Missouri enacted a bill implementing this limit, with the threshold being reduced even further to 10 percent, beginning in 2017. This change was sparked in part by scrutiny over traffic revenue collections in Ferguson, Mo., after the protests there.

Keep Right (Slowpoke Laws)

All states have laws requiring vehicles traveling slower than the normal speed of traffic to operate in the furthest right-hand lane available. A number of states specify a penalty for drivers who fail to move out of the passing lane, thereby disrupting the flow of traffic. In California, the base fine for a violation is $35. In Colorado, the penalty is $100. Kentucky provides a penalty range between $20 and $100.

Relatively little legislative action has occurred on this topic recently, but in 2014 Georgia modified its law to expand the number of exceptions, including when traffic conditions, inclement weather, obstructions or hazards make it necessary to drive in the passing lane, as well as when exiting or turning left or when necessary to pay a toll.

Autonomous Vehicles

autonomous VehicleWith advancements in autonomous vehicles growing by leaps and bounds, a future with semi-autonomous or fully autonomous vehicles operating on public roadways is perhaps not too far away. This will create many interesting questions.

  • For example, autonomous vehicles will likely be programmed to not exceed the posted speed limit in any given area, thereby theoretically not only reducing the dangers of vehicles traveling at different rates of speed, but also limiting the revenue from speeding infractions.
  • In addition, human error will be largely removed from the equation when all vehicles on the road are autonomous and there is fully integrated vehicle-to-vehicle and vehicle-to-infrastructure technology.
  • It is difficult to predict precisely the influence of autonomous vehicles on speed limits and traffic safety in general, although it is safe to say that there certainly will be some type of impact.