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                        Speed Management: A Manual for Local Rural Road Owners


            
            In This Section
        Local and Rural Road Safety Program
                Training, Tools, Guidance and Countermeasures for Locals Practitioners
                Crash Facts
                
                3. IDENTIFYING COUNTERMEASURES
A coordinated approach to managing speeding and reducing speed-related crashes based on engineering, enforcement, and education countermeasures is desirable. When identifying countermeasures, practitioners should consider strategies that will minimize the severity of speed-related crashes. This will depend on location characteristics and the contributing factors of crashes identified from crash data and field reviews. One method to evaluate potential engineering countermeasures, and their ability to reduce crashes, is using Crash Modification Factors (CMF’s). A CMF is a multiplicative factor used to determine the expected change in the number of crashes after implementing a specific countermeasure at a specific site.*(12)* This section provides information on engineering, enforcement, and education countermeasures that can be used to address a speeding issue.

3.1 Engineering

Reducing the speed limit alone generally does not result in lower speeds. Several engineering countermeasures have been identified that can be used to influence driver speed choice, and the following sub-sections describe engineering countermeasures that address speeding. They have been grouped into three categories: traffic control devices, road and street design, and traffic calming on lower-speed roadways. Since design details are not presented, the road owner should seek engineering expertise when selecting countermeasures.

3.1.1 Traffic Control Devices to Reduce Speed

Installing or upgrading signs and pavement markings on an affected roadway can be a cost-effective measure to reduce speeding. Such improvements include advisory speed signs and pavement markings, speed activated signs, and optical speed bars.

**Advisory speeds** are installed with curve warning signs (either on the same sign or as a supplemental plaque) to recommend a safe speed for traversing a horizontal curve. The warrant for when they should be used are prescribed in the Manual on Uniform Traffic Control Devices (MUTCD) (see Section 2C.07)*(13)* and the procedure for setting advisory speeds on curves can be found in *Procedures for Seeting Advisory Speed Limits on Curves*.*(14)*Advisory speed signs have been found to reduce speeds by two to three mph*(15)* (CMF = 0.71-0.87).*(16)*

"alt="Photo. A yellow advisory sign with a black speed advisory of 15 MPH and curve warning. ""

***Advisory speed displayed with curve warning sign.***

A**pavement speed limit marking** displays the posted speed limit on the pavement. It is used to emphasize the speed limit. A **SLOW** curve ahead pavement marking warns the driver of a potentially hazardous curve. This pavement marking is meant to supplement advsiory signs. Because they are exposed to traffic wear, both types of pavement markings require regular maintenance to ensure their continued visibility.

"Photo. A pavement marking of '25 MPH' to encourage speed reduction for an impending curve. "

***Special pavement marking to encourage speed reduction for impending curve.***

A**speed activated sign** is an electronic sign that is connected to a device that measures the speed of approaching vehicles. If the vehicle is exceeding the legal speed limit, then the electronic sign is activated to display the legal speed limit. This may also be accompanied by the word "SLOW" or other appropriate message. A similar device is a **speed feedback sign.** When connected to a speed-measuring device, a speed feedback sign displays the speed at which a vehicle is traveling. The speed-activated sign and the speed feedback sign can be effective in speed transition areas (e.g., entering a school zone or other area characterized by high volumes of non-motorized traffic). If used too frequently, the effectiveness of these signs is diminished. Speed feedback signs were found to reduce speeds between two and 10 mph*(17)* (CMF = 0.54).*(16)*

"Photo. A solar-powered speed feedback sign. The bottom part of the sign is a typical speed limit sign with a speed limit of 30 MPH. Above that is a changeable display that states 'Your speed 28 MPH' The speed changed based on how fast a vehicle is traveling. Above that is a solar panel to power the sign."

***A solar-powered speed feedback sign.***

**Optical speed bars** are used at spot locations or along a corridor to reduce speeding. These are transverse pavement markings across the travel lane or along its edges placed with decreasing spacing in the direction of travel, which makes it appear to drivers that they are traveling faster than their true speed. They are placed in advance of a speed transition zone or other critical location. This treatment should be used sparingly, else it will lose its novelty effect, and should be maintained to ensure its usefulness. Optical speed bars have been found to reduce speeds by an average of two mph. More details can be found in Section 3B.22 of the MUTCD.

"Photo. A rural two-lane road with optical speed bars on the right lane as it approaches a horizontal and vertical curve. The bars are short white lines on either side of the lane and are placed closer together approaching the curve to give the driver the illusion that they are driving faster. "

***Optical speed bars on a rural roadway placed in advance of a horizontal curve.***

3.1.2 Road and Street Designs

There are several modifications to the design of a road or street that can induce speed reductions and have other safety and operational benefits for all road users. These include reduced lane widths, road diet, center island or median, and roundabout. Several of these countermeasures can be implemented on higher-speed roadways.

**Reducing lane width** to as narrow as 10 feet can reduce speeds. This can be accomplished by restriping narrower lanes without reducing pavement width. The remaining space can then be used for non-motorized uses, buffer areas between travel lanes and non-motorized uses,or space for on-street parking. In rural areas, reducing lane width on roadway segments should only be considered on lower-speed roadways in towns or villages. A nationwide study found no increase in crashes or injuries when lanes were narrowed on urban and suburban roadways.*(18)* Speeds may also decrease by one to three mph for each foot that the roadway is narrowed down to 10 feet.*(19)* At two way stop controlled, rural intersections on high-speed two-lane, two-way roadways lane narrowing through the application of rumble strips on outside shoulders and in a painted yellow median island on major road approaches has been found to significantly reduce speeds and resulted in improved safety performance*(20)* (CMF= 0.69).*(21)*

"Photo. A street where lane widths were reduced to provide exclusive space for cyclists. Through a reduction in lane width, the road currently has one on-street parking lane, one travel lane, and one bike lane. "

***The lane width for motor vehicle travel in this community was reduced to provide exclusive space for cyclists.***

A **road diet** is a conversion of an existing street cross section to create space for other uses (e.g., bicycle lanes, sidewalks, turn lanes, or on-street parking). Figure 3 is a before-and-after drawing of a typical road diet. The original road was four lanes with two lanes in each direction.

"Graphic. On the left is a roadway with four 11-foot lanes, two in either direction. On the right is the same roadway with a road diet. There are now two 5-foot bike lanes, two 11-foot travel lanes, and one 12-foot turning lane."

**Figure 3. Road Diet Comparison**.*(22)*

The same road width remains after the road diet, but the number of travel lanes for motor vehicles is reduced providing space for bicycle lanes in each direction. Road diets have the potential to reduce speeds due to the percieved narrowing of the roadway, with the extra pavement used for center turn lanes, parking, bicycle lanes, or other uses. Road diets have also been found to reduce crashes (CMF = 0.47-0.71)*(23,24)*. More detailed information can be found in the *Road Diet Handbook: Setting Trends for Livable Streets*.*(25)*

A **center island or raised median** can be used to create a shift in the travel path. Shifting traffic is an effective way to reduce speeds. A center island or raised median may also be used to narrow the "optical width" of the roadway, which will make the roadway appear narrower, thereby reducing speeds. Medians have been shown to be effective in lowering operating speeds, especially when they create a deflection in the vehicle path at the beginning of the median. However, attention must be given to the design of the deflection to achieve a speed reduction without compromising safety. For this reason center islands and raised medians are typically applied to developed areas- that is in towns or villages- within the rural context. Another positive aspect of installing medians is that pedestrians’ safety is improved by providing a refuge when crossing the street. According to trafficcalming.org installing medians as a measure for narrowing, results in an average speed reduction of 7 percent of the 85th percentile travel speed*(26)* (CMF 0.29).*(27)*

"Photo. A crosswalk with a island or median in the center providing a refuge for pedestrians and a shorter distance to cross."

***A center island or median.***

A **roundabout** is an intersection with a raised island in the middle that vehicles must travel around in a counterclockwise direction. In order to enter the roundabout, a driver must yield to vehicles traveling in the circulatory roadway. Roundabouts have become popular for intersection traffic control due to documented safety (CMF 0.213-0.58)*(28,29)* and operational benefits. Roundabouts can be extremely effective at improving safety by managing speeds. According to the FHWA’s Proven Safety Countermeasures website, converting a two-way stop controlled intersection to a roundabout can reduce severe crashes by 82 percent and overall crashes by 44 percent. Similarly, converting a signalized intersection to roundabout conversion can reduce severe crashes by 78 percent and overall crashes by 48 percent. For more information concerning roundabouts, refer to FHWA’s Web site on roundabouts at: http://safety.fhwa.dot.gov/provencountermeasures/fhwa_sa_12_005.htm.

"Photo. A rural two lane road leading to a roundabout. "

***A rural roundabout.***

3.1.3 Traffic Calming

Traffic calming is the design or retrofit of a roadway to encourage uniform vehicle speeds and improve conditions for non-motorized users. Traffic calming tends to be applied to roads with operating speeds of 30 mph or less, as these roads are typically developed zones along rural roadways. There are numerous traffic calming countermeasures that can be applied on different types of roads and streets, and these are identified in ITE’s *Traffic Calming: State of the Practice**(30)* and the *FHWA’s Engineering Countermeasures to Reduce Speeds.(31)* Some of the measures that can be applied in rural villages are described in this section.

A**speed hump** is a raised section of asphalt approximately 10 to 14 feet long and 3 to 4 inches high. Speed humps are typically used on lower-speed residential streets in rural areas that are experiencing a high incidence of speeding and/or cut-through traffic.*(32)* Speed humps are not to be confused with speed bumps, which are much shorter and usually found in parking lots. Speed humps have been found to reduce injury crashes by 40 to 50 percent and speeds by nine mph*(33)* (CMF = 0.5-0.6).

"Photo. A speed hump, which is a slightly raised section of roadway that is a couple of feet wide and has a zig zag white pavement marking on top. "

***A speed hump delineated to notify motor vehicles of its presence.***

**Speed tables** are similar to speed humps but have an extended flat section that can accommodate an entire car. This design allows for speeds of 25 to 30 mph, which are typical for local and collector streets. Speed tables are generally placed on roadways where there is minimal heavy truck and farm vehicle traffic.*(34)* Information on the design of speed humps and speed tables are available in ITE’s *Guidelines for the Design and Application of Speed Humps and Speed Tables* (see www.ite.org). According to trafficcalming.org, speed tables have been found to reduce speed by an average of 7.5 mph.*(35)*

"Photo. A speed table, which is a raised of section of roadway – wider than a speed hump. It has a flat section on top that is wide enough to accommodate an entire car. The speed table in the photo is located at a crosswalk. In the photo, a pedestrian is begging to enter the crosswalk, which is signed and has pavement markings but is raised above the roadway."

***A speed table at a pedestrian crossing on a rural road.***

A **mini-roundabout** is smaller than a conventional roundabout and has a mountable center island that is either flush with the pavement or slightly mounded. It is typically installed on roadways with speed limits of 35 mph or lower. This measure can reduce speeds by an average of 10 mph, since traffic is required to yield to road users in the mini-roundabout.*(35)*

"Photo. A rural mini-roundabout. The roundabout consists has one travel lane and a flush concrete circle in the center."

***A mini roundabout.***

A **traffic circle** is intended for low-volume and low-speed roads, such as those in residential areas. A raised center island is constructed in the intersection. Landscaping can be added to the island for aesthetic value but should not obstruct the view of the intersection. A traffic circle is quite different from a roundabout or mini-roundabout, as a yield sign is not mandatory for this intersection. Also, it is permissible to turn left in front of the center island, a maneuver that is prohibited at a conventional roundabout. Traffic circles have been found to reduce speeds by up to 15 mph.*(36)*

"Photo. A traffic circle with a landscaped circle in the center."

***A traffic circle.***

For more information on traffic circles and mini-roundabouts, FHWA has published an informative technical summary on mini-roundabouts that can be found in FHWA’s *Technical Summary: Mini-Roundabouts*or NCHRP 672, *Roundabouts:An Informational Guide.**(37)*

3.1.4 Gateway Treatments

A common speeding-related problem occurs when a driver approaches a rural town or village from a higher-speed rural road. Gateway treatments (also called gateways) can be used in rural areas to capture the attention of drivers and inform them that the nature of the roadway is changing, and, as a result, they should reduce their speed.*(36)* A gateway is a "combination of traditional and nontraditional traffic control treatments, such as enhanced signing, lane reduction, colored pavements, pavement markings, experimental striping, gateway structures, and traditional traffic calming techniques or other identifiable features."*(38)* A key consideration is the proper use of transitional speed limits and the Reduced Speed Limit Ahead warning signs as prescribed in the MUTCD (see section 2C.38).

"Photo. A gateway treatement or a landscaped island entering a rural community. "

***A gateway treatment entering a rural community***

The gateway needs to be conspicuous to be effective. It is also important to ensure that devices used as part of a gateway treatment (1) are crashworthy if placed within the clear zone and (2) do not obstruct sight distance, as gateways placed in the roadway may become fixed object hazards. Gateways have been found to reduce speeds by an average of five mph.

Additional information on the effectiveness of engineering countermeasures is available in the FHWA publication *Engineering Countermeasures for Reducing Speeds.(39)*

3.2 Enforcement

Enforcement is critical in some locations to achieve compliance with posted speed limits. According to the *Uniform Guidelines for State Highway Safety Programs*, more than half of all traffic stops result from speeding violations, and public support for speed enforcement activities depends on the confidence of the public that the speed enforcement is fair, rational, and motivated by safety concerns.*(40)*

Speed enforcement that is perceived predominantly as a means to generate revenue will be met within difference, at a minimum, and active resistance, at worst, from the motoring public. Speed enforcement countermeasures should primarily be at times and locations that can be directly tied to speeding-related crashes and areas of excessive speeding.

Traffic enforcement seeks to generate deterrent effects on speeding that are both specific and general. The specific deterrence is based on the idea that individual drivers who are caught and punished for speeding will be dissuaded from committing further speeding violations in the future. The general deterrence is based on the assumption that the process of apprehending individual violators can influence the behavior of a larger segment of the driving population.

There is an established linkage between speed education efforts and speed enforcement initiatives. Working together, these strategies amplify the impact of each element’s contribution to traffic safety. NHTSA’s high-visibility model recommends using a strategic combination of public information, education, and targeted speed enforcement at times and locations where excessive speeding and speeding-related crashes have been documented.*(41)* These efforts are often conducted periodically and last from one to several weeks so that coordinated speed enforcement can take place among multiple law enforcement agencies on a consistent basis.

In many rural areas, individual traffic officers may be responsible for patrolling large areas. Rural law enforcement agencies often do not have resources available to respond to each traffic safety issue identified within their jurisdiction.

It is important that the engineering and law enforcement disciplines form a partnership to address speeding. Regular meetings between engineers and law enforcement officers responsible for traffic enforcement should be scheduled to discuss speeding concerns. Traffic engineers and law enforcement agencies must work closely together to identify roadway locations where engineering countermeasures alone will not address speeding, financial resources are not available to implement robust engineering measures, and speed enforcement strategies are needed.

The relationship between the engineering and enforcement communities will be beneficial to the Speed Management Program through the sharing of knowledge. For example, the engineering community can explain the process of setting speed limits to the police officers charged with enforcing them, and the enforcement community can discuss the need for and the optimal configuration of emergency pull-off areas to the individuals who are responsible for designing the roadway environment. Other community stakeholders (e.g., from schools, emergency services, hospitals, etc.) may also be invited to participate on a regular or as-needed basis. The Mississippi Demonstration Project, detailed on the following page, is an example of a successful partnership between engineers and local law enforcement personnel that was effective in educating the driving population.*(42)*

**In 2001, NHTSA, FHWA, and the Mississippi DOT teamed up with the Cities of Gulfport and Southaven to carry out an assessment of setting rational speed limits, enforcing those limits, and educating the public on speeding-related issues. Gulfport used the engineering process of setting speed limits to the 85th percentile, as well as strict enforcement and plenty of public education. Southaven was monitored, as well, although there were no changes in the speed limits, enforcement, or public education. Improvements were noted in Gulfport in drivers’ compliance with the newly-introduced rational speed limits (based on the 85th percentile) as compared to Southaven, which kept the same speed limits as before.**

3.2.1 Traditional Enforcement

The primary speed enforcement tools used by law enforcement patrol officers include RADAR (RAdio Detection And Ranging), LIDAR (LIght Detection And Ranging), and vehicle pacing. With proper training, these tools constitute effective means to identify and cite speeding violators. Due to the ease of use, accuracy, and steadily decreasing costs, RADAR and LIDAR (or laser) instruments have become the preferred method of speed detection by law enforcement. In some States, grants are available from organizations such as the GHSO to purchase or upgrade RADAR and/or LIDAR equipment.

For speed enforcement deployments, rural law enforcement agencies often make greater use of "moving" RADAR equipment (RADAR that can capture the speed of traffic when the patrol vehicle is moving). The size of a typical rural patrol area often requires officers to patrol for speeders in moving mode to allow them to canvas the large geographic areas assigned to them over the course of a work shift. In general, rural and suburban patrol officers are also more likely to work individually on speed enforcement compared to their urban counterparts. Often, when a new Speed Management Program is being unveiled, rural or suburban agencies will combine resources. Officers from several agencies within the same jurisdictional authority (e.g., village, township, county, and/or State agencies) will agree to work together to address specifically-identified stretches of a roadway where speeding and crashes are clearly a problem. These collaborative traffic safety efforts by law enforcement agencies are a means to maximize the impact of scarce resources and heighten awareness of speeding issues experienced by the motoring public. NHTSA provides each State’s GHSO with Federal funds that can be used to target specific traffic safety issues—and speeding is being increasingly identified as a priority.

3.2.2 Automated Enforcement

Automated Speed Enforcement (ASE) systems are also effective methods to prevent speeding-related crashes. ASE combines RADAR or LIDAR with sophisticated digital camera systems and computer technology to detect speeding violations and record identifying information about the vehicle and/or driver. ASE is a supplement to traditional speed enforcement countermeasures.

"Photo.  A photo showing the equipment inside an automated speed enforcement van."

***The equipment within an automated speed enforcement van***.

By utilizing ASE, an agency will be able to do the following:

Conduct speed enforcement in areas where traditional traffic stops are dangerous or infeasible due to the roadway design.
	Continuously conduct speed enforcement on roadways identified as high-crash locations where traditional law enforcement is not practical.
	Reduce the impacts of driver distraction and congestion that often result during traditional traffic stops made by law enforcement, especially during peak travel periods.Agencies should check for ASE laws or regulations within their State when considering the implementation of ASE. Communities considering ASE as an option should review the *USDOT Speed Enforcement Camera Systems Operational Guidelines* (March 2008) for information on implementing and operating an ASE program.*(43)*

*3.2.3 Vehicle Pacing*

Officers in some jurisdictions may also use pacing. Pacing is an enforcement method in which the officer observes traffic speeds from a moving vehicle and then pursues a violator.*(44)* To apply this method, a police vehicle's speed is matched to that of a target vehicle, and the calibrated speedometer of the patrol car is used to infer the other vehicle's speed. Pacing can be an effective, more convenient alternative method of identifying a vehicle’s speed if a more convenient if a speed-measuring device is not available.

3.3 Education

Citizen concerns and behavior often drive speed management policies and any associated education efforts. A comprehensive Speed Management Program attempts to address these concerns and behaviors through a data-driven approach.

NHTSA has developed a Speed Campaign Toolkit for public information and education outreach that has been tested and validated in programs across the United States.*(45)* This toolkit provides example marketing materials that can be used or distributed to fit local needs and objectives while partnering with other local or national communities and organizations on developing a speed management strategy. More information on the toolkit can be found at http://www.trafficsafetymarketing.gov.

NHTSA advises that traffic safety education campaigns should include participation from stakeholders representing law enforcement, engineering, public health, the judiciary, and prosecutors to ensure that agencies directly impacted by enforcement countermeasures are "in the loop" and have input into the proposed effort.*(46)* This also includes private partners, such as hospitals, news organizations (newspaper, radio, and/or TV), major employers, and local businesses.
      
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                Book:Speed Management: A Manual for Local Rural Road Owners
              1. Introduction
                2. IDENTIFY SPEEDING ISSUES
                3. IDENTIFYING COUNTERMEASURES
                4. IMPLEMENTING COUNTERMEASURES
                5. SUMMARY
                References U.S. DEPARTMENT OF TRANSPORTATION

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