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News Release

news release

18 Month Study Report on
65 MPH Speed Limit in New Jersey

I. Introduction

In 1995, the United States Congress repealed the National Maximum Speed Limit of 55 MPH (in effect since 1974 when it was started as a fuel-saving measure) and returned to the states the responsibility for setting speed limits on major highways. While Congress allowed states to increase speed limits on rural interstates to 65 MPH in 1987, New Jersey did not change the 55 MPH speed limit, as very little mileage qualified as rural interstate. The federal government lifted the rural interstate restrictions in 1995.

In late 1997, the New Jersey Legislature acted to raise the 55 MPH speed limit to 65 MPH on portions of the state highway system, including but not limited to, interstate highways and highways of similar design and access control. The legislation also established the 65 MPH speed limit as prima facie on the New Jersey Turnpike, the Garden State Parkway and the Atlantic City Expressway. Through negotiations, the Legislature and the Administration agreed to an 18-month Study test period on "approximately 400 miles" of highway statewide. The new law, approved January 19, 1998, gave the Department of Transportation (DOT), in consultation with the Attorney General and the toll authorities, four months to establish the designated network, and the DOT the lead in implementing the 65 MPH Speed Limit for the 18-month Study period. The list of these designated roadway segments is detailed in Appendix A.

An integral enforcement aspect of the new law was inclusion of safety-related traffic offenses, such as reckless driving, changing lanes without signaling, and speeding at 10 miles per hour or more over the 65 MPH limit, for which the fines were doubled if committed in the 65 MPH zone. The list included what are often characterized as aggressive driving offenses. Fines were also doubled for offenses committed while speeding at 20 miles per hour or more in the non-65 MPH zones. While the maximum speed limit was increased, a more stringent enforcement regimen was established to deter excessive speed and other unsafe driving practices.

On May 19, 1998, the Commissioner of Transportation designated 475.49 miles of roadway for a 65 MPH Speed Limit in New Jersey, pursuant to Public Law 1997, Chapter 415, for a study period of 18 months. At the end of this study period, the Department of Transportation, through a statewide task force, had three months to submit a study to the Governor and the Legislature. The legislation provides that the Commissioner of Transportation, in consultation with the Attorney General and the New Jersey Turnpike Authority (NJTA), the New Jersey Highway Authority (NJHA), and the South Jersey Transportation Authority (SJTA), shall recommend speed limit modifications, and whether 65 MPH roadway mileage should be increased, decreased or stay the same.

During the 18-month study period following implementation of the 65 MPH, the statewide task force (consisting of representatives from NJDOT, NJTPA, NJHA, SJTA and the New Jersey State Police) looked at overall impacts on factors such as public safety, environmental and cost issues, speed, accident rates, fatalities, enforcement, and air quality.

II. Initiation of New Maximum Speed Limit

A. Establishment of Task Force
A Task Force was established of representatives within the DOT to develop an Implementation Plan, and an 18-month Study Plan. Representatives include the following divisions/bureaus: Traffic Engineering and Safety Programs, Operations, Capital Program Management/Design Services, Division of Transportation Systems Planning, Transportation Data Development, Legislative Analysis, Motor Vehicles, Communications and Deputy Attorney General for DOT. Representatives of other non-DOT agencies include: Toll Authorities, State Police, Highway Safety, Attorney General, and Administrative Office of the Courts. The Task Force met throughout the study period.

B. Selection of Roadways for 65 MPH
To determine the approximately 400 miles of roadway segments to be posted at 65 MPH, the Task Force used criteria that would help identify for the public the different environments between 55 MPH and 65 MPH. The roadway segments selected for 65 MPH were based on the following criteria:

Segments must be at least 10 miles in length - This is an informal national standard intended to prevent driver confusion from seeing too much variance in posted speed limits on the same roadway. This eliminates the short freeway segments on State Routes including: Rtes 1, 3, 4, 15, 21, 24, 29, 33, 42, 440, and 495.

Spacing of access ramps must not be too short - When there are closely spaced ramps, it leads to significant roadside friction, with all the weaving and merging movements occurring, making travel at higher speeds less safe. This tends to be common in the inner urban areas.

Roadway Segment must be designed for 65 MPH - This tends to be a problem in the inner urban areas with significant developments and high population densities. In order to accommodate the heavier traffic volumes, design characteristics of the roadway may not be favorable to higher speeds. These design characteristics include acceleration and deceleration lanes to and from low speed ramps, vertical curves crossing over surface streets, narrow shoulder widths, etc. Again this tends to be most common in the inner urban areas.

Roadway Segment must not experience significant recurring congestion - Roads that experience significant congestion over several hours of the day, create an environment that can be unsafe for higher speeds. Although these roads may experience light traffic at late night and early morning hours, the periods of congestion experience significant weaving and higher numbers of accidents.

In summary, the roadway segments selected for the 65 MPH Speed Limit tended to be in rural and suburban settings, while the 55 MPH Speed Limit remained in the more urban areas.
C. Initiation of 65 MPH Speed Limit
The Task Force identified necessary signing and safety measures to implement the 65 MPH speed limit. Where appropriate, this included change of 55 MPH Speed Limit signs to 65 MPH speed limit signs, installation of AReduce Speed Ahead@ signs at the end of the 65 mph zones, and "fines doubled@ signs at intermittent points along the 65 MPH zones.

An 18-month Study Plan was developed to assess impacts to travel speeds, safety records, enforcement, and the environment (air and noise). This required taking field measurements and accumulating data from agency record-keeping systems.

Due to the change in the fine schedule, efforts to develop, print and distribute fine schedules through the Administrative Office of the Courts for new police summons were expedited prior to initiation of the 65 MPH speed limit.

To make comparisons of the 55 and 65 MPH speed limits, a compilation of Abefore@ data was required for the Study Plan by the Task Force.

When the 65 MPH speed limit began on May 19th, all these requirements were completed and in place.

Travel speeds were measured at least once every three months at various points along New Jersey highways posted at 65 MPH and 55 MPH through the use of detector stations. The type of detector station used on the state highways is an in-ground inductive loop detector that measures the speed of each vehicle which passes over the detection zone. This data is collected and processed to analyze the travel speeds and volumes. Attached is a Monitoring Report of measurements made on the state highways. At various locations, Abefore@ measurements were taken prior to May 19, 1998 (when 65 MPH went into effect), with Aafter@ measurements taken and presented for comparison. The volume of vehicles for each 24-hour period is presented. Then, travel speeds are presented in terms of Aaverage@ Amedian@ and A85th-percentile."

Average speed is the most commonly used speed statistic and is the summation of all individual speed measurements divided by the total number of vehicles.

Median speed is the speed which is exceeded or equaled by exactly half the vehicles from which the data was collected.

85th-percentile speed is sometimes referred to as the critical speed as it is commonly used as a guide in establishing reasonable speed limits. This represents the speed which 85% of the vehicles are traveling under.
The last three columns of the tables in Appendix B reflect the percentage of motorists exceeding 65 MPH, 70 MPH and 75 MPH.

Environmental impacts were measured by the DOT for both air and noise levels. Air quality and noise level measurements were made by models, based on field measurements of travel speeds and volumes. Actual field measurements would not be useful as they would be subject to undetermined factors influencing readings.

Throughout the study period, the State Police collected data on accidents and violations.

III. Results

A. Travel Speeds
Changes in the measured average travel speeds in the 65 MPH zones were found to experience nominal differences compared to prior 65 MPH conditions, as some locations increased and some decreased, generally less than 2 mph. Appendix B identifies the travel speeds taken at various time intervals for different sections of the state highway system.

The only difference to this similarity appears on the New Jersey Turnpike, where the Abefore@ and Aafter@ travel speeds are within 3-4 mph. The "after" speeds on the Turnpike are comparable to the other highways in the study. There were different measuring techniques between the DOT and the three toll authorities, however, the measuring techniques used were consistent during the Abefore@ and Aafter@ time periods. Appendix C contains the speed surveys from the toll authorities.

In conclusion, the reasons for the nominal differences in the travel speeds could be due to many factors, including enforcement, public outreach, respect for the speed limit, uniformity in traffic flows, and increased fines. The change to the 65 MPH speed limit during the study period had minimal impact on actual travel speeds.

B. Environmental Impacts
Environmental impacts were studied by the DOT for both air and noise levels. Air quality and noise levels were determined by models based on field measurements of travel speeds and volumes. Increases in speed tend to mean increases in emissions, however, changes in routes by motorists could affect the emissions too.

In order to estimate the impact on air quality, the analysis was conducted to investigate potential travel speed changes and traffic diversions to the higher-speed facilities. Because the speed limit change affected facilities throughout New Jersey, the New Jersey Statewide Model was utilized. In order to estimate the change in emissions resulting from the higher-speed facilities, speeds for the modeled traffic volumes were calculated using the network Post Processor for Air Quality (PPAQ). Emission estimates were calculated within PPAQ using the MOBILES emission program developed by the US EPA.

The air quality study was conducted based upon a set of observed speed and volume data collected over the 18-month study period. The emissions were calculated for the "before@ condition using data collected prior to the speed limit increase and the "after@ condition using data collected after the increase. The results of these conditions were compared to determine air quality impacts.

Changes in travel speed can potentially affect many aspects related to travel, which in turn could affect the rate of emissions. The observed data indicate that the speed changes on most of the 65 MPH facilities increased an average of one mph, except for some of the Turnpike facilities which increased by an average of four mph. Therefore, the speed changes from the observed data are reflected in the air quality analysis.

Another aspect is the potential for traffic diversion to the higher speed facilities, as the increased speed would provide potential travel timesavings over the nearby parallel routes. However, the small amount of traffic diversion observed directly from the data was inconclusive. The changes reflected are within the margins of error associated with the data collection equipment and technique.

Considering that the observed aggregate speed changes listed above and that the levels of potential diversion for the increased speed are relatively minor, the emission analysis assumed that diversion would not be significant. The air emission analysis indicated nominal increases of 0.20%, 0.90%, and 1.15% for Volatile Organic Compounds (VOC), Nitrous Oxides (NOx), and Carbon Monoxides (CO) emissions, respectively.

It is generally accepted that it requires a change in noise level of 3 decibels or more to be perceived by the general public. The change in travel speeds reported in this study are at most 2 mph. This small change in travel speed would not generate an increase in noise levels of 3 decibels and therefore would not be a perceptible change in the noise environment adjacent to the highways.

C. Safety
Fatal accidents in 65 MPH zones have decreased since the implementation of the 65 MPH speed limit. There were ten fewer deaths, representing a 9.6 percent decrease, on the sections of highway that now have the 65 MPH speed limit and seven fewer fatal accidents, representing a 7.9 percent decrease, than on those sections of highway for a comparable time period. It should be noted, however, that fatal accidents comprise less than one percent of all reported accidents and may not be a statistically relevant indicator of safety.

Notably, accidents on sections of highways with 65 MPH speed limits increased 18.3 percent. Accidents with injuries increased by 9.4 percent, and the total number of people injured increased by 5.9 percent from a comparable time period. An analysis of certain 65 MPH zones and adjacent 55 MPH zones were made for comparison basis with accidents from the 12-month period before 65 MPH was implemented, to the 12-month period after 65 MPH was implemented. The highways analyzed were I-78, I-80 and I-287. The findings showed that accidents increased in the 65 MPH zones by 12.0%, and increased in the 55 MPH zones by 12.9%.

Accident rates fluctuate over time. In periods between 1984 and 1996, rates vary as much as 12 percent per year. The study captured data for a fixed 18-month period. Accordingly, it is not possible to determine whether the increase in accidents in 65 MPH zones represents a normal fluctuation in accident rates or suggests that increased speed contributes to increased accidents. Appendix D identifies overall fatal accidents and total accidents in 65 MPH roadway segments and individually for each roadway segment selected for the test period.

D. Enforcement
Appendix F provides information on State Police enforcement efforts since implementation of the 65 MPH speed limit. The table summarizes the number of speeding summons (broken down incrementally by the number of miles over the speed limit), accident data (broken down by accident type), and "aggressive driver" violations (broken down by specific statutory violations). The enhanced speed enforcement campaign of the State Police resulted in approximately one-third of all speeding summons being issued for speeding 1-9 miles over the posted speed limit.

The following summarizes the findings of the 18-month study period effort:

Average increase in travel speeds of 1 mph, on the various roadway sections in the 65 MPH zones, with the exception of the Turnpike which increased 3-4 mph, on various segments. The "after" speeds on the Turnpike ranged from 63 to 68 MPH, falling in line with the "after" speeds on the other state highways.

Environmental impacts regarding air quality and noise were only nominally affected due to the nominal change in the travel speeds.

Fatalities decreased 9.6% and fatal accidents decreased 7.9% in the 65 MPH zones over a similar 18-month period prior to the study period.

Reported accidents increased 18.3% in the 65 MPH zones over a similar 18-month period prior to the study period. Adjacent 55 MPH zones had slightly higher increases in the number of reported accidents than the 65 MPH zones during a similar time period.
Some roadway sections in the 65 MPH zones appear to be very favorable for the 65 MPH speed limit; however, with other roadways, the information is mixed. The data is not conclusive. Therefore, it is recommended that any conclusive long-term decisions on the 65 MPH speed limit cannot be made at this time. Rather, it is recommended to extend the study period another 18 months, in order to perform a more detailed analysis that is completed in a time frame more acceptable for professional practice in the area of transportation safety.

As noted previously, accident rates fluctuate over time. In periods between 1984 and 1996, rates vary as much as 12 percent per year. The study captured data for a fixed 18-month period. Accordingly, it is not possible to determine whether the increase in accidents in 65 MPH zones represents a normal fluctuation in accident rates or suggests that increased speed contributes to increased accidents.

The Department of Transportation, in consultation with the Attorney General, the New Jersey Turnpike Authority, the New Jersey Highway Authority, and the South Jersey Transportation Authority, recommends that the existing roadway segments currently posted at 65 MPH be maintained at 65 MPH, and that no additional mileage be added at this time.

Monitoring by all agencies on the Task Force should continue with reports on the maximum speed limit, submitted to the Commissioner of Transportation. Furthermore, staff should take a closer look at any locations experiencing higher frequencies of accidents. At this point, it is not known why accidents increased, and it raises great concern. However, the Task Force needs to learn more about the increases and implement appropriate safety counter-measures at appropriate locations, along with a proactive outreach to educate motorists on safe travel. An increase in the size and scope of the study is warranted. Further, analysis is needed on parallel and adjacent roadways to better understand the overall effects.

Continue on to Appendix

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  Last Updated:  June 5, 2007