KLK571 Safety Impacts of Using Wider Pavement Marking in Two-Lane Rural Highways in Idaho
ITD Research Project 242; Task Order Number UI-15-02
Principal Investigators
- Ahmed Abdel-Rahim
- Kevin Chang
- Brian Dyre
ITD Project Manager
- Brent Jennings
FHWA Project Advisor
- Lance Johnson
Student Researchers
- —
Research Problem Statement
The purpose of this research is to determine if the use of wider longitudinal pavement markings for center lines, lane lines and edge lines can provide critical information to drivers that will help them to better identify the roadway alignment and maintain appropriate lane position. In the State of Idaho, the largest contributors to single vehicle crashes have been the inability of the driver to maintain his or her lane position (22%) and the driver's travel speed (22%). Driver inattention and distraction (11%), driver overcorrection (5%), and driving to the left of center (2%) also represent contributing circumstances (2012 data). This study will determine if the added visual cues provided by wider longitudinal pavement markings can aid in the reduction of future vehicle crashes and driver fatalities.
Wider longitudinal pavement markings may provide a safer environment for drivers by increasing visibility. The safety impact of wider edge lane lines has been examined in at least three states (Kansas, Michigan, and Illinois) and these initial studies have concluded that there is "enough statistical evidence to support the positive safety effects of wider edge lines installed on rural, two-lane highways.” The crash types that are likely to be (positively) impacted by wider pavement marking include run-off-the-road and opposite direction crashes. These crash types have, historically, had a high crash severity index. This research project supports the Idaho Transportation Department's Strategic Highway Safety Plan wherein lane departure is one of the critical focus areas. This research project supports the Idaho Transportation Department's Strategic Highway Safety Plan wherein lane departure is one of the critical focus areas.
The Manual on Uniform Traffic Control Devices, or MUTCD, specifies a nominal width of four (4) inches for longitudinal pavement markings. For this study, wider pavement markings, including, but not limited to, six (6) inches and eight (8) inches will be implemented to determine if there is a correlation between these wider pavement markings and impactful driver behavior and enhanced user safety.
ITD staff will be able to apply the results from the analysis conducted as part of this project study to more accurately assess the expected safety performance of alternative pavement marking practices in Idaho and to accurately determine the cost / benefit ratio of using wider pavement markings in different parts of the state highway system.
In addition to the before-and-after safety studies, a driver-simulation based study will be conducted to assess the impact of wider pavement marking on speed and lane position under different geometric and driving conditions.
Project Objectives
The primary objective of this project is to evaluate the safety effects of wider pavement markings on rural two-lane highways in Idaho. Observational Before-and-After Studies
The focus of the safety evaluation is wider pavement markings using observational before-and-after studies. Wider pavement markings will be implemented at different sites throughout the state. The sites will be selected to represent the diverse geometric and operational characteristics in the Idaho state highway system. Two enhanced statistical analyses, namely empirical Bayes before-after analysis and a cross-sectional safety comparison, will be utilized to assess the safety impacts of implementing wider pavement marking in different sites throughout the state.
Driver Simulation-Based Studies
In addition to the field data analysis, a driver simulator study will be conducted to assess the potential impact of wider pavement markings on speed and lane position under different geometric and driving conditions for different driver groups.
Collectively, the results from both studies will provide ITD with a comprehensive understanding of the potential safety benefits of wider pavement marking.
Project Tasks
The proposed project is a three-year project. In the first year, the sites to be included in the study will be identified and selected. Wider pavement marking will be implemented on these sites during year-1 of the project. The driver simulation study will also be conducted as part of year-1 activities. In the subsequent two years of the project, field data will be collected at different test and control sites at different times of the year and the before-and-after study will be conducted using three years of before data and two years of after data. The results of the driver simulation study will be documented in a interim report by the end of year-1 of the project. The results of the before-after safety study will be published in a final report by the end of year-3 of the project.
Task 1. Background and literature review documenting previous studies that examined the safety benefits of wider pavement marking. This task will also include a survey and phone interviews to document the state-of-the-practice in wider pavement marking implementation at different state DOTs and other transportation agencies.
Task 2. Document the characteristics of roadway segments that can be included in the study. The documentation will include geometric data (number of lanes, lane width, shoulder width and type, median width and type, shoulder and centerline rumble strips installed, horizontal curves, grade, AADT, as well as crash history for the past five years (2010-2014).
Task 3. Work with ITD staff and the project TAC to identify up to a total of ten (10) test and control sites that will be used as part of this study. The test sites will be selected to represent the diverse geometric and operational characteristics in the state highway system. The control sites will have geometric and traffic flow characteristics similar to the test sites.
Task 4. Work with ITD staff to implement wider pavement marking in the test sites selected for this project.
Task 5. Develop the initial driver simulator test environment and conduct pilot testing. The test environment will include two-lane two-way segments as well as multi-lane segments. The segments will also have diverse geometric characteristics similar to what a driver would typically expect on Idaho’s state highway system.
Task 6. Finalize the driver simulator test environment and conduct testing for a sample of 60 drivers covering different driver characteristics such as age and gender. The tests will be conducted under daytime and nighttime, and dawn and dusk conditions.
Task 7. Conduct data analysis for the results of the driver simulator study.
Task 8. Document the results and findings of the driver simulator study in an interim report to the project TAC.
Task 9. Develop the statistical models that will be used in the before and after crash analysis and the test and control sites. Two enhanced statistical analyses, namely empirical Bayes before-after analysis and across-sectional safety comparison, will be utilized to assess the safety impacts of implementing wider pavement marking in different sites throughout the state.
Task 10. Collect before and after crash data and conduct before and after crash analysis. The before period for the study will cover 5-year period (2010-2014). The after period will cover at least one and half year period (June 2015-December 2015 and all 2016 data).
Task 11. Calculate the additional labor and material costs associated with the wider pavement markings for this study (cost/benefit ratio).
Task 12. Project final report.
Project Communication Schedule
Monthly project progress report (ITD 771)
Quarterly project meeting with the project's technical oversight committee report
Needs and Requirements
The specific needs and requirements for this project include the following aspects:
- Work with ITD staff to document the current state-of-the-practice with regard to wider pavement marking implementation;
- In conjunction with ITD staff, determine the characteristics of roadway segments that will be included in the study. Characteristics may include number of lanes, lane width, shoulder width and type, median width and type, shoulder and centerline rumble strips installed, horizontal curvature, grade, AADT, and roadway crash history for the past five years (2010-2014);
- Work with ITD staff and the project TAC to identify up to a total of ten (10) test and control sites that will be used as part of this study; and
- Work with ITD staff to implement wider pavement marking in the test sites selected for this project.
Required Outputs
The required outputs and deliverables for this project will include: monthly progress reports, written quarterly reports to be submitted prior to quarterly meetings, a literature review summary, an interim report on driver simulation results, a PowerPoint summarizing study findings and recommendations from the study, and draft articles suitable for publication in the ITD electronic newsletter at both the start and end of the project.
Implementation
The outcome of the project will provide ITD with the data needed to make better decisions on the implementation of wider pavement marking and identify locations where wider pavement marking would be most effective.
Expected Outcomes/Savings to ITD
This research project aligns with Idaho’s Strategic Highway Safety Plan and supports the top performance measure of eliminating fatalities and serious injuries on all Idaho roadways.
Benefits of this project include:
- Assessment of the potential safety impact of using wider pavement marking based on field implementation,
- Cost-benefit analysis of using wider pavement marking at different sites in two-lane-rural highways, and
- Guidelines for ITD staff on the use of wider pavement marking in two-lane rural highways.
Monthly Progress Reports (ITD 771) and Task Progress Charts
Draft report due: 9/30/17
Project status:
Active
Final report due date:
12/31/17