Safety Data Case Studies

Roadway Safety Data and Analysis Case Study:
Safety Analysis in Project Development in Louisiana

Downloadable Version
PDF, [1.97 MB]

Introduction

State Departments of Transportation (DOTs) have many opportunities to improve safety-some of the most important opportunities arise in programs outside the traditional state safety engineering program. Addressing safety in multiple types of projects and programs creates a coordinated, Department-wide and statewide safety focus, saves lives, reduces injuries, and saves money.

The purpose of this case study is to describe the success experienced by the Louisiana Department of Transportation and Development (LADOTD) using safety data and safety analysis techniques in a broad range of project development practices in maintenance, design exceptions, environmental reviews, work zone construction and operations, and local roadway owner coordination.

Audience

This case study applies to the following audiences:

• State Department of Transportation: Maintenance, Environmental Planning, Design, Construction, Safety Engineering, and Asset Management Units.
• Local and Regional: City and County Public Works/Engineering/Transportation Departments. Metropolitan Planning Organizations. Regional Planning Commissions personnel.
• Local and Tribal Technical Assistance Program personnel.

Background

The scope of this case study includes all public roads in Louisiana, and multiple operations within the LADOTD. Safety practices are implemented in the following areas:

• Maintenance: The project designers implement low cost safety countermeasures into the project such as pavement wedge, rumble strips, advance warning signs, and others from a list of baseline safety improvements provided by LADOTD. If a Road Safety Assessment/Audit (RSA) was performed for the project, then further countermeasures can be implemented as detailed in the RSA final report. Annually, the LADOTD processes approximately six-to-eight RSAs for preservation projects over the course of the year.(1)

• Design: The crash data for the project site is reviewed to check for an abnormal section or of a prevailing collision type. In some cases, a predictive analysis is performed to compare the built condition to the existing condition. Engineers consider low cost safety improvements, and use the Crash Modification Factor (CMF) Clearinghouse to help select countermeasures. Overall, less than 10 percent of projects have design exceptions, which include projects in both rural and urban settings.(2)

• Environmental: Engineers gather data from the Highway Performance Monitoring System (HMPS). Gathering the full data element list required for the Interactive Highway Safety Design Model (IHSDM) is labor intensive and consumed a majority of the time spent on the safety analysis. Engineers convert crashes to various dollar amounts based on severity of the crash by using a National Highway Traffic Safety Administration (NHTSA) report titled "The Economic Impact of Motor Vehicle Crashes";(3) and including the consumer price index.(4) Finally, the designers consider the results of the cost-benefit analysis to select the preferred alternative.

• Work Zone Construction and Operations: Engineers perform a safety analysis for the Transportation Management Plan (TMP) and select the appropriate countermeasures to address identified issues as part of the construction phase. Analysts also use the CMF Clearinghouse to help identify countermeasures based on the observed crash types.

• Local roadways: The LADOTD funds a local road safety program. Engineers on staff at LADOTD work with the local agencies to perform the same type of advanced safety analysis that is performed for the State roads. Currently, the program is working on a systemic curve program.(5)

Specific Guidelines and Practices

LADOTD established specific guidelines for projects in each of the targeted areas. Each has a set of analyses, procedures, and rules that project managers use to decide when and how to apply safety improvement measures. The procedures and guidelines for each area are:

• Maintenance: The pavement preservation projects across the State are put on a list for the upcoming year. Each of the districts fills out a checklist and informs the LADOTD of any abnormal or overrepresented crash types, in which case an RSA must be performed. If the project does not require an RSA, the districts need to fill out the LADOTD's baseline safety improvements checklist and indicate if a low cost countermeasure was considered. The low cost countermeasures include items such as rumble strips, oversized signs, pavement wedge, and removing foliage to improve site distances.(1)

Resource Materials for Maintenance:

• Design: LADOTD aims to meet design standards on all reconstruction/design projects. The design exception form includes name, project number, design standards being followed, criteria that do not meet standards, and design waivers (things that don't meet American Association of State Highway and Transportation Officials (AASHTO) policy). Thirteen of the controlling criteria found on the design exception form are Federal Highway Administration (FHWA) Controlling Design Criteria. The controlling criteria include items such as design speed, lane width, super elevation, shoulder width, horizontal/vertical alignment, etc.(6) Part of the design exception process is for the engineer of record to include a safety analysis which states that safety will not be impacted or that the impact will be minimal.(2)

Resource Materials for Design:

• Environmental: The National Environmental Policy Act (NEPA) process provides an opportunity to include safety analysis in new roadway construction projects.(7) In 2012, for a realignment project (Interstate 12 to Bush, LA), LADOTD utilized the IHSDM software which supports the Highway Safety Manual (HSM) to quantify the safety impacts of the different realignment alternatives.(4)

Resource Materials for Environmental:

• Work Zone Construction and Operations: The LADOTD formed a multi-disciplinary team (construction, traffic, safety, etc.) to address the Final Rule for Work Zone Safety and Mobility within their Engineering Directives and Standards Manual (EDSM). The EDSM outlines the requirements for the Transportation Management Plan for a particular project. The EDSM classifies projects into four different levels:(8)

One component of the TMP is a safety analysis.  The EDSM requires that a safety analysis be performed for Level 3 and Level 4 projects, and it also defines what a safety analysis consists of for temporary traffic control.  The safety analysis performed for the TMP uses crash data, but does not take the next step and use an analysis from the HSM as the goal of the TMP is not a long term fix.  One way that high crash locations are defined is by saying they are 'abnormal locations'.  The analyst looks at the crash data in two ways - crash rate and crash types (if there is an over representation of a certain crash type).(9)

Resource Materials for Work Zone Construction and Operations:

• Local roadways: LADOTD is working to build and maintain a comprehensive inventory of local roadway systems in order to perform up-to-date safety analysis of local roadways.  In October of 2013, LADOTD contracted a private consultant to collect local road asset data.  LADOTD invited local agencies to be involved with the contract.  The current contract is for three years and involves the consultant gathering roadway asset data through the use of video and other active instruments.  The consultant conducts post-processing of the videos after field collection, tags the data in GPS and delivers a spatial database to LADOTD.(5)

Benefits

The benefits of implementing safety into the LADOTD practices are highlighted below in the following examples.

• An example of safety implemented in TMPs (Work Zone Construction and Operations): An engineer conducted a safety analysis for a Level 4 project on Interstate 12/Airport Road-US 11 and found an 'abnormal' circumstance due to the crash rate being two times the average.  The LADOTD investigated the situation further and discovered that speed was a contributing factor to the increased collisions.  The solution was to increase law enforcement in the area to encourage motorists to adhere to the Work Zone speed limits.
• Safety in Design Exceptions: For a project that has a severe curve (as, for example, on a section of Interstate 10 from Veteran's to Clearview), instead of straightening the curve, low cost countermeasures may be installed such as rumble strips and additional signing.

Summary

Funding, LADOTD processes, and lessons learned are outlined below for each of the safety practices discussed in this case study.

Funding:

• Maintenance: The RSA can recommend countermeasures without considering a specific budget.  However, the countermeasures that are implemented based on the RSA recommendations may be funded through the safety budget in addition to preservation funds.  Federal funds are available through the safety budget.  Additionally, major construction projects, such as straightening a curve, would not be considered a preservation project.(1)
• Design, Environmental, and Work Zone Construction and Operations: All of these practices were performed internally at LADOTD and therefore no additional costs were accumulated other than the cost of the person-hours to perform the work.
• Local roadways: LADOTD paid the private consultant $20 Million dollars over the course of six years for the asset data collection and processing.(5)

LADOTD Programs and Processes using Safety Analysis:

• Maintenance: Planning for an RSA is a collaborative effort between the LADOTD and the district where the project resides. If an RSA is not necessary then the districts will provide the LADOTD with a list of low cost safety countermeasures that were considered for the project.(1)
• Design:  Some of the districts have a design exception process in place; however, when the districts need guidance, they ask the LADOTD central office for assistance.  LADOTD prefers that the districts do their own analysis instead of the central office.  Each engineer of record develops their project's design exception requests and the chief engineer signs off on all of the design exceptions.(2)
• Environmental:  LADOTD performed the safety analysis for the NEPA process for new alignment projects on behalf of the Army Corps of Engineers, who owned the project.(10)
• Work Zone Construction and Operations:  The LADOTD trains its nine State districts on how to perform their own safety analysis.  A person from LADOTD met with the districts for one-on-one training, particularly those districts that had the most Level 4 projects.  The LADOTD developed guidelines to aid the districts in performing analysis.  LADOTD has also developed a software program to implement State-specific Safety Performance Functions (SPFs).  The software uses a cumulative probability function that determines if a crash type is over-represented and if it is statistically significant. 
• Local roadways: LADOTD is currently investing staff time to maintain the asset data in order for up-to-date safety analysis to be performed.  They added a position for an asset management engineer and hired a person with asset management and IT experience.  Currently, they are relying on consultants and local agencies to keep the data updated.(5)

Lessons learned:

• Maintenance:  Low cost safety improvements are possible through the coordinated efforts of a multi-disciplinary RSA team working together.(1)
• Design:  Thorough documentation of safety measures in the design exception process is a key part.  If there is a problem in the future, the engineer of record may not be available and the documentation will be used.  The district offices may see the design exception process as a burden, and the State headquarters will need to communicate the positive benefits to the districts.(2)
• Environmental:  LADOTD was only able to include roadways for which they had an SPF.  A key to a successful analysis is gathering accurate data to be used for the model.  LADOTD had some data that was used in combination with HPMS data and traffic forecasting models were used for future traffic volumes.  Additionally, calibration factors do not need to be used for this type of analysis since the analysis sought to compare the relative safety of the alternatives.
• Work Zone Construction and Operations: LADOTD advises other state agencies to first gain approval from the local FHWA Division Office and ensure that there is an assessment component to the process.  Also, the state agency may benefit from designating an "expert" within the agency.
• Local roadways:  LADOTD suggests other state agencies should first contact their local agencies and use data that already exists as a starting point.  Then a data collection effort can be planned to gather the remaining information.(5) One challenge for the local roadway asset data is maintaining up-to-date information on the roadways.  LADOTD is considering putting together an online map and allowing local agencies to log-in and provide updates for their local roadways.(5)

References

The following resources were consulted in development of this case study:

1. Road Safety Assessment (RSA) Process for Systems Preservation - April Renard, Dan Magri, Jim Chapman, Simone Ardoin, Mark Chenevert. Telephone Interview. April 8, 2014.
2. Safety Analysis in Design Exceptions - April Renard, Dan Magri, Chad Winchester, Joachim Umeozulu. Telephone Interview. April 9, 2014.
3. Blincoe, L, et al., et al. The Economic Impact of Motor Vehicle Crashes, 2010. Washington, DC : U.S. Department of Transportation National Highway Traffic Safety Administration, 2014. DOT HS 812 013.
4. Applying the Highway Safety Manual in NEPA using IHSDM. Renard, April. Washington, DC: Transportation Research Board, 2012.
5. Safety Analysis and Data Collection for Local Roads - April Renard, Jason Chapman. Telephone Interview. April 3, 2014.
6. Louisiana Department of Transportation and Development. Design Exception Waiver Form.
7. Cambridge Systematics, Inc. Integrating Road Safety into the NEPA Analysis: A Primer for Safety and Environmental Professionals. Washington, DC : Department of Transportation Federal Highway Administration, 2011. FHWA-SA-11-36.
8. Louisiana Department of Transportation and Development. Engineering Directives and Standards: Transportation Management Plans (TMP).  2012.
9. Safety Analysis in Transportation Management Plans (TMPs) - April Renard. Telephone Interview. April 2, 2014.
10. Highway Safety Manual (HSM) in NEPA Process (I-12 to Bush EIS) - April Renard, Dan Magri, Noel Ardoin, Jose Rodriguez. Telephone Interview. April 14, 2014.
11. U.S. Department of Transportation Federal Highway Administration. Road Safety Audits (RSA). FHWA Safety. [Online] [Cited: May 7, 2014.] http://safety.fhwa.dot.gov/rsa/.
12. American Association of State Highway and Transportation Officials (AASHTO). Highway Safety Manual. 1st Edition. Washington, D.C., 2010.

Explanation of Terms

Engineering Directives and Standards (EDSM) is a reference guide produced by the Louisiana Department of Transportation and Development (LADOTD).  The chapter on Transportation Management Plans (TMP) outlines the LADOTD's policy for TMP requirements.(8)

Road Safety Assessment/Audit (RSA) is a formal safety performance examination of an existing or future road or intersection by an independent, multidisciplinary team that qualitatively estimates and reports on potential road safety issues and identifies opportunities for improvements in safety for all road users.(11)

Safety Performance Functions (SPF) is an equation used to predict the average number of crashes per year at a location as a function of exposure and, in some cases, roadway or intersection characteristics (e.g., number of lanes, traffic control, or median type).(12)

Agency Contact Information

April Renard, P.E.
Engineer 5-LADOTD
april.renard@la.gov
(225) 379-1919

Louisiana Department of Transportation and Development (LADOTD)
Highway Safety Section 1201 Capitol Access Road
Baton Rouge, LA 70802