This research emphasizes two fundamental objectives: keeping vehicles on the roadway and minimizing the consequences of a vehicle leaving the roadway. Federal Highway Administration’s (FHWA’s) Roadway Safety research develops and promotes strategic initiatives that decrease roadway departures, reduce the number and severity of crashes resulting from roadway departures, and enhance knowledge and the tools and methods that will support sustainable efforts to monitor roadway departure crashes, understand their causes, and provide guidance for effective deployment of mitigation measures. The research emphasizes the provision of technical assistance and information to Federal, State, and local transportation agencies, in coordination with other stakeholder agencies.

Lane Departure Safety

The ideal result of any good highway design and traffic control system is to prevent a vehicle from leaving its traveled lane except when the driver intends that maneuver. Lane departure research considers ways to provide better information to the driver about the vehicle’s position on the road surface, and to indicate to the driver when the vehicle is straying towards a potentially dangerous situation. For example, enhanced visibility of lane markings and road signage support good decisionmaking by the driver. Measures such as rumble strips and rumble stripes give the driver a clear warning that the vehicle is crossing a boundary between safe and potentially unsafe conditions.

Roadside Safety

Roadside safety research is focused on reducing the number and severity of crashes when a vehicle leaves the road. The majority of roadside safety research at Turner-Fairbank Highway Research Center (TFHRC) is conducted as part of the FHWA’s Roadway Safety Program and its Strategic Plan. These efforts are supported by a multiyear, FHWA task order contract with the Center for Collision Safety and Analysis (CCSA) at the George Mason University (GMU) College of Science, and with the National Center for Manufacturing Sciences (NCMS). State-of-the-art computer models and crash simulations are used to study a number of topics, including the effectiveness of roadside hardware, such as guardrails, sign supports, and concrete barriers; vehicle-to-vehicle impact compatibility; and the causes of rollover crashes. Simulations are validated through component-level, pendulum, and full-scale crash tests at the Federal Outdoor Impact Laboratory at TFHRC. These studies result in the design and deployment of new roadside safety features and the establishment of guidelines for the appropriate use of those safety features. Researchers have developed guidelines for placement of cable median barriers; analyzed terrain effects on vehicle trajectories as they leave the road and approach roadside hardware such as longitudinal barriers; evaluated the safety performance of commonly used roadside hardware under the proposed new crashworthiness criteria; and studied the effectiveness of portable concrete barriers.

The results of this program are freely shared and have been the basis for other safety research worldwide. The finite element vehicle and hardware models created under this program are in the public domain for the purpose of encouraging safety research in both the public and private sectors, and academia.

For more information about this topic, visit the

• Federal Outdoor Impact Laboratory
• FHWA's Roadway Departure Safety Program

Intersection Safety

Intersections are junctions linking two or more roads, they are essential facilities enabling efficient and flexible movement of people or good from Point A to Point B, they are also planned areas where traffic conflicts occur and get resolved. Each year about one-quarter of traffic fatalities and one-half of traffic injuries occur at intersections. Intersection Safety is a focus area for FHWA. The FHWA’s Intersection Safety research program conducts research in innovative intersection designs that deliver optimum performance under various types of recurring traffic demand patterns; safe system intersection designs that reduce impact energy and crash severity; and data analysis research for identifying high crash locations and developing countermeasures.
 

Safety and Operational Impacts of Roadway Geometric Design

Roadway geometric design encompasses the layout and configuration of roadways, including elements such as horizontal and vertical alignments, cross-section, intersections and interchanges that applied to improvements/alternatives of existing and new roadway designs to ensure safe and efficient movement of vehicles, pedestrians and bicyclists. It generally involves a combination of engineering practices, design guidelines and standards, and research findings aimed to minimize crashes, improve traffic flow, and maximize the overall performance of the transportation system. Geometric design research at the Turner-Fairbank Highway Research Center (TFHRC) includes a wide range of research and activities to better understand and quantify the safety impacts of geometric designs, including:

1. Supporting implementation of FHWA’s Data-Driven Safety Analysis (DDSA) and integration of DDSA with the Safe System Approach.
2. Providing technology facilitation for the Interactive Highway Safety Design Model (IHSDM) and Highway Safety Manual (HSM).
3. Identifying existing knowledge gaps and research needs.
4. Investigating potential safety impacts of Connected and Automated Vehicle (CAV) technology on future geometric design.
5. Documenting existing applications of geometric design-related research and challenges in implementing new advanced techniques/methods. 

These activities are currently being led by the Geometric Design Laboratory (GDL) at TFHRC.  

The IHSDM, a suite of software analysis tools, was developed to evaluate the safety and operational effects of geometric design decisions on highways. Its Crash Prediction Module includes a faithful implementation of HSM Part C predictive methods and more. Other IHSDM tools include Design Consistency, Policy Review, Traffic Analysis, and Driver/Vehicle Modules as well as Economic Analyses and Crash Prediction Calibration tools. The software was first released to the public in 2003, with FHWA-led annual software enhancements through 2021. The final release, IHSDM 2021 (version 17.0.0), is available for free download via the IHSDM website. 

For more information about this topic, visit the following resources:

• Geometric Design Laboratory (GDL)
• Interactive Highway Safety Design Model (IHSDM)
• Highway Safety Manual (HSM)
• Data-Driven Safety Analysis (DDSA)