Safety Analysis Tools
In addition to conducting research, HSIS resources are also used to develop products that can be used by practitioners in the analysis of safety problems.
FHWA Pedestrian and Bicycle GIS Safety Analysis Tools
Geographic Information System (GIS) software turns statistical data such as accidents and geographic data such as roads and crash locations into meaningful information for spatial analysis and mapping. In this suite of pedestrian and bicycle safety tools, GIS-based analytical techniques have been applied to a series of pedestrian and bicycle safety issues. The tools included in this suite can be used to develop the following:
- high pedestrian crash zones
- safe routes for walking to school
- safe bicycle routes
FHWA GIS Safety Analysis Tools
Computerized crash analysis systems in which crash data, roadway inventory data, and traffic operations data can be merged are used in many state and municipalities to identify problem locations and assess the effectiveness of implemented countermeasures. By integrating this traditional system with a geographical information system (GIS), which offers spatial referencing capabilities and graphical displays, a more effective crash analysis program can be realized. The analysis tools include five separate programs to evaluate crashes:
- Spot/Intersection Analysis
- Strip Analysis
- Cluster Analysis
- Sliding-Scale Analysis
- Corridor Analysis
Pedestrian and Bicycle Crash Analysis Tool (PBCAT)
The Pedestrian and Bicycle Crash Analysis Tool (PBCAT) is a crash typing software product intended to assist state and local pedestrian/bicycle coordinators, planners and engineers with improving walking and bicycling safety through the development and analysis of a database containing details associated with crashes between motor vehicles and pedestrians or bicyclists. One of these details is crash type, which describes the pre-crash actions of the involved parties. After developing a database of crash information, PBCAT users can analyze the data, produce reports, and select countermeasures to address the problems identified by the software.
Safety Effects of Horizontal Curve and Grade Combinations on Rural Two-Lane Highways
The safety effects of horizontal curves and grades on rural two-lane highways have been quantified in the American Association of State Highway and Transportation Officials (AASHTO) Highway Safety Manual (HSM), but it was not previously known whether and how the safety performance of horizontal curves and grades interact. Furthermore, there are no established safety effects for crest and sag vertical curves, and it is unknown whether and how the safety performance of crest or sag vertical curves is affected by the presence of horizontal curves.
The objective of this study was to quantify the combined safety effects of horizontal curves and grade combinations and express the results as crash modification factors (CMFs) that can be considered for use in the AASHTO HSM.
Download the Excel calculator tool here.
Across the Nation, many agencies have been replacing conventional incandescent light bulbs in traffic signals with light-emitting diodes (LED). LEDs are primarily installed to reduce energy consumption and decrease maintenance. In addition, LEDs are expected to last much longer compared with incandescent bulbs and tend to age gradually. However, a recent study revealed several potential problems with LEDs, including their inability to melt snow and issues related to visual discomfort caused by glare at night.
During late-night flash (LNF) mode (from late night to early morning hours), traffic signals flash yellow for one road (typically, the major road), requiring caution but no stopping, and flash red for the other road (typically, the minor road), requiring drivers to stop and then proceed through the intersection after yielding to the traffic on the major road. The intent of LNF is to reduce energy consumption and delay during periods of low traffic demand. However, in recent years, many agencies have begun replacing LNF with normal phasing operation because of safety concerns.