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State Safety Data Systems Questions & Answers

Posted 1/2/2013

Question: How have the FDEs changed from the original Guidance Memo of August 1, 2011?

Answer: The August 1, 2011 Guidance Memorandum on Fundamental Data Elements (FDEs) to Improve the Highway Safety Improvement Program, identified 38 data elements that provided a sufficient set of roadway and traffic data elements that a State could combine with crash data in an analysis process to identify safety problems and to make more effective safety countermeasure decisions for their HSIP. The specific changes in the FDEs between the August 1, 2011 Guidance Memorandum and the Guidance on State Safety Data Systems are identified in a Crosswalk Table. In addition to depicting these changes, the Crosswalk Table identifies the corresponding Highway Performance Monitoring System (HPMS) data items. In general these changes are:

  1. Change in nomenclature - The FDEs provided in the August 1, 2011 Guidance Memorandum used some naming conventions from the Safety Analyst program. While these FDEs equated with MIRE data elements, to adhere to the requirements of MAP-21, the names of the subset of MIRE elements are changed to the names provided in the MIRE Version 1.0 document.

  2. Elimination of derived elements - The FDEs in the August 1, 2011 Guidance Memorandum contained some derived elements (i.e., a single FDE that was the combination of two MIRE elements). The Guidance on State Safety Data Systems eliminates derived elements and uses the MIRE Version 1.0 elements from which they were derived.

  3. Deletion of non-MIRE elements - The FDEs in the August 1, 2011 Guidance Memorandum included some non-MIRE elements (i.e., date opened to traffic and leg segment ID) that are deleted to adhere to the requirements of MAP-21.

  4. Creation of a reduced set of FDEs for low traffic volume roadways - It is expected that low traffic volume roadways (ADT < 400) will have no more than two through lanes and partial or no access control, thus will require a reduced set of elements to identify and describe these low volume roads. Table 2 lists the reduced set of roadway elements for low volume roads.


Crosswalk Table

FDE in August 1, 2011 Memorandum1 FDE in Guidance on State Safety Data Systems: MIRE Name (Element Number)2 HPMS:
Data Item (Item Number)3
Roadway Segment
Segment ID Segment Identifier (12) Route Number (17); Begin Point (4); End Point (5)
Route Name* Route Number (8) Route Number (17)
Alternate Route Name* Route/street Name (9) Alternative Route Name (20); Route Signing (18)
Route Type* Federal Aid/ Route Type (21) NHS (64)
Area Type* Rural/Urban Designation (20) Urban Code (2)
  Surface Type (23)# Surface Type (49)
Date Open to Traffic^    
Start Location* Begin Point Segment Descriptor (10) Begin Point (4)
End Location* End Point Segment Descriptor (11) End Point (5)
Segment Length* Segment Length (13) Section Length (7)
Segment Direction Direction of Inventory (18)  
Roadway Class* (Roadway Functional Classification) Functional Class (19) Functional System (1)
Median Type Median Type (54)  
Access Control* Access Control (22) Access Control (5)
Two-Way vs. One-Way Operation* One/Two-Way Operations (91) Facility Type (3)
Number of Through Lanes* Number of Through Lanes (31) Through Lanes (7)
Interchange Influence Area on Mainline Freeway@ Location Identifier for Roadway at Beginning Ramp Terminal (197)  
Location Identifier for Roadway at Ending Ramp Terminal (201)
AADT* Average Annual Daily Traffic (79) AADT (21)
AADT Year* AADT Year (80) AADT (21) (coded for current year)
  Type of Governmental Ownership (4)# Ownership (6)
Intersection
Intersection Identifier Unique Junction Identifier (120)  
Location@ Location Identifier for Road 1 Crossing Point (122)  
Location Identifier for Road 2 Crossing Point (123)
Intersection Type Intersection/Junction Geometry (126)  
Date Open to Traffic^    
Traffic Control Type Intersection/Junction Traffic Control (131)  
Major Road AADT AADT (79) [for Each Intersecting Road]  
Major Road AADT Year AADT Year (80) [for Each Intersecting Road]  
Minor Road AADT AADT (79) [for Each Intersecting Road]  
Minor Road AADT Year AADT Year (80) [for Each Intersecting Road]  
Intersection Leg ID Unique Approach Identifier (139)  
Leg Type^    
Leg Segment ID^    
Ramp/Interchange
Ramp ID* Unique Interchange Identifier (178) Route Number (17); Begin Point (4); End Point (5); Facility Type (3)
Date Opened to Traffic^    
Start Location Location Identifier for Roadway at Beginning Ramp Terminal (197)  
Ramp Length Ramp Length (187)  
Ramp Type@ Roadway Type at Beginning Ramp Terminal (195)  
Roadway Type at Ending Ramp Terminal (199)
Ramp/Interchange Configuration Interchange Type (182)  
Ramp AADT* Ramp AADT (191) AADT (21)
Ramp AADT Year Year of Ramp AADT (192)  
  Functional Class (19)#  
  Type of Governmental Ownership (4)#  

1 Based on Guidance Memorandum on Fundamental Roadway and Traffic Data Elements to Improve the Highway Safety Improvement Program dated August 1, 2011.
2 Guidance on State Safety Data Systems, Tables 1 and 2, dated December 27, 2012.
3 Highway Performance Monitoring System Field Manual, March 2012.
*Highway Performance Monitoring System full extent elements are required on all Federal-aid highways and ramps located within the grade-separated interchanges, i.e., National Highway System (NHS) and all functional systems excluding rural minor collectors and locals.
@This FDE was a derived data element that is now split into the two MIRE data elements from which it was derived.
# This data element was added to the FDEs in the Guidance on State Safety Data Systems.
^ This data element was deleted for the FDEs in the Guidance on State State Safety Data Systems.

Page last modified on September 12, 2013.
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