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NCHRP Project 17-35: Evaluation of Safety Strategies at Signalized Intersections

 

 

Evaluations of Low Cost Safety Improvements Pooled Fund Study

 

Treatment Databases

"One of the products of the Low Cost Safety Improvements Pooled Fund Study is a database developed for all to use to capture data regarding the installation of safety countermeasures. Often safety countermeasures are installed without any (easily obtained) record of dates, locations, or initial conditions. This information is crucial to perform evaluations, which has proved to be the most challenging part of our project thus far (capturing of data). The purpose of the databases is to allow people to easily and concisely capture the appropriate installation data, thereby making the data accessible for potential future evaluations.

Three formats of databases have been produced (and the databases are named appropriately) to accommodate different location referencing systems: GIS based systems, Link–Node based systems, and Logmile/milepost based systems. Use whichever database matches the type of measurement system that your agency uses. The databases are created in both Microsoft Excel and Access formats. The Access format allows more pull down menus and options, but the Excel database is set up in a very similar format to the Access database. There is a "readme.doc" file that can help walk users through entering data into the databases. The databases can also be customized to include additional strategies that are used in your state or locality and can be expanded to include additional information.

Please take time to look at these databases, as hopefully they will help you to capture the appropriate installation and conditional data needed for evaluations. Again, without capturing these data (time and location of the safety strategy's installation and some of the basic conditions prior to installation), it will be very difficult to do evaluations to determine the effectiveness of the safety countermeasures used. This project will evaluate as many safety countermeasures as possible, but is limited by the available installation data for the safety strategies; we all need to be responsible in making sure the appropriate data are captured and preserved.

Thanks much for your time and efforts. If you have any questions, feel free to contact the project manager, Kerry Perrillo Childress, at Kerry.Childress@dot.gov or 202–493–3318."

Overview

The following files are available for download in both Microsoft Excel and Microsoft Access:

A separate file is available for each type of referencing system (i.e., GIS, link/node, or logmile/logpost file). The files can be modified as needed to reflect the individual system of a jurisdiction.

Save the file to the hard drive of your computer by right–clicking over the link of the file you would like to download then click “Save Target As…”.

Microsoft Access

Regardless of referencing system, each Access file contains four tables and three entry forms as follows:

  • "Intersection Treatments" table and accompanying entry form,
  • "Segment Treatments" table and accompanying entry form,
  • "Spot Treatments" table and accompanying entry form, and
  • "List of Treatments from Pooled Fund Study" table.

Data can be entered either directly through the table or in the entry form. Entering data through the entry form is the preferred method of use. Treatment information is entered separately for treatments installed at intersections, along roadway segments or sections, and at spots such as curves. Spots are locations that are under 0.25 miles in length. The database will prompt the user to enter the treatment into the "Segment" table for sections longer than this. The database will automatically assign a unique ID to each project entered. This unique ID is the primary key in each of the tables but is only unique to the individual table.

Each table and corresponding form are equipped with one record of example data. This row can be deleted by the user in Table view.

The table "List of Treatments from Pooled Fund Study" provides information about treatments listed in the first six volumes of the NCHRP 500 Series Reports. The table provides a description of the treatment, the designation assigned by the Pooled Fund study (ex., LD7); a general assessment of the cost (high, medium, low); an assessment if the treatment is considered tried, proven, or experimental; a general assessment of the timeframe for implementation (short, medium, long); and the NCHRP 500 Series volume where the treatment is described. Copies of these six reports are included on the CD in Acrobat PDF format. The user can add to this list of treatments in this table from Table view. It can be customized to include treatments specific to the agency. When treatments are added to this table, they are automatically added to the drop down menu in all three forms.

In form view, some variables are equipped with drop down menus to expedite data entry and to ensure consistency in the entered values. However, the user is not limited to these values. Each variable is described in Table 1. In the description of each variable, any drop down menu values are indicated in parentheses.  

Microsoft Excel

The Microsoft Excel tables are intended to be used if Microsoft Access is not available. Data are entered directly into the tables. As with the Microsoft Access version, example data are presented in each of the files.

The variable names and descriptions are the same as their Microsoft Access versions and are explained in Table 1.

Table 1: Description of Variables
Variable Tables Referencing System Description
Area All All Surrounding area type (rural, urban, or suburban)
Comments All All Provide any additional comments
Condition Prior All All Describe condition of location prior to treatment installation
Construction All All Date construction started
Description All All Description of treatment employed
End X Coordinate Segment or Spot GIS Based GIS X coordinate at endpoint of treatment at a spot or segment
End Y Coordinate Segment or Spot GIS Based GIS Y coordinate at endpoint of treatment at a spot or segment
Intersection Type Intersection All Intersection type (Signalized, 3–leg; Signalized, 4–leg; Signalized, 5 or more leg; Two–way stop, 4 leg; Minor stop, 3–leg intersection; Four–way stop; Uncontrolled, 3–leg; or Uncontrolled, 4–leg)
Jurisdiction All All Name of County, City, or Region
Location Type Spot All Description of spot (Curve; Bridge; Tunnel; Midblock pedestrian crossing; Ramp; or Other)
Logmile end Segment or Spot Logmile Based Logmile at endpoint of treatment at a spot or segment
Logmile start Segment or Spot Logmile Based Logmile at starting point of treatment at a spot or segment
Logmile Street 1 Intersection Logmile Based Logmile of major street at intersection
Logmile Street 2 Intersection Logmile Based Logmile of minor street at intersection
Nearest end node Segment or Spot Link/Node Based Nearest node at end of spot or segment that is treated
Nearest start node Segment or Spot Link/Node Based Nearest node at start of spot or segment that is treated
Node Number Intersection Link/Node Based Node number of treated intersection
Offset from end node Segment or Spot Link/Node Based Offset from node that is referenced in "nearest end node"
Offset from start node Segment or Spot Link/Node Based Offset from node that is referenced in "nearest start node"
Open All All Date location opened to traffic after treatment was applied
Other changes All All Describe any other changes made at time of treatment application
Record ID All All Unique ID
Roadway Type Segment or Spot All Roadway type (Two–lane;Four–lane undivided; Four–lane divided; Four lane with center two–way left turn lane; Two–lane with center two–way left turn lane)
Roadway/Street Name Segment or Spot All Name of Roadway or Street
Route Number Segment or Spot All Route number (ex., SR 46)
Route Number Street 1 Intersection Link/Node or Logmile Based Route number of Street 1
Route Number Street 2 Intersection Link/Node or Logmile Based Route number of Street 2
Route Number Street 3 Intersection Link/Node or Logmile Based Route number of Street 3
Segment Length Segment All Length of treated segment
Spot length Spot All Length of treated spot (must be under 0.25 miles)
Start X Coordinate Segment or Spot GIS Based GIS X coordinate at start of treatment at a spot or segment
Start Y Coordinate Segment or Spot GIS Based GIS Y coordinate at start of treatment at a spot or segment
Street 1 Intersection All Major street name
Street 2 Intersection All Minor street name
Street 3 Intersection All Other minor street name
Treatment All All Description of treatment employed, link to list from pooled fund study
Volume Before All All Volume at location prior to treatment (in AADT)
X Coordinate Intersection GIS Based GIS X coordinate at intersection
Y Coordinate Intersection GIS Based GIS Y coordinate at intersection
Year of Volume All All Year or date volume was collected

For more information or help with these databases, please contact:

Kerry Perrillo Childress, PE
Federal Highway Administration
Turner Fairbank Highway Research Center
6300 Georgetown Pike
McLean, VA 22101
(202) 493–3318
(202) 493–3417—fax
kerry.childress@dot.gov