PC-ALAS User's Guide for Version 2.4 (September 1996)

Prepared by
Iowa Department of Transportation
Engineering Division
Office of Transportation Safety
(515) 239-1668

Table of Contents

List of Figures
List of Tables
Accident Database
Program Setup

Types of PC-ALAS Locations

Types of PC-ALAS Requests

Using the PC-ALAS Program

Extra help and information


List of Figures

List of Tables


The Office of Transportation Safety at the Iowa Department of Transportation has been developing an easy-to-use, yet powerful traffic accident records system for the past several years. The program, known as PC-ALAS, was developed with both the needs of the state as well as the needs of local enforcement and engineering in minde.

PC-ALAS is available to district and local offices of the DOT as well as smaller government agencies. This reduces both the demand on the Office of Transportation Safety to fill data requests and the time required for a local entity to have access to tha t same information.

PC-ALAS provides a flexible accident query and reporting system. Accident histories can be queried by a variety of location types:

Once the accidents for a location have been selected, it is possible to further reduce the data set by selecting ranges of values found within the accident records.

The number of search criteria is essentially unlimited.

While this is an unlikely combination of criteria (only a couple of accidents, if any, would qualify), it makes the point for the flexibility of the search criteria.

The beat is another powerful PC-ALAS tool. Using this feature, it is possible to define an entire area for repeated analysis.

This feature is excellent for "selective enforcement" as well as "problem identification".

Upon completion of the accident selection phase, several reporting options are available for either enforcement or engineering applications.

Accident Database

The Iowa accident database is compiled from accidents reported by:

All accidents occurring on public road systems in the State of Iowa that result in a fatality, a personal injury, or at least $500 property damage are included in the PC-ALAS database. Any personal information (name of driver, names of injured persons, e tc.) related to the involved parties has been removed.

Program Setup

1. Hardware configuration

2. Initial installation

3. Program and data updates

Types of PC-ALAS Locations

One of the frequently used abilities of PC-ALAS is its ability to retrieve the accident data for a specific location. In the system, there are several ways of defining a location. Careful considerations should be made when preparing to request data from the system. Following is a discussion of the different ways in which the location information is stored within Iowa's accident database.

1. Link-Node Locations

2. Milepoint/Milepost Locations

Types of PC-ALAS Location Requests

Using both milepoints/mileposts and the Link-Node system to store an accident's location, PC-ALAS has access to data through the following eight primary methods:

Descriptions of each of the several ways that PC-ALAS can retrieve accident data for a specific location or jurisdiction are discussed below. Prior to running a request with the system, it is important that the user understand the fundamental differences between each type of request.

1. Node Requests

2. Intersection or Interchange Requests

3. Link Requests

4. Node String Requests (Multiple Adjacent nodes)

5 and 6. Primary Route Milepoint/Milepost Requests

7. Beat Requests (a user defined geographic area)

8. Jurisdiction Requests (by city, county, or state)

Using the PC-ALAS Program

Notes for PC-ALAS version 1.0 users

1. Starting the program

2. The desktop

3. Help utility

4. Running a locational search

5. County summaries

6. Selecting accidents by accident characteristics

7. Engineering and law enforcement reports

8. Ranking reports

9. Specialty reports

10. Special features


1. Third party users

2. Reporting a program error

3. Making suggestions for program improvement


YOU ARE HERE!!! (Formatting decisions to be made!)

Extra help and information


A. Troubleshooting
B. Error Messages
C. Obtaining Node Maps and Traffic Flow Maps
D. Selection Criteria for Accident Isolation in PC-ALAS
E. Selection Criteria for Accident Isolation in PC-ALAS



last modified on January 9, 1997 by Michael D. Pawlovich (ISU/CTRE)

CTRE is an Iowa State University center.

Address: 2711 S. Loop Drive, Suite 4700, Ames, IA 50010-8664

Phone: 515-294-8103
FAX: 515-294-0467

CTRE Communications: Marcia Brink
CTRE Webmaster: Michele Regenold

Website: www.ctre.iastate.edu/

Iowa State University--Becoming the Best