In developing software for automated posting of messages on dynamic message signs, focus on the types of messages that are used often and changed frequently, and also include manual methods for posting.
Experience from iFlorida Model Deployment
A number of lessons learned were identified by observing sign operations during the evaluation with regard to using dynamic message signs (DMS) for traveler information dissemination:
- Validate travel time estimates before being used for traveler information. The CRS software miscalculated travel times that were used for DMS messages, resulting in inaccurate travel times being displayed to the public. One iFlorida stakeholder suggested that the process used to produce travel times for DMS messages should be thoroughly validated before being used in the field.
- In developing software for automating messages posted on DMS, focus on the types of messages that are used often and change frequently. The CRS software included tools to generate travel time DMS messages automatically. FDOT operational policies for these signs meant that congestion messages were used most often during high traffic periods-exactly the time when sign messages changed frequently (because of changes in travel times). This required RTMC operators to manage congestion sign messages manually during rush hour periods while travel time messages, used when congestion was not present, were generated automatically. The workload on RTMC operators might have been reduced if congestion messages were automated rather than travel time messages.
- Include software tools for managing DMS travel time messages manually in the event that the automated travel times become unavailable or unreliable. FDOT experienced significant reliability problems with their travel time network, so that travel time estimates were often unavailable. Although the CRS software was intended to include tools to estimate travel times based on historical values, these tools were not used. When the CRS failed, FDOT discovered that (a) static historical travel times worked well for most of the day and (b) RTMC operators could update signs manually to reflect current travel conditions when congestion occurred, although they made these updates by circumventing the CRS software.
Author: Robert Haas (SAC); Mark Carter (SAIC); Eric Perry (SAIC); Jeff Trombly (SAIC); Elisabeth Bedsole (SAIC): Rich Margiotta (Cambridge Systematics)
Published By: United States Department of Transportation Federal Highway Administration 1200 New Jersey Avenue, SE Washington, DC 20590
Source Date: 01/30/2009
EDL Number: 14480URL: http://ntl.bts.gov/lib/31000/31000/31051/14480.htm
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Lesson of the Month for March, 2010 !
Major Initiatives > Integrated Corridor Management Systems
Major Initiatives > Nationwide Surface Transportation Weather Observing and Forecasting System - Clarus
Major Initiatives > Emergency Transportation Operations
Other Program Activities > Amber Alert
Other Program Activities > Rural ITS Deployment
DMS, CMS, VMS, Changeable Message Signs, Variable Message Signs