When designing ITS systems intended to convey critical messaging to drivers, transportation agencies must consider the requirements for each deployment, and make choices regarding more versatile, full matrix dynamic message signs versus more affordable blank out signs with limited messaging. Often blank out signs can provide all the messaging functionality needed at a fraction of the cost of full size DMS, and do not require advanced communication networks or other infrastructure required by signs with full messaging capability.
DMS vs. BOS
Feature, Benefit and Cost Savings Analysis
| DMS/ VMS | Blank Out Signs | |
|---|---|---|
| Display | Full Matrix, Full Color, Amber, Text, Graphics | Full Color, Amber, Text, Graphics |
|
Control |
DMS Controller w/central processor, remote software and communication network |
Dry contact closure(s), traffic signal controller (optional) |
| NTCIP Compliancy | Yes | Yes (optional) |
| Size & Dimensions | Any size, any dimension | Any size, any dimension, including custom design |
|
Power Consumption |
High power consumption due to number of components including LEDs and power supplies, and DMS controller. Power consumption typically 50% (variable) or greater compared to BOS. | Energy is needed only when a message is displayed. Energy efficiency is higher than DMS |
| Solar Power Capability | Limited to high-efficiency amber LED models only. |
Amber and full color models capable of being reliably powered by solar systems. |
| Price |
Price typically 50% or more (variable) compared to BOS |
Fraction of the cost of full matrix DMS. Cost savings increase with larger models. |
Blank Out Signs offer many attractive features when compared to traditional DMS. However, Blank Out Signs are limited in the number of messages or symbols that can be displayed (typically 1-6 messages per BOS), so they are best used in specific applications. Typical deployments utilize MUTCD symbols to regulate traffic, or display dedicated messages to get the attention of targeted drivers and convey warnings such as “Prepare to Stop” , “Over-height Vehicle Detected”, or “Truck Must Enter Weigh Station.”
Case Study Lane Management |
The Best Applications for Blank Out Signs are:
Typical BOS product lines offer a selection of pre-existing and pre-defined messages that have been utilized for several years. These are applicable in many circumstances; however utilizing only existing MUTCD symbols and pre-formatted messages strictly limits the functionality and versatility of Blank Out Sign technology. Effective BOS design allows the end user to adapt to specific needs and create new, customized messages in a large range of colors and sizes. Today’s technology allows Blank Out Signs to be customized within a large field of options, including large format highway applications.
SESA has completely remodeled the concept of BOS in order to provide several cost effective solutions for state and municipal agencies - a viable alternative to full matrix DMS when it is not necessary to display more than 3 to 4 messages or symbols. SESA designs and manufactures multi-phase BOS customizable for each project and client at any size and dimension. SESA’s design utilizes robust LED technology that allows its engineers to design a wide variety of symbols and text, and accommodate them within standard sizes or custom built housings. All signs meet MUTCD requirements and housings are built to comply with NEMA 3R standards. SESA’s multi-phase BOS are built without a polycarbonate panel, eliminating the phantom effect, which can distract drivers while still maintaining high contrast ratio. Several options are available, such as vehicle activation, remote control, and with or without visors. Consistent with all SESA products, these BOS were designed with high-energy efficiency and most can be solar powered.
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