When designing intelligent transport systems (ITS) for conveying critical messages to drivers, transportation agencies must consider the requirements for each deployment, and make choices regarding more versatile, full-matrix dynamic message signs (DMS) versus more affordable blank out signs (BOS) with limited messaging.
Often BOS 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.
BOS offers many attractive features when compared to traditional DMS. However, BOS signs are limited in the number of messages or symbols that can be displayed (typically one to six messages per BOS), so they are best used in specific applications. Typical deployments utilise 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.’
The best applications for blank out signs are:
- Traffic regulation with manual on uniform traffic control devices (MUTCD), such as ‘no right turn’, and ‘no entry’
- Lane control sign (Red X, Green Arrow)
- To prevent a truck from entering a low tunnel (‘danger / overheight’)
- To warn drivers when a road is flooded: (road under water / detour’)
- To guide trucks after checking their weight ; (‘truck must enter weigh station / truck pass-by weigh station’)
- To indicate ‘open / closed’ to a gate entrance or lane
- BOS can be vehicle-activated. When a vehicle arrives at a pre-defined distance to the BOS, it lights or flashes or alternates several symbols. It is ideal to reduce speed for example when approaching a dangerous curve or dangerous traffic pattern
Typical BOS product lines offer a selection of pre-existing and pre-defined messages that have been utilised for several years. These are applicable in many circumstances; however utilising 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, customised messages in a large range of colors and sizes. Today’s technology allows BOS to be customised within a large field of options, including large-format highway applications.
SESA has completely remodelled 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 three to four messages or symbols. SESA designs and manufactures multi-phase BOS customisable for each project and client at any size and dimension.
SESA’s design utilises 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.
