Warning lights on channelizing devices
Maryland State Highway Administration does not typically use warning lights on drums. Only in very rare instances would it do so, for example, if the roadway curves in one direction and a series of telephone poles parallel to this roadway diverges from the roadway at some point and motorists might try to follow the path of the telephone poles. In a case like that, Type C Steady burning warning lights on drums would emphasize the roadway curving.
Maryland found out that warning lights require a lot of maintenance. Batteries have to be replaced periodically. In the cold weather winter months, the batteries have to be replaced much more frequently.
Workers who service lights may disrupt traffic while performing maintenance, especially if no space is available to pull the work vehicle off the roadway to perform this maintenance task.
Performing maintenance of lights (especially at night) can put workers in danger.
Maryland does use Type A flashing warning lights only on Type III barricades where the roadway is closed.
Maryland uses Type A flashing warning lights for signs on roadways where the prevailing travel speed is over 40 mph. However, no warning lights are used on signs if they are fluorescent orange high-performance wide-angle sheeting. This sign sheeting is used on most expressways and freeways and will be expanded to all roadways after December 2003.