Back Warning Sensors for Tow Plows, RB07-012, 2013

Backup warning system devices were evaluated to determine if they would alert winter maintenance snow plow drivers to obstacles directly behind the trailer and out of view of the driver when a unit is backed up. When the sensors on the back of the tow plow were covered with snow during plowing operations, the sensor would go off in the cab and continue going off, which would result in drivers turning the volume of the unit way down. One shop stated that the wireless transmitted signal would be hit or miss depending on the winter weather that they were operating in. The sensors on the back of the tow plow trailer would come in contact with salt brine and in this situation one of the sensors did go bad. The weatherproof box that was designed to keep the system waterproof did not fully keep the moisture out. It was found that the system did alert drivers of items behind the unit and there were no backup accidents reported during the research period.

On-Pavement Signing, 2014

Pavement marking legends are placed on the roadway to remind drivers of the speed limit or to slow down. Use of wording on the pavement surface is more dramatic than use of signing only, which can get lost in the clutter of a streetscape. On-pavement speed limit markings have been used to reinforce speed limits or to indicate a transition zone. For more on this topic by these authors, see also "Evaluation of Dynamic Speed Feedback Signs on Curves: A National Demonstration Project": http://www.trb.org/main/blurbs/172092.aspx

Vertical Delineation, 2014

Vertical delineators are intended to warn drivers of an approaching curve while providing them with a better appreciation of the sharpness of a curve. Drivers can then select an appropriate speed before entering the curve. Delineation can also provide continuous tracking information once drivers are within the curve to help position their vehicles within the travel lane while traversing the curve. The most common type of vertical delineation is post mounted delineators (PMDs). These devices are usually flexible or rigid posts with some amount of reflective surface mounted along the roadside to provide additional delineation. Another treatment that has been used is to provide additional delineation on chevron posts.