Best Practices in Traffic Operations and Safety: Phase II: Zig-zag Pavement Markings

About the report:

The Washington and Old Dominion (W&OD) Trail is a 45-mile multiuse trail that spans the Virginia counties of Fairfax and Loudoun.  The more than 70 highway crossings of the trail create a significant potential for serious crashes between vehicles and bicyclists/pedestrians.  In an attempt to increase safety at two of the crossings, VDOT installed zig-zag pavement markings in Loudoun County where the trail crosses Belmont Ridge Road and Sterling Boulevard. 

This study assessed the effectiveness of the zig-zag pavement markings.  Effectiveness was defined as: (1) an increase in motorist awareness in advance of the crossing locations; (2) a positive change in motorist attitudes; and (3) motorist understanding of the markings.  Motorist awareness was assessed by before and after speed studies.  Motorist attitudinal changes were assessed through a survey targeting motorists, pedestrians, and bicyclists familiar with the markings.  The survey was distributed via links posted on the Loudoun County government office website and electronic newsletters distributed by the Broad Run and Sterling District supervisors’ offices (respective districts for Belmont Ridge Road and Sterling Boulevard).  Links were also distributed to bicycle clubs operating throughout the Northern Virginia area.  Motorist understanding was assessed through a hand-out survey in a different region of the state that targeted motorists unfamiliar with the zig-zag marking installation in Loudoun County.  

The study found that the markings installed in advance of the two crossings heightened the awareness of approaching motorists.  This was evidenced by reduced mean vehicle speeds within the marking zones.  Further, the majority of survey respondents indicated an increase in awareness, a change in driving behavior, and a higher tendency to yield than before, and the markings had a sustained positive effect on speed reduction.  The study also found that motorists have limited understanding regarding the purpose of the markings, and users of the W&OD Trail and motorists are confused regarding who has the right of way at the crossings.

The study recommends that (1) VDOT’s Northern Region Traffic Engineering Division lead an effort to recommend to the Federal Highway Administration that zig-zag pavement markings be included in the Manual on Uniform Traffic Control Devices; (2) the National Committee on Uniform Traffic Control Devices adopt as guidance the zig-zag pavement marking design parameters presented in this study; (3) VDOT continue to re-mark and maintain the zig-zag pavement markings at both test locations; (4) VDOT monitor and collect data on crashes at both locations for a 3-year period; and (5) a  review of the Code of Virginia be undertaken with respect to those sections of the Code having to do with trail users on multiuse pathways and their obligation to comply with non-signalized traffic control devices. 

When the costs of installing zig-zag pavement markings are compared to those of other safety countermeasures and the same effectiveness with respect to crash avoidance is assumed, the benefits of the zig-zag pavement markings far exceed those of a “do nothing” approach and those of the other countermeasures.  For example, if two evident injury crashes were avoided over a 5-year period, the monetary benefits associated with the installation of zig-zag pavement markings would be approximately $91,000 compared to approximately $58,000 for advance flashing beacons; overhead flashing beacons would have a monetary disbenefit (cost) of approximately $7,000.

Authors