The effects of a reversible lane deployment in Roswell, Georgia are emphasized when the system is non-operational for maintenance during peak periods.
Roswell, Georgia, United States
NCHRP Synthesis 447: Active Traffic Management for Arterials
Summary Information
Active traffic management (ATM) is the adaptation of facility configuration and controls in response to or anticipation of variations in demand, incidents, and weather to optimize facility operation. The objective of ATM strategies on arterials is to maximize cost-effectiveness of the facility. The purpose of this synthesis was to document the state of the practice associated with designing, implementing, and operating ATM on arterials. This was accomplished through a literature review of advanced ATM methods for arterials and an in-depth telephone survey of agencies that had indicated through a pre-screening process that they had a high degree of knowledge and experience implementing ATM on their arterial streets.
Reversible Lane Deployment
Roswell, GA has used reversible lanes on a 1-mile corridor of South Atlanta Street (State Route 9) between Marietta Highway to Riverside Road for over 30 years. This corridor is configured as a three-lane facility with a reversible center lane. State Route 9 and US-19 are the major routes crossing the Chattahoochee River connecting the northern Atlanta communities with downtown Atlanta. The State Route 9 corridor is mainly a four-lane arterial facility, except the reversible lane corridor. A number of historic places along the road made it difficult to widen the road.
Reversible lanes are denoted with overhead illuminated signs. Signs are above each lane, with the outside lanes showing a static arrow so drivers know it is always available for that direction. The center reversible lane shows a red X or a green arrow, depending on the time of day and which direction is using the reversible lane. When the reversible lane changes direction, the system closes the reversible lane for all directions of travel. After a 5 minute clearance interval, the system reopens the lane for the reverse direction.
Lessons Learned
Deploy reversible lanes on arterial streets to improve capacity in the peak direction, but note that it may yield higher collision rates.
- There is improvement to capacity in the peak direction. The reversible lane adds capacity for the direction it is operating in. The city experiences major backups when the reversible lane system is non-operational versus when it is.
- Higher collision rates. This section of SR-9 has a lot of horizontal curvature, in addition to the reversible lanes, yet it was found that collision rates were higher than for similar facilities without reversible lanes.
