The intersection of the southbound State Route 4 exit ramp at Balfour Road is the subject of recently voiced concerns by Brentwood residents. In order to respond, the City would like to provide clarification on this subject.
Due to previous resident concerns regarding traffic congestion at the Balfour Highway 4 off-ramp, the City of Brentwood initiated a traffic study in February of 2019. The traffic study indicates the largest volume of traffic, both in the morning and in the afternoon, travels eastbound on Balfour Road. Based on the recommendations by the traffic study, the signal timing was adjusted to improve the movement of eastbound Balfour Road traffic.
The Balfour Road exit ramp off southbound State Route 4 has three lanes, two lanes turning right to the west and one lane turning left to the east. The satellite photo above shows the results of the traffic study, which was conducted during a period of good weather when school was in session. The study preceded the impacts of the COVID pandemic.
Numbers in yellow show peak morning traffic counts, while numbers in white show peak afternoon traffic counts. Arrows indicate lanes and their directions.
Based on the traffic study of 2019, there is about twice as much traffic in the morning from the off-ramp making a right onto westbound Balfour Road than left traveling east on Balfour Road. The afternoon traffic is about the same traveling in both directions. Making additional lane or light timing adjustments at this time will exacerbate congestion for both eastbound and westbound traffic on Balfour Road.
The City understands that this is an ongoing concern for residents and is working diligently, within its power, to create smoother traffic flows through the intersection. The City continues to monitor this intersection as well as other high traffic intersections on Balfour Road and other City roads. Additionally, as part of the City!s Pavement Management Project later this year, the eastbound Balfour Road lanes are slated to be restriped to provide three lanes from Eagle Rock Way to SR-4 Westbound on ramp. This improvement will provide additional traffic relief to this intersection
Below are answers to some frequently asked questions regarding the Balfour/ SR-4 off-ramp.
Q1. Can the State Route 4 off-ramp lanes be modified to two left-turning lanes and one right turning lane?
A1. There are currently two right turn lanes and one left turn lane onto Balfour Road. Based on the traffic study, during peak traffic, more vehicles turn right onto Balfour Road than left. Changing the striping would increase off-ramp traffic congestion. SR-4 off-ramps are under the jurisdiction of Caltrans, which does not presently consider this intersection an issue. It is also important to note that morning traffic making a right to go west on Balfour Road (746) is substantially more than the afternoon traffic going left (571) or right (576).
Q2. Can the lanes be modified to change the middle striping to a right and left turn lane resulting in one left turn lane, one left/right turn lane, and one right turn lane?
A2. If the middle lane was restriped to a dual left/right configuration, it might help move more vehicles making a left onto eastbound Balfour Road. However, drivers waiting to turn left in the middle lane will restrict those who want to turn right in the middle lane when the signal is red. Given the much larger volume of morning traffic turning right, restriping the middle lane to a dual left/ right configuration will result in greater delays in the morning and additional backup on the ramp. This will also result in additional backup on State Route 4. Congestion would be shifted but not alleviated. Furthermore, the off-ramp is under the jurisdiction of Caltrans, which will not approve any intersection striping modifications that will result in traffic backing up onto the freeway.
Q3. Can an additional lane be added to the off-ramp to create two left-turn lanes and two rightturn lanes?
A3. An additional lane can be added, but this would be a Caltrans project, not a City project. Since southbound traffic on State Route 4 over Balfour is not currently impacted by any backups, it is highly unlikely that Caltrans would agree to add a lane at this time.
Q4. Can the stoplight at the off-ramp intersection be adjusted to move more left-turning vehicles during peak hours to alleviate backup?
A4. The traffic signal timing can be adjusted to move more left-turn traffic from the off-ramp, but that would exacerbate congestion for both eastbound and westbound traffic on Balfour Road. The negative impact on the larger Balfour Road traffic would be much greater than the benefit to the lesser traffic flow on the off-ramp.
Q5. What will happen to the bike lane on Balfour Road between Eagle Rock Way and SR-4 west entrance?
A5. Through the City’s Pavement Management Project, the City is able to restripe the current Balfour Road lanes to provide three lanes from Eagle Rock Way to SR-4 Westbound on ramp and maintain a five feet wide bike lane