March 8, 2005 > Newark Traffic Control
Newark Traffic Control
In the last issue of the Tri-City Voice, we spoke with traffic management specialists at the city of Fremont. Jim Davis, city of Newark engineering specialist, spoke with the Tri-City Voice about how Newark approaches traffic signal placement and maintains traffic control.
TCV: How does Newark decide where to place traffic signals?
Davis: The main thing we follow is the Manual of Uniform Traffic Control Devices issued by the federal government. We used to use the CalTrans Traffic Manual issued by the state. They are both similar and contain "warrants' (justifications) for traffic signals. We evaluate a group of factors (traffic volume, correctable accidents, pedestrian access, etc.) to see if they meet the warrants. This is the technical study that is done when an intersection is being evaluated.
TCV: Who makes the final decision?
Davis: The city's engineer, Dennis Jones, will evaluate the study and decide if this should be presented to the city council for its approval.
TCV: Have there been many recent placements of traffic signals in Newark?
Davis: We have installed signals sporadically. In the city of Newark, we have approximately 40 traffic signals. Each signal runs independently. They are "on demand," sensing when traffic is present and act accordingly. Some rest in a green signal on a main street until cross traffic is detected.
TCV: What about bicycle traffic?
Davis: Most of our signals can detect bicycle traffic. If they are in a traffic lane, the detector loops will sense the bicyclist.
TCV: What triggers an investigation into installation of a traffic signal?
Davis: A new housing or commercial development may merit an investigation into anticipated increased traffic volume. Some signals may be installed based on recognition by staff or the public of increased traffic or cross traffic and a subsequent traffic study that meets warrants. New traffic signals on Cedar Boulevard and Lake Boulevard as well as Cedar Boulevard and Edgewater Drive were the result of staff and public awareness of the need.
TCV: Can a signal study result in other traffic measures?
Davis: We look at other possibilities as well. Stop signs, for instance, have their own set of warrants. The city council has adopted a traffic calming policy that outlines how staff responds to citizen complaints. One of the most common issues is speeding. We have a process to address these and may result in stop signs, speed bumps, better enforcement (police), speed signs and speed trailers (electronic speed indicators).
Newark requires that the installation of traffic control devices meet adopted warrants. We don't just put out stop signs anywhere if they do not meet engineering warrants. There is a reason for the warrants. If you put stop signs in a location that doesn't come close to meeting the warrants, people will not respect the stop signs; that can generate a worse problem. In these cases, we may use increased enforcement, speed signs, better centerline delineation and if, needed, speed bumps.
TCV: Does Newark coordinate stoplights with Fremont on Mowry Avenue near NewPark Mall? How do you handle increased traffic during the holidays?
Davis: We do not coordinate with Fremont signals. In the traffic engineering world, there is something called "levels of service." This indicates how well an intersection is functioning under heavy traffic. Sometimes you reach the total capacity of a roadway which cannot be addressed without major geometric improvements. At peak periods like the Christmas season around the mall area, there is more traffic than the roadway can handle no matter how you time the signal. There are too many cars coming from too many directions.
I am surprised that people insist on making the left turn into the mall from Mowry Avenue when they can go to Cedar Boulevard, turn left and enter the mall from a number of points on Cedar. Traffic is being looked at by consultants developing improvement plans for the mall. I do run a different "time of day" program increasing the maximum green light for the double left turn signal entering the mall during the holiday season.
TCV: Are signals programmed individually or through a central computer?
Davis: Each signal is programmed individually.
TCV: Can the fire department control signals?
Davis: There is emergency vehicle preemption on some signals. Detectors on the traffic signal arms respond to emitters on all fire emergency vehicles. Every new signal installed includes this system. Our goal is to eventually include all signals in Newark.
TCV: Can signals operate during a power outage?
Davis: We received grant monies a couple of years ago that allowed us to install a battery backup system at 12 major intersections. Signals will operate during an outage up to four hours. That has been helpful at intersections such as Cedar Boulevard and Thornton Avenue. During the last five to six years, we have retrofitted all our signals from incandescent lamps to LED lamps. LED look like little dots. They are very energy efficient. Installing these at an intersections cut energy consumption and cost by 60 to 70 percent. Lower energy consumption allows these lights to run on battery backup for substantial periods of time. When required, there is an uninterrupted changeover to the battery system.