Why aren't the signals timed so I never have to stop?
Closely spaced signals, intersections where major streets cross, and changing traffic volumes all add to the difficulty of minimizing stop and go traffic for all directions of travel. Fire trucks and ambulances have special lights that change the signal to green for them, and this disrupts the timing patterns at intersections for as much as ten minutes.
Why do I have to wait when there's no one coming?
Older signals don't have the necessary equipment to detect when cars are approaching, so green times are set longer. Minor streets get less green time than major streets so that the higher volumes can keep moving and don't build up. Pedestrian crossing times (Walk and Don't Walk) may require longer green intervals. A group of cars may come from one direction, then there might be a gap before cars arrive from the other direction.
Why don't I always get a left turn arrow?
Left turn arrows take green time away from heavier through movements. Left turns can usually be made in gaps in traffic. Left turn arrows are sometimes turned off during lower volume times of day when the turns can be made through existing gaps.
Will a traffic signal reduce crashes at our intersection?
Traffic signals don't always prevent collisions. Typically, when a signal is installed, the total number of crashes increases, but the severity decreases. Where signals are used, the most common result is a reduction in right-angle collisions, however, rear-end crashes are prone to show an increase. Signals also may give pedestrians a false sense of security.
When are traffic signals installed?
Traffic signals are intended to facilitate the orderly movement of traffic. As the most restrictive form of traffic control, traffic signals are installed only where less restrictive signs or markings do not provide a sufficient level of control. Most intersections would not necessarily be improved or made safer by the installation of a traffic signal.
Unnecessary signals cause wasteful and annoying delays to the flow of traffic. They can increase traffic on the side streets as drivers seek alternative routes through neighborhoods. Excessive starting and stopping burns needless amounts of gasoline, resulting in pollution and economic loss. And as previously mentioned, they can increase the total amount of crashes at an intersection.
What are the official guidelines?
The City of Lincoln follows City policies and Nebraska State Law, which requires us to follow the national guidelines outlined in the Manual on Uniform Traffic Control Devices (MUTCD) . Traffic control devices include signal lights, traffic signs and markings. The MUTCD covers all aspects on the placement, construction and maintenance of every form of approved traffic control.
What are the installation criteria for traffic signals?
In determining the need for signalization, traffic engineers ask several standard questions about the intersection.
- Is the volume of traffic at the intersection such that a signal is needed to decrease congestion or confusion?
- Will the installation of a signal allow for continuous, uniform traffic flow with a minimum number of vehicle stops?
- Do a significant number of drivers on the side streets experience excessive delay in attempting to cross or enter the major streets?
- Does the intersection have a high number of pedestrians whose crossing can be made safer?
- Does the number of school children crossing at the intersection warrant special protection? If so, would a signal be the best solution?
- Will probability of occurrence in the number and type of reported collisions be significantly reduced by a signal?
In order to answer these questions, a traffic study by a qualified and experienced traffic engineer is required of the intersection. As part of the study, traffic volume levels and crash history are compared with established national standards for signalization. Intersections which conform to these standards or warrants are the best candidates for signalization.
Installation of a traffic signal typically costs between $60,000 and $120,000 per location. Factors that contribute to this cost include highly specialized control equipment and hardware that is needed, plus the extent of the system installed underground.
If you have any questions about Traffic Signals, please contact the City of Lincoln, Public Works Department - Engineering Services at 441-7711.