Traffic Signal Upgrades
Description:
The City of Palm Springs is currently upgrading signals, poles, motion detection timing, and other equipment at 17 intersections as part of the Federal Highway Safety Improvement Program (HISP).
The Highway Safety Improvement Program (HSIP) is a core Federal-aid program with the purpose to achieve a significant reduction in traffic fatalities and serious injuries on all public roads. The HSIP requires a data-driven, strategic approach to improving highway safety on all public roads with a focus on performance.
In particular, a review of traffic collisions and accident data identified a large volume of collisions, all due to driver error, involving left turning vehicles failing to yield to opposing traffic, excessive high speed of opposing through traffic, and rear end collisions due to left turning vehicles immediately breaking to avoid a collision with opposing traffic and the vehicle following the left turning vehicle not prepared to stop in time. At these intersections during the 4-year period analyzed, a total of 218 collisions occurred.
The traffic safety measures that are a part of this project include protected left turn phasing to eliminate opportunities for drivers’ failure to yield to opposing through traffic (noted as an automobile right-of-way cause of accident), installation of latest updated technology for vehicle detection zones, and other miscellaneous improvements.
Project Locations: Map
- East Palm Canyon Dr & Smoke Tree Ln/Cerritos Rd.
- East Palm Canyon Dr & Farrell Dr./Barona Rd.
- East Palm Canyon Dr & Cherokee Way
- El Cielo Rd & Ramon Rd.
- Farrell Dr. & Tahquitz Canyon Way
- Farrell Dr & Baristo Rd.
- Gene Autry Trail & Via Escuela
- Indian Canyon Dr. & Racquet Club Rd.
- Lawrence Crossley Rd & Dinah Shore Dr.
- Paseo Dorotea & Ramon Rd.
- Sunrise Way & Racquet Club Rd.
- Sunrise Way & Amado Rd.
- Sunrise Way & Tahquitz Canyon Way
- Sunrise Way & Baristo Rd.
- Sunrise Way & Ramon Rd.
- Sunrise Way & Mesquite Ave
- Sunrise Way & East Palm Canyon Dr.
What this means:
This project will convert intersections with a protective/permissive left turn operation to a protected left turn operation. This is to eliminate driver error caused by automobile's failure to yield (in part due to excessive speeding of opposing through traffic) and will significantly reduce the chance of broadside (t-bone) crashes that can result in the most serious of injuries.
The additional left turn only phase will increase the time it takes the traffic signal to go through its cycle and will cause vehicles to wait at a red light for a longer period of time. However, this inconvenience will provide increased traffic safety and potentially reduce the number of accidents, especially those causing serious injuries or fatalities.
Please do not call the City to fix the traffic signal timing.
About Left Turns at Traffic Signals:
Traffic signals in the City are designed with three levels of control for left turning vehicles at intersections.
Permissive Left Turn
The permissive signal control uses a green light that allows for the driver turning left at the intersection to make the turn when there is enough distance, or gaps, with oncoming traffic to safely make the left turn.
Permissive traffic signal operation allows for shorter traffic signal cycle lengths due to the elimination of any protective left turn phases. This operation requires drivers use their judgement when turning left, to yield to opposing traffic, to safely determine the speed of oncoming traffic and to identify a gap on which to turn.
Protected-Permissive Left Turn
The Protected-Permissive signal control uses the permissive left turn operation in combination with a protected left turn operation and was implemented by the City at many intersections in accordance with State standards. The protected-permissive signal control operates by providing a protected left turn phase when enough cars are queued to turn left, or automatically at the start of a green phase, cycling to a permissive left turn phase allowing left turning vehicles to turn when it is safe to do so with oncoming traffic.
During the protected left turn phase, opposing vehicles are stopped by a red light, and left turning drivers are given clearance to turn on a green left arrow, that will cycle to a yellow left arrow, followed by a permissive green light. The permissive green light will then cycle through the traditional yellow and red phases to complete the cycle. Traffic signals with protected-permissive phases are identified with the 5-section signal lights as shown below.
Protected-permissive traffic signal operation requires a longer traffic signal cycle length due to the addition of the protected left turn phase in combination with a permissive phase. While this operation allows for many of the left turns to have a protected left turn arrow, it still requires drivers use their judgement when turning under the permissive left. They will need to determine when to yield to opposing traffic, safely determine the speed of oncoming traffic and identify a gap on which to turn. Studies have shown that the protected-permissive signal operation can have a lower volume of collisions than a traffic signal with only permissive operations.
Protected Left Turn
The protected signal control provides a dedicated left turn only phase, limiting the opportunity for a driver to turn left at only those times a green arrow is identified for the left turn lane(s). During the protected left turn phase, the opposing traffic is stopped by a red light until the left turn signal cycles through the yellow and red arrow. Then the opposing traffic will get a green light to proceed through the intersection while those wishing to turn left are stopped by a red arrow. Protected signals are often identified by the typical 3-section signal lights with a red, yellow and green arrow indicated over the left turn lane(s).
Protected traffic signal operations requires a longer traffic signal cycle as it provides a dedicated phase for left turn movements. Drivers wishing to turn left are required to wait through the traffic signal cycle until a green arrow is indicated. Studies have show that the protected signal operation can have the lowest volume of collisions due to the complete separation of left turning vehicles from opposing traffic.