2020 Green Wave

Elk Grove Blvd, Laguna Blvd, and Bond Road Traffic Signal Synchronization

On Monday, February 3rd, 2020 the City of Elk Grove implemented new traffic signal timing plans on Elk Grove Blvd and Laguna Blvd/Bond Rd. between Bruceville Road and Elk Grove-Florin Road. These traffic signal changes are intended to reduce congestion and travel times along these major east-west thoroughfares. In short, the signals were re-timed so that vehicles traveling east or west at the posted speed limit will have a greater probability of getting green lights. In order to accommodate the signal coordination, the total traffic signal cycle length was increased, and the timings were adjusted to favor the east/west through movements on 27 traffic signals. While this provides much needed congestion relief on the mainline, it can cause motorists on the side streets (north/south), or those turning left, to have to wait several seconds longer than before. This is the necessary tradeoff in order to provide the green time needed to coordinate the signals in the east/west direction.

The changes included implementing four different time of day coordination plans, as listed below, that required 90 new timing plans.

  • Weekday morning (6:00am to 10:00am)
  • Weekday midday (10:00am to 3:00pm)
  • Weekday evening (3:00pm to 8:00pm)
  • Weekend (10:00am to 3:00pm)

When the coordination plans are not in effect (i.e., 8:00pm to 6:00am weekdays) the traffic signals default to their normal operation, with priority given to the east/west direction and allocating green lights based on the vehicle detection sensors.

Initial Results

Travel time data was collected for the corridors before and after implementing the new timing plans. The results are summarized in the tables below. In short, we are seeing a reduction in travel times in all but one scenario, with the biggest travel time reductions occurring during the evening in both eastbound directions, during the morning in the westbound directions, and during midday again in the eastbound direction. Note that this is the first time the signals on Elk Grove Blvd. east of Hwy 99 have been coordinated.

Morning Travel Time (in minutes)

Location September 2019 February 2020 Difference
Elk Grove Blvd East Bound 7.7 7.7 0
Elk Grove Blvd West Bound 7.2 6.1 -1.1
Laguna/Bond East Bound 8.2 7.6 -0.6
Laguna Bond West Bound 7.5 6.1 -1.4

Evening Travel Time (in minutes)

Location September 2019 February 2020 Difference
Elk Grove Blvd East Bound 9.9 7.4 -2.5
Elk Grove Blvd West Bound 9.5 8.3 -1.2
Laguna/Bond East Bound 13.6 10 -3.6
Laguna Bond West Bound 10.3 9.2 -1.1

Midday Travel Time (in minutes)

Location September 2019 February 2020 Difference
Elk Grove Blvd East Bound 9.9 6.9 -3
Elk Grove Blvd West Bound 7.9 7.4 -0.5
Laguna/Bond East Bound 7.9 6.5 -1.4
Laguna Bond West Bound 9.1 8 -1.1

Issues Still Being Addressed

While implementation has yielded improved travel times, there are still some kinks to work out that can improve results further. There are two outstanding issues that are being addressed.

  1. Coordination disruptions. There are several signals that frequently drop out of coordination, disrupting the timing. When this happens it can take several cycles for the system to recover and for these intersections to get back in coordination. This is typically caused by emergency vehicle preemption, which forces the traffic signals to turn green. However, have experienced a higher than expected dropout rate due to signal controllers malfunctioning. Staff have been working with the signal controller manufacturer to repair the malfunctioning controllers, at no cost to the City. All malfunctioning traffic controllers were repaired as of 2/26/2020.
  2. Refinements to the traffic signal coordinating plans. We have been continuously monitoring the effectiveness of the plans and have been making minor adjustments based on our observations. As a continuation of this process, staff have worked with its traffic engineering consultants to develop updated signal timing plans for both corridors that are intended to maintain the travel time improvements in the east/west direction and provide some relief to the north/south and left turn movements. The new timing plans for Laguna/Bond were turned on 2/26/2020, while implementation on Elk Grove Blvd will is scheduled for 3/5/2020.

Next Steps

Staff will be bringing a list of potential infrastructure changes to the Council for consideration no later than April. These changes will consist of physical improvements to the intersections that will further increase the performance of the signal coordination by either allowing us to reduce signal cycle lengths and/or reallocate time to other movements at the intersection. Improvements would range from lower cost items such as removing a crosswalk at one leg of an intersection, changing the phasing at an intersection, and eliminating U-turns, to more costly projects such as extending storage for left turns or adding right turn lanes. The staff report will include an analysis and summary of the benefits gained from implementing the various improvements.

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