By David M. Greenwald
Davis, CA – The new proposed configuration for Mace seems like a reasonable arrangement—it eventually adds traffic lanes both north and southbound while still keeping bicycle lanes and protection for other modes of transportation intact.
While it was easy to point the finger at the road reconfiguration a few years ago for causing the traffic delays, especially in the pm on Thursdays and Fridays, in some respects the traffic impact started well before that and was the result of traffic congestion on I-80 as well—as traffic bypassing that congestion using Tremont Road to skirt around it and ending up pouring volumes of traffic on Mace.
As such the addition of travel lanes on Mace might help somewhat with congestion, but during those times when I-80 is at a standstill, only marginally so.
As the traffic engineer from Fehr & Peers noted back in 2019, “What we’re seeing it’s about a 10-minute difference.” So, by getting off at Dixon and instead of traveling east on 80, the vehicles are saving about 10 minutes of time.
And so there might be a problem here as he pointed out at the time: “Anything that we do along this corridor to make it faster to get up Mace from south of Montgomery all the way up to the freeway will potentially draw more traffic off of 80 onto Mace.”
The solutions they want are to help the local community get through Mace better, “but dissuade some of the regional cut through traffic that’s using Mace as a bypass for 80.”
This has been a point I have been trying to make for several years now—you can’t solve Mace by only addressing road capacity on Mace.
One big piece of that puzzle is outside of our hands—that is the I-80 corridor.
Last summer, for instance, the US Department of Transportation awarded an $85.9 million Infrastructure for Rebuilding America (INFRA) Grant to the Yolo County Transportation District and the California Department of Transportation’s (Caltrans) District 3 application to improve and expand 17 miles of the Interstate 80 and U.S. Highway 50 corridors in Yolo and Sacramento Counties.
According to Congressman Garamendi, “The $85.9 million in federal funding will be used to reduce congestion on Interstate 80 and U.S. Highway 50 by creating new managed lanes along 17 miles of highway.”
But of course that has the same risk as simply expanding capacity on Mace—you open up capacity and incentivize more traffic entering the roadway.
As Adrian Engel from Fehr & Peers pointed out, “some of the congestion can be mitigated with the solutions that we have, but all of it will not be mitigated.” The key is there will be “freeway congestion that causes queuing onto the corridor.”
He explained that he and his team got onto the freeway during peak time to validate that the freeway was not the fastest way to get from Dixon to the Causeway. Five of them traveled at the same time through different routes to see if the apps and maps and Waze “were telling us the true story.”
Traveling on the freeway was indeed the longest time. Some of the other routes “were definitely faster than the freeway.” The fastest they found was Highway 113 and County Road 29 to bypass the queue. They found that to be almost 15 minutes faster.
“There are multiple ways that can be used to bypass this freeway traffic,” he said. “The software that’s giving you these alternate routes is true and we have verified are actually faster. Ultimately the solution for this problem is going to fix I-80 and getting that traffic to flow better to keep cars on the freeway. Because if you fix Mace or do something to Mace, it may just cause traffic to go in other places.”
One of the solutions that the city has come up with in their Mace plan is to attempt to slow some of that traffic from Tremont entering Mace.
As a second phase, they will install a pilot project metering traffic light simulation at Tremont and Mace and 30 days later at Montgomery and Mace.
According to the city, “City will pay the costs. City and county will each independently determine whether or not to commit to a permanent project based upon factors such as traffic improvement, impact of the signal on residents and businesses and any unintended consequences.”
“For the Mace corridor, the integration of a signal to meter the flow of vehicles before they enter the corridor is crucial to eliminating cut-through traffic trying to skirt I-80,” Mike Webb explained. “The traffic modeling suggests metering is key. The current plans integrate pilot metering signals at two locations, Tremont and Montgomery, so we can test this in the real world before investing in a full permanent signal.”
This is probably the best we can hope for. The city is expanding capacity on Mace. The city is metering the traffic coming from Tremont. And CalTrans is expanding capacity on I-80.
Will that fix the traffic problems? Probably not. But it will mean that perhaps most days traffic congestion will not be a problem on Mace. We’ll see.