The City of San Diego is pushing for this road connection, we believe, because they feel it will improve traffic circulation overall in the City.  However, the very extensive traffic impact analysis prepared as part of the Quarry Falls environmental impact report, which was accepted and certified by the City, does not support that claim.

Some road segments and intersections get better with the connection, and some get worse.  Many have no change.  What we’ve done is look at how much the improvements get better and how much the detriments get worse, to try to reach a logical conclusion (rather than a political one).

There are hundreds of pages of traffic data in the Quarry Falls environmental impact report.  SMPG has summarized the results in a four page PDF, with the numerical tables as backup, and a summary map (which might not make sense if you haven’t read the explanation of V/C ratios in the four-page analysis).

Here are the most relevant pieces of that analysis for Serra Mesa:

Mission Center Road (from Mission Valley Road to the I-805 Overpass)  will be better with the Phyllis Place connection than without it, by about 30%.  And Murray Ridge Road (from I-805 to Mission Center Road) is better, but only by about 3% — it doesn’t really make a difference either way on that segment.

Other than that, every road in Serra Mesa is better without the Phyllis Place connection.  A LOT better. The Murray Ridge Road bridge over I-805 will be almost 120% worse with the road connection.  That’s an extra 15,000 cars per day on the bridge, and predicted freeway ramp meter delay increases of more than 90 minutes.

What are we getting in exchange for waiting an extra 90 minutes to get on I-805 (where there will now be another 4000 cars on the freeway)?  Mission Center Road does not get widened to two lanes at the top of the hill (they need that money to pay for the Phyllis Place connector).  The Mission Center/I-8 interchange does not get remodeled.    There’s a little less traffic on Mission Center Road, as previously discussed, and a few segments of Friars Road see about a 10% reduction in traffic.

A complete list of the differences in mitigation projects is here.

Read for yourself in the traffic analysis PDF (linked earlier), and see if you reach the same conclusion:

In conclusion, the data from the KOA traffic study clearly show that the Phyllis Place road connection would achieve only marginal improvement in only some parts of Mission Valley traffic flow and no significant change overall in Mission Valley or in the total study area. The Phyllis Place connection would, however, result in highly significant increases in congestion in Quarry Falls and Serra Mesa and overcrowding at the I-805 access point.

These negative impacts to Quarry Falls and Serra Mesa do not come with a mitigating benefit to the City, and so there can be no reason to approve the Phyllis Place connection.