| Roadway | 2003 Volume |
2030 Projection |
|
| Jamieson Canyon (Hwy 12) at Solano County Line | 44,566 | 58,000 | |
| Hwy 29 south of South Kelly | 44,391 | 62,000 | |
| Hwy 29 north of Hwy 12 | 43,159 | 95,000 | |
| Hwy 29 south of California | 29,321 | 38,000 | |
| Hwy 29 north of Zinfandel | 23,154 | 26,000 | |
| Hwy 29 south of Larkmead | 14,865 | 24,000 | |
| Hwy 121 at Circle Oaks | 2,753 | 22,000 | |
| Hwy 121 to Sonoma | 31,517 | 34,000 | |
| Silverado Trail | 9,282 | 22,000 | |
| Hwy 128 - east county | 11,727 | 15,600 |
Source: General Plan Traffic Study, 2006
If traffic is expected to more than double on Silverado Trail, what would happen if Angwin added another 1000 homes? Assume conservatively that only one person from each home uses the trail each day to get to and from work (hint: there aren't going to be 1000 new jobs created in Angwin) and you have the full increase for several years just from Angwin. Then add trips from contractors, deliveries, friends of the residents, kids going to St. Helena High School, shopping trips, and that many homes will have two wage earners commuting and think of the impact. At that point, they won't even be able to get to the Trail because Howell Mountain Road will be a parking lot. If people have trouble getting through main st St. Helena now during peak times, what would it be like with even a few hundres extra vehicles from Angwin?
Note that the original document has a "percentage increase" column that isn't the percentage change in traffic over the entire 27 year period, nor is it the yearly increase. Since I'm not sure what the calculation is, I've removed the column.