Special Route Restriction History - Route 175
Hopland Grade is a 12-mile segment of Route 175 between Routes 101 (PM 5.40 at 5.4 miles east of Route 101 in Mendocino County) and Route 29 (PM 8.19 at N. Jct Rte 29 north of Kelseyville in Lake County).
"No vehicles or combinations over 39 feet."
1979 - Correspondence requesting the removal of large vehicles from Hopland grade dates back to 1979.
1989 - Caltrans analyzed the geometrics on that route segment and designated it as "California Legal - Advisory" suitable for trucks with a kingpin-to-rear-axle (KPRA) length less than 30 feet; however, California Legal trucks with 40-foot KPRAs could still legally use the route.
1993 - The restriction process officially began when the California Highway Patrol (CHP) requested the prohibition of large vehicles from that segment of Route 175. Later that year, Caltrans District 1 completed a Route Study.
1996 - Caltrans District 1 completed an environmental study called "Initial Study for Truck Restriction of Vehicles with 4+ Axles." In the same year, Lake County held a public hearing.
1997 - Both the Board of Supervisors in Lake County and in Mendocino County approved resolutions supporting this restriction. The Caltrans Director approved the request.
1998 - The 39-foot vehicle length limit was imposed.