College - Author 1
College of Architecture and Environmental Design
Department - Author 1
City and Regional Planning Department
Date
5-2022
Abstract
This report covers the third study of fire evacuation in Cambria conducted by Dr. Cornelius Nuworsoo, professor of City and Regional Planning at Cal Poly San Luis Obispo. It is a follow-up to evacuation analyses conducted in 2019 for two parts of Cambria – areas south of Fiscalini Ranch and West of Highway 1, and areas east of Highway 1. With this study, Cambria now has analyses for all of Cambria under scenarios for different potential evacuation areas and alternate evacuation routes. Grant from CalFire funded the studies.
The new evacuation assessment, like the earlier ones, is designed to model the traffic movement that would occur during the rapid evacuation of large parts of Cambria during a major wildfire emergency. As with the other studies, it assumes that residential units and visitor lodgings are fully occupied, and that each household would evacuate with two vehicles, on average. All vehicle types in the traffic stream are converted to passenger car equivalents to account for buses, trailers, recreational vehicles, and commercial trucks in the traffic stream. Trucks count for three passenger cars and RVs for two.
It further assumes that through traffic on Highway 1 would be at normal levels before additional traffic is generated by evacuation from Cambria. This assumption adds the equivalent of 500 passenger cars on Highway 1 during the period of evacuation. Only southbound evacuation is modeled in all scenarios.
Note that this analysis, though assuming maximum traffic, is not able to predict the potential for other factors to impede evacuation, such as poor visibility due to smoke, nighttime conditions or fallen trees, stalled cars, and other potential obstructions.
In addition to scenarios based on using Highway 1 in its normal two-lane configuration (with one lane each southbound and northbound), this study also analyzes scenarios with alternate evacuation routes, as well as a second southbound lane added to Highway 1 from Ardath Drive to Highway 46.
One alternate route is the existing emergency access road across the Fiscalini Ranch Preserve from Seaclift Estates to Marine Terrace. The other is a possible emergency access route from Marine Terrace to Highway 1 south of Highway 46. Labeled the “Beach Road” in the study, this route would follow the existing four-wheel-drive track through the Norris Rancho Marino Preserve and other properties to an existing private road, Harmony Ranch Road, which serves several residences on the coast and joins Highway 1 south of the Highway 46 junction. It is important to note that, at this point, public agencies have not made arrangements with the property owners for use of the route, nor have they secured funding to improve it for passenger-car travel.
The study analyzes these five new scenarios:
- Evacuate Park Hill and Moonstone Beach areas toward the south using one southbound lane on Highway 1.
- Evacuate Cambria west of Highway 1 (Lodge Hill, Marine Terrace, Park Hill and Moonstone Beach) toward the south using two southbound lanes on Highway 1 from Ardath Drive to Highway 46.
- Evacuate all neighborhoods toward the south using two southbound lanes on Highway 1 from Ardath Drive to Highway 46.
- Evacuate Park Hill and Moonstone Beach toward the south across the existing emergency access route on the Fiscalini Ranch Preserve, continuing through Marine Terrace to the end of Ardath Drive, then on to Highway 1 via the Beach Road.
- Evacuate both Lodge Hill and Marine Terrace toward the south using two routes: Highway 1 with one southbound lane, and the Beach Road to Highway 1 from the end of Ardath Drive in Marine Terrace.
In Scenario 5, the evacuation traffic would be divided along a line running northwest to southeast along Trenton Ave. and Norwich Ave. in lower Lodge Hill. Residents to west of that line would take the Beach Road route. Those to the east would evacuate via Highway 1.
In addition to these five scenarios, the study includes results (Scenarios 6 & 7) from the two previous studies, as well as modeling (Scenario 8) for all neighborhoods. Scenario 8 incorporates data from all three of the studies assuming the worst possible scenario of evacuating the entire Cambria community via a single southbound lane on Highway 1.
Among its key findings, the new study shows that an added southbound lane on Highway 1 from Ardath Drive to Highway 46 -- the “critical segment” on which all traffic would have to travel --would not have a significant impact on overall evacuation times.
For instance, the evacuation of all Cambria neighborhoods using two southbound lanes between Ardath and Highway 46 (Scenario 3) would take the same total time (6.8 hours) as full evacuation with one southbound lane only (Scenario 8). Travel time on that critical and final segment of Highway 1 would be half as long (albeit at nearly three times the hourly capacity of the highway in the southbound direction) in Scenario 3, but time spent reaching that final segment would negate the advantage of the two-lane option. Extending the two-lane option further north (see recommendations, below) would be at least a partial solution to this problem.
Also, using alternate routes – the Fiscalini Ranch emergency road and the proposed “Beach Road” from Marine Terrace to Highway 1 south of Highway 46 – would not offer a significant advantage over Highway 1 in evacuation of the Park Hill and Moonstone Beach neighborhoods. (See Scenarios 1 and 4 in Table 1).
On the other hand, the “Beach Road” option would substantially improve evacuation times from Marine Terrace and Lodge Hill (west of Highway 1) if traffic from that area were split between the Beach Road and Highway 1 (Scenario 5). Total evacuation time would be 1.8 hours, in contrast to over 4 hours as modeled in the 2019 analysis of this area.
The study’s results are summarized in Table 1 of the report, with additional information in Tables 2, 3 and 4. In conclusion, the study recommends:
- Establishing the Beach Road as an additional exit route.
- Designating the Beach Road for use by those in the southwest area of Cambria (western Lodge Hill and Marine Terrace).
- Widening and strengthening shoulders on Highway 1 to enable an improvised second southbound exit lane during emergencies.
- Extending the improvised second southbound lane further north on Highway 1, ideally as far as the intersection with Cambria Pines Road.
Document Type
Report
May 1, 2022.
URL: https://digitalcommons.calpoly.edu/wuifire/1