Why the 241 Toll Road makes the argument for high speed rail

Lately, the Transportation Corridor Agencies, who own and manage CA-241 and certain other toll roads, have been using a new website to promote extending the 241 south. Of note is this particular claim:

Extending the 241 will ease traffic on Interstate 5 by creating an alternative route for the hundreds of thousands of motorists a day who travel between San Diego, Orange and Los Angeles Counties. Without the toll road, travel from the San Diego/Orange County border to Mission Viejo will take one hour in 2025. With the toll road constructed, the same drive on Interstate 5 will take 25 minutes and only 16 minutes on the toll road. The 241 is also expected to take pressure off Interstate 15, currently used by many driving from eastern Orange County into San Diego County. The 241 Toll Road will carry thousands of vehicles that would otherwise be clogging neighborhood streets and Interstate 5.

This is highly interesting and applicable to the high speed rail program and conventional intercity travel for Southern California. Such a level of congestion would make even the current Pacific Surfliner route significantly faster for travel from Orange County to San Diego as well as the high speed rail route (however, travel from Orange County to San Diego is liable to be faster along the current Surfliner route due to the backtracking to Los Angeles and inland route; currently Irvine to San Diego is comparable according to Amtrak schedule and CAHSR Trip Planner, upgrades currently in the works and reasonably foreseen by 2025 would put the Surfliner in the lead).

Given the previous failures of the 241 to extend south, as originally intended, and its lack of actual connection to Mission Viejo, it is doubtful that they will succeed in this current venture, and such high levels of traffic congestion and delays will occur. If, however, Orange and San Diego Counties are able to cooperate on expanding rail service, increasing average speed, and cutting delays, intercity and commuter rail should prosper well and take the place that the 241 cannot.