For those looking to delve further into provision of frontage roads in Texas, these may be of interest:
Kara M. Kockelman et al.,
Frontage Roads in Texas: A Comprehensive Assessment (FHWA/TX-01873-2) (2001):
"Moreover, the roadway geometry associated with frontage roads in other states was in many cases quite different from typical Texas designs. Frontage roads where development was allowed to occur on both sides of the roadway was a design characteristic shared by several states, generous ramp-to-signal distances were required by several policy guidelines, and development adjacent to the ramp-frontage-road interface to prevent dangerous weaving maneuvers was generally much more restricted than in Texas. While not every strategy given by a state DOT will apply to Texas, new and rehabilitated roadways within Texas may achieve significant operational and safety advantages by utilizing some of the techniques proven successful in other areas of the United States."
"The analyses presented here represent avenues of study not previously attempted. The momentum of frontage-road construction in the state of Texas dates back to before construction of the interstate highway system, and many may argue that it gave rise to undesirable roadway operations and land development within the state. It is hoped that these results, in addition to efforts by other researchers, will assist in constructing a solid, formal policy for Texas to follow in providing access along its new and existing freeways in the decades to come."
Charles Pinnell and Paul R. Tutt,
"Evaluation of Frontage Roads as an Urban Freeway Design Element",
Highway Research Record 9 (1963):
"In view of the effect that the presence or absence of frontage roads has on the cost of right-of-way, the construction of a frontage road system will usually result in a lesser overall cost for the entire facility."
The contrast in perspectives tells its own story--Pinnell and Tutt, writing during the era of first construction of the Interstates, essentially argue that savings in access rights at least reimburse the cost of constructing frontage roads. Kockelman et al. are more concerned with the operational and cost issues of managing a mature system, and essentially recommend that frontage roads be subject to some form of access management if they are provided at all. (2001 was also the year the Texas Transportation Commission passed Minute Order 108544, directing abandonment of the policy of building frontage roads by default.)