Truck Accommodation Design Guidance: Designer Workshop (4364-2)

The number of trucks on many highways in Texas and across the nation has increased to the point that special or unique roadway design treatments may be warranted . Increases in truck traffic have resulted from increases in time-sensitive freight (e .g., just-in-time deliveries), the North American Free Trade Agreement (NAFTA), and until recently a robust economy . As particular corridors have becom e increasingly dominated by truck traffic, or in locations where truck traffic might reasonably be segregated, questions have arisen regarding accommodations and treatments that may be appropriate for those corridors to address issues caused by truck traffic . This research investigated the sensitivity of current Texas design practice to the unique operating characteristics of large commercial vehicles and determined threshold conditions under which design should reflect these larger vehicles . Findings indicate that serious consideration needs to be given trucks when the average annual daily truck traffic (AADTT) reaches 5000 trucks per day during the design period . When the design AADTT reaches 25,000 trucks per day, there may be justification for considering separated truck roadways with a minimum of two lanes in each direction. This research recommends that the Texas Department of Transportation (TxDOT) consider changes in the following design parameters in its Roadway Design Manual (and/or other appropriate documents) : stopping sight distance, intersection and channelization, lane width, shoulder width and composition, sideslopes and drainage features, traffic barrier, passive signs, and acceleration lanes .