Long-Term Pavement Performance

SHRP/ LTPP was initiated in 1987 to produce a national database which would support studies which analyzed the performance of our most popular pavement types, maintenance/ rehabilitation strategies, and surface treatments. LTPP studies fall under two main headings: General Pavement Studies (GPS) and Specific Pavement Studies (SPS).

General Pavement Studies involve maintenance and rehabilitation treatments on existing pavements.

• GPS-1: AC over granular base
• GPS-2: AC over stabilized base
• GPS-3: Jointed Plain Concrete Pavement (JPCP)
• GPS-4: Jointed Reinforced Concrete Pavement (JRCP)
• GPS-5: Continuously Reinforced Concrete Pavement (CRCP).
• GPS-6: AC Overlay of AC Pavement
• GPS-7: AC Overlay of PCC Pavement
• GPS-8: Bonded PCC Overlay of PCC Pavement (eliminated)
• GPS-9: Unbonded PCC Overlay of PCC Pavement

Specific Pavement Studies involve building new test sections.

• SPS-1: Structural Factors for Flexible Pavements (Drainage)
• SPS-2: Structural Factors for Rigid Pavements (Drainage)
• SPS-1 and -2 were intended to study base, subbase, pavement type and thickness with a strong focus on drainage.
• SPS-3: Preventative Maintenance Effectiveness for Flexible Pavements
• SPS-4: Preventative Maintenance Effectiveness for Rigid Pavements
• SPS-5: Rehabilitation of Asphalt Concrete Pavements
• SPS-6: Rehabilitation of Portland Cement Concrete Pavements
• SPS-7: Bonded PCC Overlay of PCC Pavements
• SPS-8: Environmental Effects on Flexible and Rigid Pavements
• SPS-9: Field Verification of Superpave Mix Design

The current annual spending for the LTPP database is on the order of $15 million for data storage. There are approximately 1,500 test sections in the U.S. and Canada participating in the LTPP Study. California contains thirty-six test sections. Each State/Province DOT collects pavement condition data on a biannual basis and submits it to their Regional Data Manager. Six Regional LTPP Data Managers collect the condition data from their respective states, conduct pre-established quality control checks, and submit the data to the national database. Anyone in the transportation community can obtain data from the LTPP database, and is encouraged to do so. Since the database is so large, a preliminary interview is necessary to acertain the precise data needed to fulfill the request.