TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 519: The Renewal of Stormwater Systems Using Trenchless Technologies summarizes technologies used for the renewal of stormwater systems, including new, emerging, and underutilized trenchless methods, and identifies future research needs. Both trenchless replacement and trenchless renewal methods can reduce negative impacts associated with surface disruption by moving the work area outside of the travel lanes and concentrating the const...

TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 515: Practices for Preventing Roadway Departures identifies and summarizes practices being used by state departments of transportation (DOTs) to prevent roadway departure crashes and to identify the data-driven advantages and disadvantages of these practices. More than half of all traffic fatalities result from roadway departure crashes. This type of crash occurs after a vehicle crosses an edge line or centerline or otherwise leaves th...

TRB's National Cooperative Highway Research Program (NCHRP) has released a pre-publication, non-edited version of Synthesis 527: Resilience in Transportation Planning, Engineering, Management, Policy, and Administration. The report documents resilience efforts and how they are organized, understood, and implemented within transportation agencies’ core functions and services. Core functions and services include planning, engineering, construction, maintenance, operations, and administration. The informati...

TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 521: Investment Prioritization Methods for Low-Volume Roads documents current practices used by transportation agencies to make investment decisions about low-volume roads. Current transportation asset management practices for low-volume roads typically use asset condition, traffic, and safety metrics to prioritize investment decisions for preservation, maintenance, repair, and replacement projects. However, these metrics do not fully ...

TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 516: Tack Coat Specifications, Materials, and Construction Practices provides state agencies across the United States with guidance as they reevaluate their tack coat specifications, the materials they use, and the practices by which the tack coats are placed. Pavement thickness design assumes that pavement works together as one layer, rather than a stack of individual layers working independently. Tack coats function as bonding agents...

TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 514: Statewide and Megaregional Travel Forecasting Models: Freight and Passenger documents current practices and emerging trends with travel forecasting models. The report explores the motivation for and capabilities of statewide and megaregion models, options for extending them and challenges states face doing so, data requirements, how they are used and integrated with other models, institutional constraints, and emerg...

TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 512: Use of Fiber-Reinforced Polymers in Highway Infrastructure documents the current state of the practice in the use of fiber-reinforced polymers (FRPs) in highway infrastructure. The synthesis identifies FRP applications, current research, barriers to more widespread use, and research needs. The objectives of the study are to synthesize published literature on FRP materials in highway infrastructure and to establish the state of cur...

TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 511: Relationship Between Chemical Makeup of Binders and Engineering Performance documents the current practices of departments of transportation (DOTs) in the selection of the chemical composition of a binder used in pavement applications. The study provides information about the selection of binders and postproduction additives and modifiers, as well as corresponding engineering performance.

TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 513: Evolving Debt Finance Practices for Surface Transportation explores a variety of debt mechanisms and tools to finance transportation infrastructure investment. The amount of debt and frequency of issuance vary substantially across states. In most states, provisions included in constitutions or statutes (or combinations of the two) govern the level and form of debt issuance. As well, many states have formal policies that govern deb...

TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 510: Resource Allocation of Available Funding to Programs of Work explores the decision-making process in state departments of transportation (DOTs) and how they determine resource allocation among different programs. The report documents current processes, techniques, tools, and data used to evaluate and select funding allocations around the country.