When analyzing roads, intersections, and traffic flow, engineers face a common challenge: vehicles are not all the same. A car, a motorcycle, a truck, and a rickshaw each take up different amounts of road space, move at different speeds, and influence congestion differently. To solve this, transportation engineers use the Passenger Car Unit (PCU) — […]
Annual Average Daily Traffic (AADT) is one of the most fundamental measures in traffic engineering and transportation planning. It represents the average number of vehicles that travel on a roadway segment each day over the course of an entire year. Put simply, it is a way to smooth out traffic variations across weekdays, weekends, and
Why Roads Must Adapt to a Changing Climate Roads and highways form the backbone of global transport networks. Yet, they are increasingly vulnerable to the impacts of climate change—flooding, extreme heat, erosion, and storm damage. As weather patterns intensify, traditional road designs are no longer sufficient. Engineers and planners must now integrate resilience strategies to
What is an ESAL? ESAL Formula Where: Typical Load Equivalency Factors (LEFs) (based on AASHTO & typical LEFs) Vehicle Type Axles Typical Load (kips per axle) Approx. ESAL per Pass Passenger Car (sedan) 2 2–3 0.0004 Pickup / SUV 2 3–4 0.001 Delivery Van (2-axle, light) 2 4–5 0.005 Single-Unit Truck (2-axle, 6-tire) 2 6–9
Sight distance is one of the most important considerations in road design. It represents the length of roadway visible to a driver, ensuring there is enough distance to perceive, react, and stop safely when encountering obstacles or conflicts. Inadequate sight distance can lead to unsafe conditions, higher crash risks, and poor traffic flow. This reference
When planning a new road, street, or highway, one of the most important decisions you’ll face is whether to use flexible or rigid pavement. Each has its advantages, costs, and ideal use cases. Choosing the right type of pavement can save millions in construction and maintenance over the project’s lifecycle. In this post, we break
In road design, traffic load isn’t just about how many vehicles pass each day — it’s about how much stress those vehicles place on the pavement over time. That’s where ESALs come in. If you’re involved in pavement design, planning, or construction, understanding Equivalent Single Axle Loads (ESALs) is essential. This article explains what ESALs
