Two-Lane Highways

Abstract

Two-lane highways, which have one lane per direction, are unique operationally, since they may allow passing through the use of the opposing traffic stream. According to the US Federal Highway Administration [1], two-lane highway facilities represent about 97 % of the total highway system and for more than 65 % of the total nonurban vehicular travel in the USA. Hence, two-lane highways provide most of the primary interurban highway network as well as being the basis of the secondary highway and collector networks.

Problems

• 1. Conduct a literature review and document two-lane highway designs and traffic operational analysis methods around the world.

• 2. Using your favorite traffic simulator, analyze operations along a two-lane highway facility with EB demand equal to 1,540 vph and WB demand equal to 1,420 vph. Assume the facility is 2 miles long and is located on level terrain with no horizontal curves. There are 5 % heavy vehicles, and passing is allowed along the entire section. What is the estimated capacity of the facility according to the HCM 2010, and what is its capacity based on the simulation results?

• 3. Estimate the minimum passing distance for a vehicle with initial speed 50 mph and length 18 ft, if it is to pass a heavy truck with initial speed 25 mph and length 35 ft. Assume that the acceleration of the passing vehicle is 2.5 ft/s² and that the clearance distance d3 is 200 ft.

• 4. Conduct a literature review to assess capacity estimation at two-lane highways. How do these estimates differ across different parts of the world and for different designs?

• 5. Develop a passing algorithm flowchart and program it in your favorite microsimulation platform. State any assumptions you need to make in order to replicate passing maneuvers. How does your algorithm compare to the AASHTO Green Book-recommended passing sight distance values?

• 6. Conduct a literature review to assess the simulation of passing maneuvers and the associated gap acceptance models. Develop a recommended process for collecting relevant data to simulate passing maneuvers for various driver and vehicle types as a function of the geometric design characteristics of the two-lane highway.