A two-phase traffic signal is being designed for a standard four-leg intersection. The intersection has a total lost time ($L$) of $10 \text{ seconds}$ per cycle. Traffic surveys determine that the critical flow ratio ($y_1$) for Phase 1 (North-South) is $0.35$ and the critical flow ratio ($y_2$) for Phase 2 (East-West) is $0.40$. Using Webster's formula, calculate the optimum cycle length ($C_o$) for this intersection.

A weaving section of a rotary intersection has a width ($w$) of $12 \text{ meters}$, an average entry width ($e$) of $8 \text{ meters}$, and a weaving length ($l$) of $45 \text{ meters}$. Traffic counts indicate that out of $1,500 \text{ vehicles/hour}$ entering the section, $900$ vehicles cross the paths of others (weaving traffic), while $600$ vehicles do not (non-weaving traffic). Using the Transport and Road Research Laboratory (TRRL) empirical formula, estimate the practical capacity ($Q_p$) of this weaving section.

A standard four-leg intersection allows two-way traffic on all approaches. All movements (left, straight, right) are permitted. Calculate the total number of major conflict points (crossing, merging, and diverging) at this standard intersection, and compare it to the total conflict points at a three-leg (T-intersection) under the same two-way, all-movements-permitted conditions.

Two new highways are being built.

• Location A: The intersection of two massive interstate freeways (both high-speed, high-volume) in a rural area where land is cheap and plentiful.
• Location B: The intersection of a major freeway and a busy arterial road in a densely populated urban environment where right-of-way (ROW) acquisition costs are astronomical.

Recommend the most appropriate interchange type (Cloverleaf, Diamond, or Directional) for each location and justify the engineering choice.

An engineer proposes adding an exclusive "left-turn only" phase (a green arrow) to a busy two-phase intersection because drivers are complaining about waiting for gaps in oncoming traffic to turn left. While this will improve safety for left-turning vehicles, explain the negative impacts this change will have on the overall capacity of the intersection.