Free Civil Transportation PE Practice Exam Problem: Stopping Sight Distance

A topic you might encounter on the Civil PE Transportation Exam is stopping sight distance (SSD). It may show up tied to vertical or horizontal alignment design problems.

It's important to solve practice questions related to sight distance, perception–reaction time, and driver braking behavior. Here is one to help you prepare for the Civil Transportation PE exam:

Problem

A two-lane rural highway has a design speed of 50 mph.Assume a perception–reaction time of 2.5 seconds, and a braking deceleration rate of 11.2 ft/s².

What is the required stopping sight distance (SSD) according to AASHTO design policy?

A. 400 ft

B. 425 ft

C. 475 ft

D. 500 ft

Answer: B. 425 ft ✅

Solution

The AASHTO Green Book provides the general formula for stopping sight distance:

Stopping Sight Distance Formula

Where:

• V = 50 mph

• t = 2.5 seconds

• f = 0.35 (typical design value for level roads)

• G = 0 (level grade assumption)

Rounded to the nearest design value → 425 ft

PE Exam Tips

When solving sight distance problems:

• Be familiar with where to find the stopping sight distance formula in the AASHTO Green Book. It's important to spend time before the exam learning where to find key formulas in your exam references books. This will save you valuable time on exam day. Less time searching for formulas means more time to work the PE exam questions.

• If the problem involves an upgrade or downgrade, adjust G accordingly: use positive G for upgrades and negative G for downgrades.

  
  

Keep Practicing

Sight distance questions on exam day can be fast points if you’ve solved practice questions related to this topic prior to exam day.

For more Transportation PE exam practice, check out my practice question bank. It is meant to mirror the difficulty of the exam and focus on high-probability exam topics.

Get the 20 Question Practice Bank