Cloverleaf and Diamond Interchanges: Advantages and Disadvantages

Did you know that the average American drives 13,474 miles a year? ⁱ That equates to over 1,000 miles a month and almost 40 miles a day! As a society that is always on the go, we rely on our roads to be constructed efficiently to get us to-and-from work, social gatherings, and school. 

If you aren't a professional civil transportation engineer, then you probably haven't put much thought into what makes our roads effective. From roadway grades to pavement, there are many factors that transportation engineers need to consider when optimizing driving routes. Interchanges are always a factor to consider; especially when drivers need to have the ability to transfer from one road to another. According to the Missouri Department of Transportation, "An interchange is a grade-separated intersection (one road passes over another) with ramps to connect them. [...] Interchanges are designed to fit specific local conditions and meet driver expectations." ii

Although there are many types of interchanges throughout America's roadways, cloverleaf and diamond interchanges are the most prevalent. ⁱⁱⁱ 

When an interchange needs to be constructed, transportation engineers need to consider factors such as cost efficiency, location, and volume. Learn more about the two most prevalent interchanges below: 

Cloverleaf 

By Vectorised by User:Sushant savla from the work by User:BotMultichill - File:Knooppunt klaverblad.png, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=73150655

This is a relatively popular interchange because it only requires one bridge that is constructed between the perpendicular and the leading routes. Construction of this interchange is relatively inexpensive because of this. 

A factor to consider when evaluating this interchange is the need for a large amount of land, as this interchange takes up a lot of space. Another disadvantage to this interchange is it can only serve a low capacity of traffic and because of this, cloverleaf interchanges are typically found on older roads in rural areas. 

Diamond

By RubySS, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=3165455

"The diamond interchange is the most common type where a major facility intersects a minor highway. The design allows free-flow operation on the major highway but creates at-grade intersections on the minor highway with the ramps." ⁱⁱⁱ Unlike the cloverleaf interchange, the diamond interchange is suitable for both rural and urban areas. The diamond interchange also doesn't take up much space, and therefore is relatively economical to construct. 

The main disadvantage to the diamond interchanges is the possibility of congestion. For example, if a car is attempting a left-hand turn after exiting another roadway, traffic may build up behind that car if the traffic on the cross road prohibits the car from turning at a reasonable time. This can cause traffic to back up the exit ramp and may even cause congestion on the original road the car was exiting from. 

References 

i. DiLallo, M. The Average American Drives This Much Each Year -- How Do You Compare? Retrieved from https://www.fool.com/investing/ general/2015/01/25/ the-average-american-drives-this-much- each-year-ho.aspx

ii. Highway Features. Retrieved from https://www.modot.org/highway-features-0

iii. Studies : About Interchanges. Retrieved from http://www.dot.state.oh.us/Divisions/ Engineering/Roadway/studies/ aboutinterchanges/Pages/default.aspx

"When Should I Begin Studying for the NCEES PE Exam?"

As an exam review course provider, we get the question, "When should I begin studying for the PE exam?" quite often. Since we get asked this question so often, we thought we would do some research. Did you know that the average exam applicant spends approximately 300 hours studying for the NCEES PE exam? 

While 300 hours may seem like a lot, it makes sense; the PE exam, no matter which discipline, asks extremely complex questions. Those who pass the PE exam become licensed engineers, and as engineers are responsible for the general public's safety, they need to understand complex engineering concepts. For example, exam applicants preparing for the PE Civil exam with a Transportation Depth need to understand the following topics: 

Breadth Topics 

• Project Planning 
• Hydraulics and Hydrology 
• Means and Methods 
• Geometrics 

• Soil Mechanics 
• Materials 
• Structural Mechanics 
• Site Development 

Depth Topics 

• Traffic Engineering 
• Horizontal Design 
• Vertical Design 
• Intersection Geometry 
• Roadside and Cross- Section Design 

• Signal Design 
• Traffic Control Design 
• Geotechnical and Pavement 
• Drainage 
• Alternatives Analysis 

When putting the 300 hours into consideration, how far in advance do typical exam applicants begin preparing for their exam? We dug a little deeper and conducted a survey. We found that a majority of survey respondents reported an average of 3-6 months was needed to sufficiently prepare. 

As the pencil and paper PE exams are currently 3 months away, we highly encourage those who have not begun studying to begin. By beginning the studying process now rather than later (in March or April), you'll be thanking yourself when you aren't forced to cram hundreds of hours of studying into the two weeks before the PE exam. 

A great way to study for the exam is to take an exam review course. School of PE offers PE Architectural, PE Chemical, PE Civil, PE Control Systems, PE Electrical, PE Environmental, PE Fire Protection, PE Industrial, PE Mechanical, and PE Petroleum exam review courses. Many Live Online courses for the upcoming pencil and paper exams begin this February, but to begin studying right away, School of PE offers an Ondemand option. 

Bundling options are also available. With our bundle option, you can even pay for the Ondemand course and later add the Live Online or Onsite class for only $300. This allows our students to start studying on their own now and then participate in a structured class that is scheduled closer to the date of the NCEES PE exam. 

What are you waiting for? Sign up to begin preparing today! 

The Benefits of Online Engineering Exam Prep Courses

Throughout the last few years, e-learning has become extremely popular. Once frowned upon and avoided, students began to become more attracted to online learning. Now, many universities offer online college courses, there are even degrees students can achieve completely online! Since the year 2,000, the online-learning industry has had a significant growth of 900%. 

As a review course provider, School of PE understands the benefits of online learning. Not only does online learning allow students to study anywhere, anytime, but it also increases lecture/ material retention rate and memory consolidation. Learn more in the infographic below: 

To help engineers prepare for licensure exams, School of PE provides Live Online courses. The Live Online courses are led by our experienced instructors and follow a traditional classroom structure. The advantage is that this classroom is virtual, and students can attend class from the comfort of their homes. This online platform goes beyond one-way learning and follows a structured study schedule to keep students on track. 

To registered for a Live Online course for your desired prep course, whether it be FE, PE, SE, or Surveying, please click here. 

References

Little-Wiles, J., Fox, P., Feldhaus, C., Hundley, S., & Sorge, B. Student Engagement Strategies in One Online Engineering and Technology Course. Retrieved from https://www.asee.org/public/conferences/20/papers/7674/download

Gutierrez, K. (n.d.). Facts and Stats That Reveal The Power Of eLearning. Retrieved from 

https://www.shiftelearning.com/blog/bid/301248/15-facts-and-stats-that-reveal-the-power-of- elearning