# Why are some highways concrete and others asphalt **URL:** \ **Category:** Factual Questions\ **Created:** [March 7, 2008, 4:15am UTC](https://boards.straightdope.com/t/why-are-some-highways-concrete-and-others-asphalt/440411 "2008-03-07T04:15:34Z")\ **Posts on this page:** 5\ **Page:** 2
**Author:** ![KlondikeGeoff](https://avatars.discourse-cdn.com/v4/letter/k/3e96dc/32.png) [@KlondikeGeoff](https://boards.straightdope.com/u/KlondikeGeoff)\ **Post date:** [March 8, 2008, 1:08am UTC](https://boards.straightdope.com/t/why-are-some-highways-concrete-and-others-asphalt/440411/21 "2008-03-08T01:08:42Z")
[QUOTE=BobLibDem] Good Lord, how old are you? [/QUOTE] I regret to say, 80. ---
**Author:** ![Civil\_Guy](https://avatars.discourse-cdn.com/v4/letter/c/d78d45/32.png) [@Civil\_Guy](https://boards.straightdope.com/u/Civil_Guy)\ **Post date:** [March 8, 2008, 1:45am UTC](https://boards.straightdope.com/t/why-are-some-highways-concrete-and-others-asphalt/440411/22 "2008-03-08T01:45:04Z")
I’ll throw in $0.02 here. Beyond the bigger issues mentioned, there are other imponderables. If the portland cement concrete (PCC) was not constructed properly, the cracks can look pretty jagged and unsightly, though the pavement is otherwise okay - so that’s a reason for putting asphalt over the concrete. Also, the AC arguably rides better. As mentioned, the AC takes a lot less time to construct, pretty important for reopening busy roads. Generally, PCC pavement can be thinner, so if there are pipelines close to the road surface (shouldn’t be, but stuff happens), that might be an argument for PCC. PCC holds its surface better, so that’s why streets are often constructed with PCC gutters. PCC is also good for spot locations that take a particular beating, like bus landings. === When constructed, PCC can be given a moderately rough surface, but over time, it can wear too smooth for traffic safety - at which time, the highway department can cut in grooves. === Who knew that pavement was so complicated? Or that so many of us have made a study of it? ---
**Author:** ![Hello\_Again](https://avatars.discourse-cdn.com/v4/letter/h/85e7bf/32.png) [@Hello\_Again](https://boards.straightdope.com/u/Hello_Again)\ **Post date:** [March 8, 2008, 3:50pm UTC](https://boards.straightdope.com/t/why-are-some-highways-concrete-and-others-asphalt/440411/23 "2008-03-08T15:50:52Z")
Only semi-related, but I was driving, in rural pennsylvania I believe, and started seeing all these signs – obviously placed by lobbying groups – about the concrete vs. asphalt debate. They said things like “Asphalt: smooth and quiet” and “Concrete kicks asphalt!” It was unusual passing through a pocket of people who obviously cared intensely about the subject. 🙂 ---
**Author:** ![Triskadecamus](https://avatars.discourse-cdn.com/v4/letter/t/b19c9b/32.png) [@Triskadecamus](https://boards.straightdope.com/u/Triskadecamus)\ **Post date:** [March 8, 2008, 5:03pm UTC](https://boards.straightdope.com/t/why-are-some-highways-concrete-and-others-asphalt/440411/24 "2008-03-08T17:03:05Z")
It would be wonderful to believe that government construction choices were made on the basis of engineering concepts. Sadly, the existence of legislators with brother’s in law in various industries probably has a lot more to do with it. Tris ---
**Author:** ![Quartz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/quartz/32/267_2.png) [@Quartz](https://boards.straightdope.com/u/Quartz)\ **Post date:** [March 8, 2008, 6:00pm UTC](https://boards.straightdope.com/t/why-are-some-highways-concrete-and-others-asphalt/440411/25 "2008-03-08T18:00:49Z")
[QUOTE=Plynck] If you’ve ever been driving on a bituminous concrete highway, and get that regular rhythmic “bump…bump…bump”, it is likely that bituminous was laid over concrete, and your wheels are feeling the expansion joints underneath. [/QUOTE] Ah, I’ve wondered about that from time to time. [Previous page](https://boards.straightdope.com/t/why-are-some-highways-concrete-and-others-asphalt/440411.md?page=1)