Driveway Culvert width

olllotj · Apr 28, 2015

I'm building a new driveway on my property, and the Excavator suggested 40' of culvert at the road. Is it crazy to go so wide? I do have trailers, have Tractor trailers deliver occasionally..

davesl708 · Apr 28, 2015

I would go at least two feet wider than the driveway on each side. Always better to have the entrance to the drive wider than the drive. Long loads will need the extra room to make the turn without dropping off the road. Nothing more aggravating than a crushed culvert pipe when a large truck drops on the pipe.
If I am not mistaken culvert pipe comes in 20 or 40 ft. lengths. Anything in between would have to be cut to size.

aczlan · Apr 28, 2015

olllotj said:
I'm building a new driveway on my property, and the Excavator suggested 40' of culvert at the road. Is it crazy to go so wide? I do have trailers, have Tractor trailers deliver occasionally..

This is in a ditch on the side of the road? 40' would be a little wide for car traffic, but if you have much semi traffic at all, they will thank you for it.
40' will give you 30-35' of usable driveway (depending on the depth), will let you mow that area much easier and reduce the risk of ending up in a ditch while clearing snow in the winter. ... We had a 20' culvert out back (between fields) and it was mighty narrow when trying to cross with a tractor and wagon (or baler, etc, etc and those track better than a semitrailer). We added another 10' when we tore out some culverts at another location (5' on each side) and it is very easy to cross now.

Aaron Z

olllotj · Apr 28, 2015

Yes, it is sold in 20' sections, and I picked up 2 for the ditch at the road. It just looks so wide!

vtsnowedin · Apr 28, 2015

As stated you need the extra length for the side slopes from the traveled way down to the top of the pipe. If you have a foot and a half of cover and 3 to 1 side slopes that will use up 4.5 feet on each end.
You can set the pipe three or four inches below the grade at the bottom of the ditch to get a little more cover. If you don't get enough cover it will pump it's way up in the spring when the frost is coming out of the ground. One foot of cover is a bare minimum and two feet is much better.

boatpilot1 · Apr 28, 2015

I drive a semi for a farmer and the semi drivers will thank you for the wider culvert. Better to do it now than when a semi runs off of the end of the culvert and gets stuck.

showcattle · Apr 28, 2015

The deeper the fill on the culvert, the longer it needs to be because of the slope of the sides of the fill.

bigtiller · Apr 28, 2015

I have a 40' one under my driveway and a 60' one under the field entrance about 500' away. Both ditches are about 3' deep, and it all looks like someone gave it some thought and made it look like the natural thing to do.

s219 · Apr 28, 2015

I started with a 20' pipe for my culvert, with a 12' driveway, and used that all through construction of our home. Later when we were finishing up the driveway, I added an additional 5.5' to each end (scraps from a narrower culvert I made) to make it 31' total, and that gave me more room to have the proper radius as the driveway flares wider to meet the street.

I think my ditch centerline is about 8' from the street, so the flare radius passes over the culvert pipe and the driveway is more like 24-25' wide right in that spot (it's about 36' wide right at the street). Now I have about 3' of shoulder on each side of the gravel driveway where it crosses over the pipe, and that's enough to put down some rip-rap stone to keep things stable. If you have a deeper crossing, you'll want a wider shoulder yet. I think my ditch was only about 2-3' deep. If I needed 31' of pipe for a 2-3' ditch, I can easily see 40' for a deeper ditch.

Don't know about your location, but here I had to follow Virginia DOT specs for the culvert, including bedding, depth, fill type, drive width, and radius/flare at the street. They pretty much set the specs and it's not up to me to decide. In this case, the street is still in the process of being turned over from the private developer to the county/VDOT, so everything has to pass inspection (the developer has failed twice, for stuff as simple as tire ruts on the shoulder from someone who did a U-turn).

tractorshopper · Apr 28, 2015

I thought 20' was a lot when I put in my first pipe at my property. I also have 20' at my house, and frankly it just wasn't enough to get my trailer in and out of easily, especially since our road is more of a lane and it's pretty narrow, which makes for a tight last minute adjustment backing out of my driveway. I added 8' at the house and now I can get the trailer in and out easier and all around just works better for us and the FedEx/UPS drivers, etc. I want to add another 20' to my property now and going forward, would never just go with 20' again.

Coyote machine · Apr 28, 2015

52' across my 'dirt' drive apron, 2x 20's and 1x 12'. Metal, 12" diameter, wrong size, actually needs to be 18" diameter. Was installed prior to me living here. Access is onto town's dirt road, and the drive has enough width for proper grading at both ends of the culvert, and lawnscape up one side of drive, ditch on lower side to run water to feed end of culvert.

40' will do must drives nicely. 20' is too short for adequate grading, slope at ends, etc. This is a job where bigger is better, and done once, then breath easy.:thumbsup:

joeu235 · Apr 28, 2015

I have a 30ft at the entrance to the property and I can easily turn a 25 ft trailer onto the road.

franklin2 · Apr 28, 2015

Don't know about your location, but here I had to follow Virginia DOT specs for the culvert, including bedding, depth, fill type, drive width, and radius/flare at the street. They pretty much set the specs and it's not up to me to decide. In this case, the street is still in the process of being turned over from the private developer to the county/VDOT, so everything has to pass inspection (the developer has failed twice, for stuff as simple as tire ruts on the shoulder from someone who did a U-turn).

Yep, I live in Va too. When I put a culvert in the first thing I had to do was get approval for were I wanted it to come out on the main road. After they approved that they told me how wide it should be and what size pipe to buy.

Fossil Farm · Apr 28, 2015

If there is a structure on the property, the fire department likes to have at least a 30 foot culvert so they can get their tankers and engines in safely. Ours is 40 foot. No sense cutting a 20 foot section in half. Might as well use it. Most should last decades.

Will_C · Apr 28, 2015

It's one of those things that for a little additional cost up front, you'll never regret.

Will

HarryN · Apr 28, 2015

YES..... you want 40 feet!

heppeone · May 10, 2015

40' at least for sure, 60' even better. Plus, if your planning on adding a gate, think about putting gate far enough back onto property to allow truck with trailer enough room to pull into driveway without end of trailer sticking out in the road while gate gets unlocked and opened.

Gary Fowler · May 10, 2015

I put in a 12" (minimum size per county) 30 foot culvert prior to building my house and it worked ok even for semi trailers but the ditch was only barely deep enough on the upstream side to get cover. My neighbor upstream has no ditch and neither does the one across the road. They said since we are at the top of the hill, they didn't need one and just filled in the ditch. I just asked to county for permission and they came out, looked and said OK but don't blame us if your yard floods. Well I got dirt trucked in and filled in the ditch, left the culvert buried under the fill. No problems in 5 years of heavy rains.

For most any driveway though 30-40 foot would be my minimum length if the ditch were more than 18" deep.

rjkobbeman · May 12, 2015

The comments about extra length to account for slopes on the side are extremely important. For example: if you have 3 feet sides (3 feet on each side), and you have 3 feet of cover on top of the culverts, the slope will be 45 degrees... which is very steep. At that slope, you will lose cover (gravel). Longer is better.

Figure out how wide you want the lane/drive. Then figure out how much cover on top of the culverts. Then figure out how much slope you want on the sides. From that, you can calculate how much extra you NEED on each side/end.

Too short of culverts become an endless pain in the rear, which in a lot of cases are not easily fixed.