No bridge? Try a tractor.

Are the roads as bad as they say?

In a word, yes

Costa Rica has about 23,000 miles (37,000 km) of roads; fewer than 5000 (8,000 km) of them are paved. And paved is sometimes worse than unpaved–a gravel road can be well-graded and in excellent repair, while a "paved" road may be riddled with deep holes. The U.S. State Department rates roads here, and the availability of roadside assistance, as "fair to poor." I guess that’s better than "poor to abysmal," but still, you need to make some adjustments when you’re driving in this country.

Slow down

You must be ready for anything–trucks passing on a hill, potholes big enough to do your vehicle real damage, and cops hiding behind the next palm tree. Police here have radar guns and they love to use them. Speeding tickets can be very expensive–up to $150 if you’re really making time. Pay attention to speed limit signs, even if it seems that there’s no one else on the road. Speed traps are common on the most-traveled routes to tourist areas.

As elsewhere in the world, Costa Rican drivers signal trouble up ahead by flashing their lights at oncoming cars. Of course this can also mean, "Turn off your brights!," but if someone flashes you, slow down and be on the lookout either for an accident, a damaged roadway, or a police car. If you’re behind someone and they flash their lights, it can mean "The road is clear for you to pass," but be aware that what Costa Rican drivers consider a safe distance to pass is a fraction of what most North American drivers deem necessary.

Wear your seat belt–it’s the law. A selectively enforced law, but a law nonetheless.

If you have an accident

Even as you try to drive by the book, other drivers will be throwing that same book out the window–turning across two lanes of traffic without signaling, hoisting a bottle while passing on a blind curve, or realizing that yes, they really should have had the brakes fixed last week. If the worst happens and you have an accident, stay in your car until the police arrive. If you’re out in the middle of nowhere or in the middle of a highway, this will be impractical, of course. But if it’s possible to wait, do so, so as not to open yourself up to liability issues.

Traffic enforcement in Costa Rica is the responsibility of the Transit Police (Transitos), who wear light blue shirts and dark blue pants, and drive light blue cars or motorcycles equipped with blue lights. (Regular police drive dark blue cars.) Transit cops often wave vehicles to the side of the road for inspection, asking drivers for their driver's license, vehicle registration and insurance information. Fines are not supposed to be collected on the spot, although reports of officers attempting to collect money are common.

Accidents may be reported by dialing 911.

Most accidents occur at night–do what you can to not drive after dark. Most roads are unmarked and unlit. Fog and torrential rains can make the way even rougher.