[jedberg]

> If you drive to work on a toll road and then drive back home along the same toll road, you still have to pay the tolls even though you wound up in the same place at the end.

Funny you should use that example. On toll roads you get charged in both directions, but I've never seen a toll bridge that had tolls in both directions. Usually the argument is that you really can't go any other way so the toll in one direction covers the cost of both trips.

But I actually think you're right here -- most people won't make the "return trip" so it makes sense to only charge people twice that do.

[munch117]

I've never seen a toll bridge that doesn't have tolls in both directions. I didn't even know that charging in only one direction was a thing. You live and you learn.

[jedberg]

As I am also learning today. If you don't mind sharing, where do you live?

Here in the Bay Area all of our bridges only have tolls in one direction.

[shagie]

Fairly standard around Chicago area. Results for Illinois Tollway Plaza will show them (not all of them are - they can get interesting at intersections and off-ramps).

(late edit)

This is largely driven by the question "is a vehicle heading in one direction likely to return in the other?"

For trips from Oakland to SF, yes - it is very likely that the vehicle will go back across the bay bridge back to Oakland (rather than heading down to San Jose and then back up the other side).

On the other hand, a vehicle driving on the tollway through Chicago may be heading up to Minneapolis or to Detroit and then to other directions. Trips on the Illinois tollways are less likely to have a return trip and so both directions need to be tolled to capture the vehicles. It costs twice as much to do this (twice as many toll booths and staff) and so given the choice (trips to an island or other geographically isolated area) they only pay tolls in one direction.

[jefftk]

Also tolls crossing into NYC. Since going around is impractical, it means you need half as much tolling. And since the land for tollbooths would be more expensive on the NYC side your savings are even larger.

[munch117]

Denmark. We have exactly one and a half toll bridges in the whole country, so I guess the both-directionalism may be down to toll-both amateurism.

[trebecks]

some nyc bridges and tunnels charge both ways. for the bridges and tunnels connecting ny and nj, you only need to pay going nj -> ny.

[xp84]

Interesting! It may be a geographical thing. Clearly they don't want you to be able to do a free "circular commute" so for instance, in the Bay Area, all bridges charge toward San Francisco, and are free in the opposite direction. So there's no way to do a circular commute that wouldn't add 100+ miles by circumnavigating the Bay every day. But it seems like it "should" be simple enough (Dangerous words!) to coordinate say, "all bridges over a river in the metro area charge eastbound."

It seems kind of a waste from my perspective to have to do the traffic bottleneck in two directions.

[dymk]

An example: to use the ferry system here in Washington’s Puget Sound, you pay to go to the island, but the return trip is free. Same applies for bridges taking you to islands.

[__derek__]

> I've never seen a toll bridge that had tolls in both directions.

Huh, I think I've only seen this once (the Tacoma Narrows Bridge). Other toll bridges I've driven have all had tolls in each direction, e.g., Ambassador and Blue Water Bridges to Canada, Lake Washington floating bridge. Maybe I need to start taking more bridges to nowhere!

[dymk]

The floating bridge has a toll in both directions because there’s an alternate route which isn’t too much worse when there’s no traffic (and something about federal highway grant money)

[jedberg]

Interesting! I'll admit my sample size is limited to bridges in California, but at least in the Bay Area all the bridges only have tolls in one direction.

[dragonwriter]

I suspect the Bay Area model is more common where the dominant traffic on a bridge is two-way commute traffic that can’t easily escape the toll regime for one side of the commute. In that case, one-way tolls reduce infrastructure and operating costs, and traffic impacts, of toll collection without any significant downside.

[duskwuff]

The other half of that is a practical matter -- collecting tolls in both directions means constructing and staffing a larger and more complex toll plaza. It's hard to justify that expense unless a lot of tolls will go uncollected without it.

[dragonwriter]

> The other half of that is a practical matter -- collecting tolls in both directions means constructing and staffing a larger and more complex toll plaza

That’s part of what I waa getting at with “infrastructure cost”, yes.

[__derek__]

That makes sense. It fits with the Tacoma Narrows Bridge, which connects Tacoma (urban economic hub) to the Olympic Peninsula (some small towns, mostly wilderness).