How Long Does It Take to Plan a Bridge? - by Brian Potter

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How Long Does It Take to Plan a Bridge?<br>Brian Potter<br>Jun 04, 2026

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Bear Mountain Bridge in New York, via Wikipedia.<br>Many folks, including me, have observed that it seems to take much longer to build infrastructure in the US than it used to. People point to things like the rapid construction of the Empire State Building (one year) or the Golden Gate Bridge (just over four years) and note that for a modern infrastructure project it can take that long or longer to even get the permits or do the environmental studies.

Via Threads. Note that as of 2026 permit timelines for San Francisco housing have gotten much better.<br>But when doing these sorts of comparisons, it’s important to compare like with like: specifically, we shouldn’t measure the time spent planning a project (which would include doing the environmental studies and securing the permits) against the time spent actually building it. (The Golden Gate Bridge, for instance, was constructed in four years from 1933 to 1937, but planning for the project began around 1921.)<br>I wanted to get a sense of how planning times for major infrastructure projects in the US have evolved over time. To do this, I looked at planning and construction times for 67 major bridges built in the US since roughly the beginning of the 20th century. For each bridge, I noted the year that planning began, the year that construction began, and the year that it opened for service.1<br>As usual with an exercise like this, the results you get will be a function of the definitions you choose. “Started construction” and “opened for service” are relatively unambiguous — but what specifically do we mean by “planning begins”? People will often float the idea of a bridge for years before anything resembling formal plans is in place; the idea for the Brooklyn Bridge, completed in 1883, apparently dates back to 1804, but it doesn’t seem reasonable to consider that early discussion the beginning of planning. On the other hand, if you choose something like “the government formally announces the project” as your criterion, that might exclude years of serious efforts to get a project constructed.<br>I ended up choosing the “planning begins” date as the point when some organization connected with transit planning in some official capacity first announced or proposed the project. So for the Golden Gate Bridge, this would be 1921, when Chicago engineer Joseph Strauss and San Francisco city engineer Michael O’Shaughnessy prepared a joint proposal for the bridge. However, pinning these dates down was often difficult. Most bridges aren’t the Golden Gate Bridge, with lots of publicly available sources chronicling their design and construction. Often sources give a brief “planning begins” date without explaining what that meant specifically or what activities preceded it. And for some bridges, such as the New Tappan Zee Bridge, the decision to proceed with a bridge was preceded by years of studies on possible ways to expand transit capacity that considered many non-bridge options. For these, I tried to use the initiation of broader studies as the start of planning, but I suspect that these sorts of preliminary studies weren’t always documented. Overall I did my best to determine the dates, but I expect there to be errors and inconsistencies, and the results below should be taken with a grain of salt.<br>Those caveats out of the way, let’s look at the data. The graph below shows planning times for each bridge on the list. The horizontal axis is the year when planning began for a particular bridge, and the vertical axis is total years of planning.

And the graph below shows construction times for each bridge.

Because there’s a lot of variation in both planning times and construction times, it’s useful to look at trends by age bracket. The chart below shows average planning times and construction times for 20-year age buckets, with pre-1900 and post-2000 bridges each given their own bucket.

There are a few trends visible here. One is that bridge construction times fell from 1900 to the 1960s, but since then have risen. The average time to construct a bridge between 1980 and 1999 (6.5 years) was more than twice as long as the average construction time for bridges built between 1940 and 1959 (3.1 years). Construction times for bridges built between 2000 and 2025 are down from this peak (5.4 years), but they’re still well above the times of the 1920s through the 1950s.<br>Planning timelines, on the other hand, show a somewhat different trend. At a high level, we do see something that looks like the “times fall, then rise again” pattern we saw with construction times: planning times fell in half from over 12 years between 1900 and 1919 to 6 years between 1960 and 1979, before rising again in the 1980s. But the 1980-1999 period planning times look fairly similar to every other period other than 1960-1979. It’s not clear that modern...