There are many articles and websites referring to the highest point of a curved bridge as the "crest" of the bridge.

One example, which clearly describes an ascent before the rider reaches the crest and then descends:

https://discoversouthcarolina.com/articles/bike-across-the-r...

From the walkway leading up to the Mount Pleasant side of the span, the bridge doesn't seem all that steep. Wrong! I had barely entered the 12-foot wide pedestrian and bicycle lane before I was rapidly downshifting. But you pay a price for pedaling the gears of least resistance. The uphill trek seemed to take forever.

When you've had just about enough of the ascent, you're finally there-the crest of the bridge. The view from the top gives you a great excuse to stop and catch your breath.

If you linger long enough, you're bound to catch a freighter or container ship passing underneath the bridge, giving you a bird's eye view of its topside.

But it's the rollercoaster ride down the bridge that gets my heart racing. I can't tell you the top speed you'd hit if you didn't use your brakes because I've never managed to do it. At about 25 miles an hour, I sprout chicken feathers.

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Note added at 4 hrs (2022-11-06 11:20:52 GMT)
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I also see the word "apex" being used in several books and articles. This is another good option.