S&P/ASX 200 Index (ASX: XJO) dividend stock Transurban Group (ASX: TCL) is marching higher today.

Shares in the ASX listed toll road developer and operator closed yesterday trading for $13.89. At time of writing in afternoon trade on Thursday, shares are changing hands for $13.94 apiece, up 0.4%.

With Transurban having paid out 64 cents a share in unfranked dividends over the past year, that sees the ASX 200 dividend stock trading on a trailing yield of 4.6%.

And the future dividend outlook looks to have gotten a boost following the release of Transurban's March quarterly update.

Here's what we learned.

ASX 200 dividend stock reports increasing demand

The ASX 200 dividend stock is in the green after its March quarter 2025 traffic update revealed that Average Daily Traffic (ADT) across its road networks averaged 2.5 million trips a day, up 1.8%.

The growth was driven by increased traffic in all of Transurban's operational regions, except Queensland.

ADT on its Brisbane roads dipped 0.4% over the quarter. Management noted that traffic was impacted by Ex-Tropical Cyclone Alfred. Excluding the impacts of the cyclone, they said underlying ADT across the Brisbane portfolio grew 4.5% over the three months.

And heavy vehicle usage across the Brisbane assets increased 4.4% for the quarter supported by 4.5% growth on Gateway and Logan.

In Sydney, ADT grew by 2.4%. According to the release, this was predominantly driven by 10.3% growth on its WestConnex toll road and 2.8% on NorthConnex. The company noted that, "Heavy vehicles remain resilient across the Sydney portfolio, up 0.4%."

The ASX 200 dividend stock also saw ADT on its Melbourne roads grow by 2.0%. Management said this was driven by strong discretionary travel, with weekend growth of 3.3% outperforming weekday growth of 1.3%. Airport-related travel also improved, while construction impacts across Melbourne were lower.

Melbourne's 2.1% heavy vehicle growth was supported by a 5% increase in Port of Melbourne container volumes.

On the international front

Transurban also reported that even the headwinds from heavy winter conditions and construction closures on the 495 Express Lanes at its North American operations didn't derail quarterly traffic growth in the United States.

The company said that traffic in North America grew across all its assets, driven by 6.6% growth on the 495 and 3.9% growth on the 95 Express Lanes. And the A25 traffic increased 1.5%, despite the LaFontaine tunnel-bridge repairs continuing to dampen full recovery.

Transurban said it is continuing to "monitor the changing work from home landscape and policy shifts in the US" which could impact future traffic flows.

With today's gains factored in, shares in the ASX 200 dividend stock are up 8% since this time last year. Not including those dividend payouts!