Well it seemed to be higher in case of US atleast.
Sylvain Leduc and Daniel Wilson summarise their recent work on impact of highway program under ARRA (American Recovery and Reinvestment Act). The states which implemented ARRA fundinding for highways showed multiplier of 2!.
One criticism of public infrastructure programs is that they take a long time to put in place and therefore are unlikely to be effective quickly enough to alleviate economic downturns. The fact is, though, that surprisingly little empirical information is available about the effect of public infrastructure investment on economic activity over the short and medium term.
This Economic Letter examines new research (Leduc and Wilson, forthcoming) on the dynamic effects of public investment in roads and highways on gross state product (GSP), the total economic output of a state. This research focuses on investment in roads and highways in part because it is the largest component of public infrastructure in the United States. Moreover, the procedures by which federal highway grants are distributed to states help us identify more precisely how transportation spending affects economic activity.
We find that unanticipated increases in highway spending have positive but temporary effects on GSP, both in the short and medium run. The short-run effect is consistent with a traditional Keynesian channel in which output increases because of a rise in aggregate demand, combined with slow-to-adjust prices. In contrast, the positive response of GSP over the medium run is in line with a supply-side effect due to an increase in the economy’s productive capacity.
We also assess how much bang each additional buck of highway spending creates by calculating the multiplier, that is, the magnitude of the effect of each dollar of infrastructure spending on economic activity. We find that the multiplier is at least two. In other words, for each dollar of federal highway grants received by a state, that state’s GSP rises by at least two dollars.
As Lin said roads that lead to somewhere and some positive impact.