Each bridge has to be identified and related questions have to be answered, in total 8 missions to be completed; one of them is only a "bridget"(newly created word for a small bridge). This geocache has nothing to do with "Ponts et Chaussées", the Luxembourg civil servant department (Administration des Pont et Chaussées) in charge of the motorways (including tunnels and street lighting equipment). Any identified similarities would be of pure coincidence.
A1= How many railroad tracks (voies ferrées du réseau tertiaire CFL-Cargo) can be seen below this bridge
A2= 1st digit of the name of village (quarter) where this passerelle is located

B1= max height above ground of x meters of this viaduct
B2= Number of letters in the name of this bridge (without viaduct)

C1= Total length of x meters of this bridge inaugurated on June 2nd, YYYY
C2= Checksum of the year (only the 2 last digits: ..YY) when the bridge was inaugurated

D1= Total length of x meters of the blue bridge
D2= 2nd letter of the bridge construction type as called/known in the UK and most Commonwealth countries

E1= Time expressed in years it took to build this "new" bridge
E2= 3rd letter of the river below the bridge

F1= Checksum of the year when the bridge was inaugurated
F2= 3rd letter of the city on the left bank of the river below this bridge

G1= Checksum of the total length of the bridge expressed in meters
G2= Time expressed in years it took to build this bridge

H1= Number of letters in the national language of the name of the "river" (creek) flowing below this "bridget"
H2= 1st letter of the village nearby the source of this "river" (creek)

Now go for the Ponts sans chaussées Cache at:
N 49 "3" "(D2-B2)" . "((B1+G2)/(H1*H2)-E2)" "(A1-B2)" "(C1-D1)/(E1-A2)"
E 006 "0" "(G2-F1)" . "(G1)" "(D1/F2)-(E2-B2)" "(G2-C2)"

Official Stats GC5PBJQ:
FTF ex aequo by Garfield1970 , Koouye & speedwalkers