Quebec Autoroute 31  Autoroute 31 (A-31) is an Autoroute in the region of Lanaudière in Quebec. Constructed in 1966, the A-31 primarily links Joliette with the A-40 and in turn to Montreal, Trois-Rivières, and other points served by Quebec's autoroute system. The A-31 is only long, making it one of the shortest autoroutes in the province. It is multiplexed with Route 131 for its entire length. The A-31 also carries the name Autoroute Antonio-Barrette, named for a politician from Joliette who briefly served as Premier of Quebec in 1960. The A-31 begins just south of its interchange with A-40 in Lavaltrie. Motorists exiting the A-40 can opt to travel north on A-31 (multiplexed with Route 131) or south on Route 131 to Lavaltrie's city centre. The A-31/A-40 interchange has an unusual configuration, built to accommodate tollbooths (since dismantled). Also unusual for a Quebec autoroute: agricultural vehicles like tractors are permitted to cross over the A-40 by travelling on A-31 from its southern terminus to exit 2. For this reason, an automated traffic regulation system (commissioned in 2009) lowers the speed limit automatically from 100/60 km/h to 90/30 km/h as needed. Exits at km 2 and km 7 provide access to local roads, while a partial interchange at km 12 serves an industrial zone south of Joliette. The A-31 ends at km 15 at a cloverleaf interchange with Route 158. Plans for Quebec's autoroute system initially called for A-31 to meet the A-50 at this interchange. Anticipating this outcome, Route 158 in the immediate vicinity of the interchange was constructed as a limited-access highway and signed as A-50. Once plans to extend the A-50 east of the A-15 were abandoned in the 1980s, this stretch of highway was redesignated Route 158. A series of deadly accidents on Route 158 prompted a 2014 petition drive to reconstruct the highway to Autoroute standards and return the designation of A-50. Motorists exiting the A-31 at km 15 may continue on Route 158 west to St-Esprit, Route 158 east to Berthierville, or Route 131 north to Saint-Félix-de-Valois.