Maine, school buses may not exceed on roads with higher speed limits while transporting students. At other times, the limit is , unless on an Interstate highway, in which case the posted limit applies. Fines for speeding are at least $50 by law. Exceeding the speed limit by or more is considered a criminal offense. Maryland The speed limit on Maryland's Interstate Highways are posted by default at 65 mph although 70 mph limits can be posted after a traffic and engineering study. Effective October 1, 2015, the speed limit on I-68 is 70 mph except for a seven-mile section around Cumberland. Effective April 4, 2016, the speed limit on I-70 has been increased to 70 mph from the Pennsylvania state line to MD 180 in Frederick County and from MD 144 in Frederick County to US 29 in Howard County. Maryland's urban freeways normally have speed limits of 55 mph (like I-495) or 60 mph, although some stretches are signed for 65 mph travel such as portions of I-95 and I-97 in and around the Baltimore suburbs, I-70 around Frederick, and I-81 around Hagerstown. I-70 around Hagerstown is posted at 70 mph. More restrictive limits are found on I-83 south of North Avenue when approaching downtown Baltimore and on I-68 through Cumberland, both sections being marked at 40 mph. Four lane non-interstates and non-freeways are posted at 55 mph. This includes the expressway grade roadways like US 50 and US 301 east of the Bay Bridge, US 15 north of Frederick to the Pennsylvania state line, MD 404 around Denton and US 29 between I-495 and I-70. US 340 from Brunswick to I-70 in Frederick however is posted as 65 mph. Normally, speed limit drops are in 5 mph to 10 mph increments. However, one speed zone drops from 55 to 25 mph along US 301 southbound at the Nice Bridge for the toll plaza. Two lane roads are generally posted at 50 mph but there are a handful of routes posted at 55 mph. It is more common to see 55 mph on the Eastern Shore and in Frederick and Carroll counties than the Baltimore-Washington corridor and Western Maryland. Two lane routes that have a speed limit of 55 mph enforce mandatory headlight use. Urban and downtown speed limits are generally posted at 30 mph. Massachusetts As prescribed by Massachusetts law, default speed limits are the following: in