There are no roads  to MP. You can get there by train, walking (Inca Trail) or by an alternative route through Santa Teresa (which involves walking or train). For the Inca Trail, please refer to the existing article on Trip Advisor.

There are three train companies: Peru Rail, Inca Rail and MachuPicchu Train. For Peru Rail and Inca Rail, trains depart from Poroy station (a 20-minute trip from Cusco) or from Ollantaytambo station, located in the Sacred Valley.

The trains arrive at Machu Picchu Pueblo (also known as Aguas Calientes). From the main train station, it is a short walk to the Consettur bus stop. Bus tickets can be purchased online or at the bus stop (cash USD or PEN).  Here is a map of the walk from the main train station to the bus stop.

Peru Rail 

Three type of services are offered, the Hiram Bingham , the Vistadome and the Expedition (previously known as Backpacker). A local train also does the route but you must have a Peruvian ID to be able to use it. The ride from Cusco takes about 4:15 hours and from Ollantaytambo about 1:15 hours. For schedules and ticket prices go to the  Peru Rail website.

Inca Rail 

They offer two types of services: executive (panoramic views + snacks), and first class (more comfortable + reading books). For ticket prices and schedules, go to the Inca Rail website. They depart from Ollantaytambo.

* You can get  to Ollantaytambo by taxi (1:30 hours, $40), minivans (1:30 hours, S/.10 per person)  or  by bus (2:30 hours, $2).

It is recommended to secure your train tickets before you make your plans to visit MP, then you can book the rest of your trip schedule. During the high tourist season  from June to August you have to be specially careful. You can use their website to purchase the tickets or you can also buy them at the Peru Rail stand in Larcomar (a shopping center in Miraflores) or the airport (both companies). There are also offices in Cusco.

It might prove quite difficult to make reservations for your train tickets. What happens is that travel agencies and hotels and others can block a number of seats on the train in advance. Only 11 days before the departure date, the tickets have to be reconfirmed with names, passport numbers and paid. At this time, is when tickets become available again on a first come first serve basis.

Another way is to ask your hotel to get tickets. You need to provide your passport number. Tickets are issued in your name and are none transferable nor refundable. Some hotels  provide this service for a fee.You can also check with hotels in the Sacred Valley, as they are smaller hotels, they normally provide these extra services at low commissions. Travel agencies can also provide tickets, with a surcharge or commission.

Do not risk going to Cusco with the idea of getting tickets a couple of days before going to MP as you could be very disappointed and miss your opportunity  to visit MP altogether. 

Santa María-Santa Teresa-"Hidroeléctrica" - WARNING, dangerous unpaved mountain road!

Arrive to Santa Teresa and then a short taxi-ride further is Hidroelectrica where you can take a train to Aguas Calientes or take a 2 and a half hour walk there. Cusco to Santa María is a 4-hour journey by minivan and costs about 30 soles, or you can take a bus (15 soles) for a 5-hour drive. The dirt road is narrow and winding, surrounded by deep hills. The town is small and a mere shadow of its former glory before the floods of 1998 when over 80km of railway line was washed away between Aguas Calientes and Quillabamba (a huge coffee-producing town). You can take a walk to Santa Teresa along the river (June-November) or take public transport from the main road (1 h 30 minutes). Santa Teresa was another old colonial town which has been reconstructed after the 1998 floods. From here to Hidroeléctrica is a 25-minute journey by minivan or taxi (approximately 6 soles). Hidroeléctrica is literally the end of the line for the railway, you can either walk or take a train ride to the town of Aguas Calientes. This route allows travelers on a tight budget to reach Machu Picchu but it might be dangerous during the rainy season (high risk of landslides, avalanches).

Many tour operators in Cusco offer "Macchu Picchu by car, 2days 1 night" trips for half the price of their train tours (around $95 by "car"), They may  mention that the road is "bad" after Santa Maria, it is in fact very bad even in dry weather and one mini-van (Feb 2016) broke down on a mountain road, the driver had to leave passengers all roadside while he hitched a lift back to where there was mobile phone signal. DRIVERS GO QUITE FAST AND OVERTAKE EACHOTHER VERY CLOSE TO SHEER DROPS sometimes even when there is also a pedestrian or bike. Tour also arrived at Hidroelectrica late (this did not seem to be unusual) meaning that the 5km hike along the train tracks (no guide) from Hidroelectrica to Aguas Caliente was in the pitch dark and included walking over rickety rail bridges over the fast flowing river and sometimes stepping from sleeper to sleeper over steep drops. NOT FOR THE FAINT HEARTED. The train ride to Aguas Caliente is more expensive but is safe and comfortable along the riverside. Feb 2016 the train only ran from Ollantaytambo (not Poroy) but the minibus to Ollantaytambo from Cusco is on a paved road and only 10 Soles. Best to take a minibus from Cusco to Ollantaytambo then the train from Ollantaytambo to Aguas Caliente and back.