Maybank Kim Eng Thailand has these great updates on a weekly basis regarding the Infrastructure Investment, see below for a succinct summary.

Who benefits from this? Well the usual players, CK, STEC, UNIQ, ITD, maybe the smaller ones too hopefully, i.e. NWR, CNT, PYLON, etc…
Investment: Infra investments update
The Cabinet approved construction of a Yellow Line and a Pink Line. The government will now look at the bidding process to ensure it takes place within the next three months. The rail links are needed to reduce traffic congestion in Bangkok, which currently has three skytrain lines and one underground line.

Mass-transit routes in Greater Bangkok: Yellow Line (Lat Phrao-Samrong (a straddle-type monorail line)) (THB52b) (2016-2019 or earlier)
Funding: Some included in FY16 budget. The government will invest no more than THB20b, covering the land expropriation costs and many of the civil works. The private sector will invest in the remaining civil engineering projects, trains, operating systems, and maintenance services, under a 30-year concession.

Current status: Fast-tracking PPP project; feasibility study finished; EIA finished; approved by the PPP committee 29 Feb 2016; approved by the Cabinet 29 Mar 2016; international bidding and private participation selection by May 2016; construction to start in Jun 2016.

PPPs: Yes; construction and operation. The government will invest no more than THB20b, covering the land expropriation costs (THB6.01b) and many of the civil works; the private sector will invest in the remaining civil engineering projects, trains, operating systems, and maintenance services, under a 30-year concession; the private sector must take all risks – under the PPP Net Cost model – if the number of passengers is not as expected.

Distance: 30.4km. The daily ridership for is estimated at 247,900 person.

Mass-transit routes in Greater Bangkok: Pink Line (Khae Rai-Min Buri (a straddle-type monorail line)) (THB54b) (2016-2019 or earlier)
Funding: Some included in FY16 budget. The government will invest no more than THB20b, covering the land expropriation costs and many of the civil works. The private sector will invest in the remaining civil engineering projects, trains, operating systems, and maintenance services, under a 30-year concession.

Current status: Fast-tracking PPP project; feasibility study finished; EIA finished; approved by the PPP committee 29 Feb 2016; approved by the Cabinet 29 Mar 2016; international bidding and private participation selection by May 2016; construction to start in Jun 2016.

PPPs: Yes; construction and operation. The government will invest no more than THB20b, covering the land expropriation costs (THB6.85b) and many of the civil works; the private sector will invest in the remaining civil engineering projects, trains, operating systems, and maintenance services, under a 30-year concession; the private sector must take all risks – under the PPP Net Cost model – if the number of passengers is not as expected.

Distance: 34.5km. The daily ridership for is estimated at 270,000 persons.
Source: Local press, The Nation, Bangkok Post, Reuters, Bloomberg, MBKE