He is traveling and joining the prayers is easier for him

Firstly: 

It is permissible to join Zuhr and ‘Asr prayers, and Maghrib
and ‘Isha’, for one who is traveling. That is indicated by many ahaadeeth,
such as the following: 

1 – al-Bukhaari (1108) narrated that Anas ibn Maalik (may
Allaah be pleased with him) said: The Prophet (peace and blessings of
Allaah be upon him) joined Maghrib and ‘Isha’ prayers when traveling. 

2 – Ahmad (3178) narrated from Ibn ‘Abbaas that the Messenger
of Allaah (peace and blessings of Allaah be upon him) joined two
prayers whilst traveling. Shaykh Ahmad Shaakir (3288) said: Its isnaad is
saheeh. 

3 – In Saheeh Muslim (706) it was narrated that
Mu’aadh said: We went out with the Messenger of Allaah (peace and
blessings of Allaah be upon him) on the campaign of Tabook, and he used to
pray Zuhr and ‘Asr together, and Maghrib and ‘Isha’ together. 

A traveler may be of two types: 

1 – When he is actually on the road

2 – When he has made a stop, i.e., he is not on the road;
either he has reached the place to which he is traveling, or he has made a
stop on his journey and stayed there for a while. 

It is permissible for any traveler to join prayers, whether
he has made a stop or is on the road. 

But is it better for the traveler to join the prayers or to
offer each prayer at its proper time? 

Shaykh Ibn ‘Uthaymeen said in his essay on the times of the
prayer (Mawaaqeet al-Salaah, p. 26): 

It is better for the traveler who has made a stop not to join
the prayers, but if he joins them there is nothing wrong with that, unless
he needs to join them because he is tired and needs to rest, or because it
is hard for him to find water each time, and so on, in which case it is
better for him to join the prayers and avail himself of the concession. But
for the traveler who is on the road, it is better for him to join Zuhr and
‘Asr, and Maghrib and ‘Isha’ – in the way that is easier for him, either
praying them at the time of the earlier prayer or the time of the later
prayer. 

Based on this, it is better for you to avail yourself of the
concession, and join Zuhr and ‘Asr at the time of Zuhr, because this is
easier for you. The Messenger of Allaah (S) was never given the choice
between two things but he would choose that which was easier, so long as it
was not a sin, in which case he would be the most careful of people to avoid
it. Narrated by Muslim, 3560; Muslim, 2327. 

In this case you have to strive to pray ‘Asr in congregation
and look for someone to pray with you. 

Secondly: 

With regard to praying
‘Asr in the train whilst sitting, this is permissible according to the
majority of scholars, if you cannot pray standing. 

It says in Fataawa al-Lajnah al-Daa’imah (8/120): 

If the time for prayer comes and the plane is still in the
air and there is the fear that the time for prayer will end before it lands,
then the scholars are agreed that the prayer must be offered in whatever
manner one can, bowing, prostrating and facing the qiblah if possible,
because Allaah says (interpretation of the meaning): 

“So keep your duty to Allaah and fear Him as much as you
can”

[al-Taghaabun 64:16] 

And the Prophet
(peace and blessings of Allaah be upon him) said: “If I tell you to do
something, do as much of it as you can.” Agreed upon. 

But if it is known that the plane will land before the time
for prayer ends, and there will be enough time to offer the prayer or the
prayer is one which can be joined with another – such as Zuhr which may be
joined with ‘Asr, or Maghrib which may be joined with ‘Isha’ – and it is
known that the plane will land before the time for the second prayer ends
and there will be enough time to offer the prayers, then the majority of
scholars are of the view that it is permissible to offer the prayers in the
plane, because it is obligatory to offer them when the time for prayer
begins, in whatever manner one can, as stated above. This is the correct
view. 

And it also says (8/126): 

It is not permissible to pray sitting down in a plane or
elsewhere if one is able to stand, because of the general meaning of the
verse (interpretation of the meaning): 

“And stand before Allaah with obedience”

[al-Baqarah 2:238] 

And the hadeeth of ‘Imraan ibn Husayn which was narrated by
al-Bukhaari: that the Prophet (peace and blessings of Allaah be upon
him) said to him: “Pray standing, and if you cannot, then sitting, and if
you cannot, then on your side.” Al-Nasaa’i added, with a saheeh isnaad: “And
if you cannot, then lying on your back.” 

Some of the scholars are of the view that it is not
permissible to pray in planes, trains or cars because it is not possible to
offer the prayer as it is offered when standing on the ground – unless there
is the fear that the time for the prayer will end. 

Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) said in
Fataawa Arkaan al-Islam (p. 380): 

It is obligatory to pray in a plane if one does not know the
time of the prayer, but if he cannot offer the prayer in the plane as he
offers it on the ground, then he should not offer obligatory prayers in the
plane if the plane will land before the time for prayer is over, or the time
for the following prayer if it is a prayer that may be joined with another.
For example, if a plane takes off from Jeddah just before sunset and the sun
sets whilst it is in the air, he should not pray Maghrib until the plane
lands and he disembarks. But if he fears that the time will end and he
intends to join it to ‘Isha’ at the time of the latter, he can pray them
when he lands. But if the plane keeps on flying and there is the fear that
the time for ‘Isha’ will end, which is at midnight, then he should pray them
in the plane before the time ends. 

Based on this, in order to be on the safe side, you should
not pray ‘Asr in the train, rather you should join it with Zuhr at the time
of Zuhr, as stated above.